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Mac IIsi - Clock Chip to 25 Mhz - How to ?
- Thread starter MacOS
- Start date
Franklinstein
Well-known member
The processor on that thing is factory-rated to 20MHz, it wasn't an underclocked 25MHz chip thrown in by Apple.
Anyway, that's one of the Macs where a clock crystal would need to be replaced (like most 68k and early PPC models).
I don't have a IIsi in front of me, so I can't say exactly where it would be, but there's a 20MHz oscillator somewhere on the logic board (either a small two-lead can type or, more likely, a larger rectangular type) that will need to be replaced with a faster part. There are likely a couple of different oscillators on the board, so make sure you replace the correct one.
Anyway, that's one of the Macs where a clock crystal would need to be replaced (like most 68k and early PPC models).
I don't have a IIsi in front of me, so I can't say exactly where it would be, but there's a 20MHz oscillator somewhere on the logic board (either a small two-lead can type or, more likely, a larger rectangular type) that will need to be replaced with a faster part. There are likely a couple of different oscillators on the board, so make sure you replace the correct one.
MacOS
Well-known member
Hi,
this says http://lowendmac.com/ii/macintosh-iisi.html
Hum... where can I get that one...
this says http://lowendmac.com/ii/macintosh-iisi.html
at http://en.wikipedia.org/wiki/Macintosh_IIsi
As you say Franklinstein I need to get a faster clock crystal.
Hum... where can I get that one...
Last edited by a moderator:
MacOS
Well-known member
Nope, it is soldered to the board(bottom left, smallish square chip):
See the four silver rectangular canisters near the top, under the large black RBV chip? IIRC, the third from the left is the cpu clock, but I'd have to double check. It is 40.000 Mhz so to make the cpu run at 25 Mhz you need to replace this with a 50.000 Mhz crystal. I'd socket it so you can try different crystals.
tomlee59
Well-known member
You won't have to replace the CPU, most likely. I've never run into a IIsi that didn't "overclock" (actually, re-clock) to 25MHz. And this is a case where the speed difference is very noticeable. At 20MHz, the IIsi barely gets everything done. In imprecise terms, an extra 25% clock speed is all used to accelerate user tasks, so it will feel much zippier.
Quadrattic
New member
Is this information of any use (cut and pasted from an old text file I obtained a long time ago):
----------
Mac Crystal Oscillator Speedup History 2.5b
November 1994
------------------------------------------------------------------------
There has been a great deal of interest expressed over the net about these
simple and inexpensive Macintosh modifications that yield 20-60% speed
increases. Over the last two years I have been doing a fair amount of crystal
oscillator swapping/acceleration on Mac's, and gathering information from
others. I've made several posts to comp.sys.mac.hardware with the bulk of this
info and as new machines come out, and new concerns surface, I will try to add
them to this history of the modifications, post them on comp.sys.mac.hardware
and make them available for anonymous ftp on sumex-aim.stanford.edu and its
mirrors in /info-mac/info/hdwr. Included in this version are some more stats on
the PowerMac's and on the Apple PPC PDS card in the Centris' and Quadra's. I've
also started a Clock Chipping Home Page which has the latest history file, and
several other useful files. The URL is:
http://bambam.cchem.berkeley.edu/~schrier/mhz.html
------------------------------------------------------------------------
A little background:
All computers operate at a certain frequency with which operations are
performed. Within a certain class of computers, for example Mac's with a 68030
processor, the higher the frequency, the higher frequency of operations
processed, and the faster the computer provided there is no other speed
effecting hardware like a cache or slow data path. The designer of the computer,
Apple in this case, will use components that are rated at the same frequency or
faster than the final computer will be. In this case the 68030's are made by
Motorola. All 68030's are generally alike in what they do, but they are not
alike in how fast they can do it. Motorola sells several 68030 processors rated
at 16, 20, 25, 33, 40 and 50MHz for Mac's, accelerators and such. A large
frequency difference will require a different mask during production of the
processor, but small changes may not. Motorola only needs to guarantee that the
chip they mark as 20MHz will function properly at 20MHz under a variety of
conditions. Some chip vendors will test parts at different frequencies and sort
the chips accordingly while others may just label the them at will and sell the
chips at the different price as long as they are within the specifications.
Because of this it is reasonable that the 20 and 25's actually come from the
same batch, are separated on demand, and tested to make sure they will withstand
that frequency. And thus it is reasonable that a 20MHz processor will function
fine at a higher frequency, say 25MHz. Running the 20MHz part at 25MHz will
generate more heat than at 20MHz, but no more than the 25MHz part if they came
from the same production mask.
Many of the components in the computer need to be synchronized, so a fundamental
frequency is generated by a crystal oscillator to synchronize them. Other parts
like NuBus cards and video do not have to be the same frequency, so they may
have separate crystal oscillators. A typical computer may have three crystal
oscillators to clock different groups of components on the motherboard. Provided
the components that are clocked by a particular crystal oscillator are capable
of a speed increase, that crystal oscillator may be replaced with one of a
higher frequency. How much a specific Mac can be sped up by this method depends
on how the motherboard was designed, the components used, and what things the
crystal oscillator that controls the processor also controls. With some of the
newer Mac's, there are a few MHz differences in the top speeds reported for the
same model, so part of this is luck of the draw.
This crystal oscillator swapping has been done for years, and some early
computers even had jumpers that made it really easy to disable one oscillator
and enable another higher frequency one. The first Mac's to be modified were the
IIsi's. A stock IIsi's runs at 20MHz, and IIci's at 25MHz, and since the
architecture of these machines was so similar it seemed reasonable to run a IIsi
at IIci speeds. Another important factor was that earlier Mac's had just one
crystal oscillator that controlled everything, and if you replaced it you would
mess things up. The IIsi was different as some noted through its frequency
deviation from its 8 and 16MHz precursors where the main frequency was halved
and quartered to run the CPU, serial ports, video... The IIsi was different, it
had 4 crystal oscillators, only one of which controlled the processor speed.
The Crystal Oscillator:
The type of crystal oscillator in the early Mac's is a full size, 14 pin
package, TTL type crystal oscillator. It is a rectangular metal can, with
approximate dimensions of 2.0 x 1.3cm and typically about 0.3-0.6cm high. All
crystal oscillators have at least 4 pins. Some are numbered 1,2,3,4 and others
1,7,8,14. Pin 1 is always the pin next to the pointed edge (the others are
rounded), with the dot, or next to the indentation on the newer CMOS, or surface
mount crystal oscillators. With the pins facing down, put the dot, or
indentation to your left, and the pin on the left, closest to you is pin 1.
Going counter clockwise, pin 2 (or 7, depending on what numbering scheme) is to
the right, pin 3( 8) right side and further away, and 4(14) left side, and
further away. Pin 1 on all the newer Mac's with surface mount crystal
oscillators, and some of the older ones is an output enable/disable pin (OE). On
some of the crystal oscillators you purchase pin 1 will be OE, yet on many it
will not be used (no contact (NC)). It is not important which you get as you
will not be using the output enable feature on the new oscillator. If you ground
pin one with a jumper to pin 2(7) on an OE oscillator you disable the
oscillator. Pin 2(7) is a ground. Pin 3( 8) is the output. Pin 4(14) is the
supply voltage, +5 VDC.
I've checked a few of the older type Mac's, and the oscillator on Mac Plus's is
not OE, while the ones on the IIsi's and Quadra 700's are OE. Apple uses these
Output Enable oscillators so they can disable the oscillator and input their own
signal during testing. The Output Enable feature is not used in normal
operation. Printed on the crystal oscillator will be its manufacturer, model
number, and frequency.
The more recent Mac's use surface mount crystal oscillators that also have 4
pins, but they are in positions 3, 5, 10, and 12 if you follow the above 14 pin
package notation.
On the early Macs, the processor runs at half the speed of the oscillator, so a
20MHz Mac IIsi has a 40MHz crystal oscillator. The more recent Centris, Quadra,
and PowerMac computers use a crystal oscillator running at half the frequency of
the computer, so a PowerMac 6100/60 comes with a 30MHz oscillator.
There are several different modification techniques. They will all give you the
same final max speed. Some are just easier or more elegant than others. As with
all these modifications, even though there may be no visible sign that you
modified your Mac, you have voided the warranty on the Mac. As Apple states:
"This warranty does not apply if the product has been damaged by
accident, abuse, misuse, or misapplication; if the product has been
modified without the written permission of Apple; or if any Apple
serial number has been removed or defaced."
------------------------------------------------------------------------
This is what I seem to be finding. These numbers vary from Mac to Mac, so these
are just averages. Some machines will go faster than this. These are close to
the oscillators that Output Enablers ships in their kits. The problems noted are
those when above or near the top of the range listed. These problems are not
permanent, slowing down the computer will fix them.
Mac IIsi
Processor: 68030@20
Gestalt: 18
Initial Oscillator (MHz): 40
Max Oscillator (MHz): 50-55
Probs: Floppy Drive Controller
Mac IIfx
Processor: 68030@40
Gestalt: 13
Initial Oscillator (MHz): 80
Max Oscillator (MHz): 92.9405-100
Centris 610
Processor: 68LC040@20
Gestalt: 52
Initial Oscillator (MHz): 10
Max Oscillator with Serial (MHz): 14-14.31818
Max Oscillator w/o Serial (MHz): 15
Final Oscillator with PPC card & Serial (MHz): 14.2857
Probs: Serial Ports
Centris 650
Processor: 68040@25
Gestalt: 30
Initial Oscillator (MHz): 12.5
Max Oscillator with Serial (MHz): 14.31818-14.7456
Max Oscillator w/o Serial (MHz): 20
Probs: Serial Ports
Centris 650-mod
Processor: 68040@25
Gestalt: 36
Initial Oscillator (MHz): 12.5
Max Oscillator with Serial (MHz): 19-20
Final Oscillator with PPC card & Serial (MHz): 19.44755
Probs: Processor (crash)
Centris 660av
Processor: 68040@25
Gestalt: 60
Initial Oscillator (MHz): 12.5
Max Oscillator (MHz): 16-17.496
Probs: Video
Q605
Processor: 68LC040@25
Gestalt: 94
Gestalt at 20MHz: 93
Gestalt at 33MHz: 95
Q605 (LC475, P475, P476) Speedup
Quadra 610 (DOS)
Processor: 68040@25
Gestalt: 53
Initial Oscillator (MHz): 12.5
Max Oscillator with Serial (MHz): 14.7456-15
Max Oscillator w/o Serial (MHz): 18.5
Final Oscillator with PPC card & Serial (MHz): 16.96
Probs: Serial Ports
Quadra 650
Processor: 68040@33
Gestalt: 36
Initial Oscillator (MHz): 16.6667
Max Oscillator with Serial (MHz): 21-22
Max Oscillator w/o Serial (MHz): 24
Final Oscillator with PPC card & Serial (MHz): 19.6992
Probs: Serial Ports
Quadra 660av
Processor: 68040@25
Gestalt: 60
Initial Oscillator (MHz): 12.5
Max Oscillator (MHz): 16-17.496
Probs: Video
Quadra 700
Processor: 68040@25
Gestalt: 22
Initial Oscillator (MHz): 50
Max Oscillator (MHz): 66-70-74
Final Oscillator with PPC card & Serial (MHz): 74
Quadra 800
Processor: 68040@33
Gestalt: 35
Initial Oscillator (MHz): 16.6667
Max Oscillator with Serial (MHz): 20-21
Max Oscillator w/o Serial (MHz): 24
Final Oscillator with PPC card & Serial (MHz): 19.286
Probs: Serial Ports
Quadra 840av
Processor: 68040@40
Gestalt: 78
Initial Oscillator (MHz): 20
Max Oscillator (MHz): 23- 24
Probs: Serial Ports
Quadra 900
Processor: 68040@25
Gestalt: 20
Initial Oscillator (MHz): 50
Max Oscillator (MHz): 66-70-74
Final Oscillator with PPC card & Serial (MHz): 74
Quadra 950
Processor: 68040@33
Gestalt: 26
Initial Oscillator (MHz): 66
Max Oscillator (MHz): 80-92.9405
Final Oscillator with PPC card & Serial (MHz): 80
PowerMac 6100(av)
Processor: PPC 601@66, but runs at 60
Gestalt between 19.6608-60MHz: 75
Gestalt between 60.48-72.7272MHz: 100
Gestalt over 73.028MHz: 101
Initial Oscillator (MHz): 30
Max Oscillator (MHz): 40-42
Probs: Processor
PowerMac 7100(av)
Processor: PPC 601@66
Gestalt: 112
Gestalt at 60MHz: 111
Gestalt at 80MHz: 113
Initial Oscillator (MHz): 33
Max Oscillator (MHz): 40-42
Probs: Processor
PowerMac 8100(av)
Processor: PPC 601@80
Gestalt: 65
Gestalt at 60MHz: 61
Gestalt at 66MHz: 64
Gestalt at 100MHz: 66
Initial Oscillator (MHz): 40
Max Oscillator (MHz): 42-48
Probs: Processor
PowerBook 140
Processor: 68030@16
Gestalt: 25
Initial Oscillator (MHz): 33
Max Oscillator (MHz): 50
PowerBook 160
Processor: 68030@25
Gestalt: 134
Initial Oscillator (MHz): 50
Max Oscillator (MHz): 66
Duo 210
Processor: 68030@25
Gestalt: 29
Initial Oscillator (MHz): 50
Max Oscillator (MHz): 66
Duo 230
Processor: 68030@33
Gestalt: 32
Initial Oscillator (MHz): 66
Max Oscillator (MHz): 80
LCIII (P450)
Processor: 68030@25
Gestalt: 27
Gestalt at 33MHz: 62
LCIII (P450) Speedup
LC475 (P475, P476)
Processor: 68LC040@25
Gestalt: 89
Gestalt at 20MHz: TBA
Gestalt at 33MHz: 90
Q605 (LC475, P475, P476) Speedup
------------------------------------------------------------------------
Modification techniques:
Machine Mod-1 Mod-2 Mod-3
IIsi yes yes no
IIfx yes yes no
C610 yes no yes
C650 yes no yes
C650-mod yes no yes
C660av yes no yes
Q605 no no no
Q610 yes no yes
Q650 yes no yes
Q660av yes no yes
Q700 yes yes no
Q800 yes no yes
Q840av yes no yes
Q900 yes yes no
Q950 yes yes no
PM6100 yes no yes
PM7100 yes no yes
PM8100 yes no yes
PB140 yes no no
PB160 yes no no
Duo 210 yes no no
Duo 230 yes no no
LCIII no no no
------------------------------------------------------------------------
Mod-1
The basic idea of Modification #1 is removing the onboard oscillator, and
replacing it with a faster one. This is the mod most people use on the IIsi,
IIfx, Q700, Q900, & Q950, and more recently on the PB and Duo's.
First find the crystal oscillator by referring to the previous table and
description of its physical characteristics. Be careful when you remove the
oscillator. Most people just use a normal soldering iron, and are fine. A
grounded (three prong soldering iron) would be a bit safer. Use copper wick to
soak up the solder from all four pins, and pop out the proper oscillator.
Because the boards are multilayer, be careful not to damage anything; be gentle.
There was recently one report of a guy who damaged his IIsi board doing this.
But that was the only incident I have ever heard of, and lots and lots of people
have done this. I use a "desoldering iron". They melt the solder, and have an
electric pump to suck out the solder while you swirl the pin from the oscillator
around to get all the solder out. After you have done all 4, if you have done a
good job, the oscillator just pops out. If you have access to one of these
desoldering irons, I highly suggest you use it as it does a cleaner job, and
there is less risk of burning (discoloring) the board.
Instead of putting a new oscillator straight onto the board, it is nice to use a
socket so you can test your individual Mac, and see what the cutoff frequency
is, and you can always put the original oscillator back in the socket.
Take a 14 pin IC socket, remove all the pins but 1,7,8, and 14, and solder it
into the board. Make sure you put it in so pin 1 will go into pin 1, 2-2, 3-3,
4- 4. And the notch in the socket should face the same way the dot on the old
oscillator was facing. Now just put in a faster oscillator.
I have done this to a few IIsi, and the highest frequency we could get to work
without problems was 27.5MHz. Thus a speed increase from 20 to 27.5MHz. The
actual crystal is 55MHz (double the frequency). 55MHz TTL crystal oscillators do
exist, but they are rare. The thing most people seem to do is get a 55MHz CMOS
oscillator, and they work just fine. At 58.9 and above, there are problems with
the floppy drive; you cannot boot the Mac from a floppy, but other than that it
is fine until just over 30MHz. I recently had a IIsi at 28.3MHz and it was fine.
Be warned that some NuBus cards may not work after this modification. Most will
work at 25MHz, but will not at 27.5MHz, so just stick with 25MHz if that is the
case.
The IIsi and IIfx do not come with heatsinks, so to reduce the heat in the
processor, get a small heat sink to attach to the 68030 to cool it down; any
heat sink will do; the more surface area the faster heat will be dissipated. Be
careful when you put on the heat sink. Typically you'll use some heat transfer
grease, but the heat sink can slide off if the Mac is moved, and the heat sink
might short something out. The best thing seems to be to get a heat sink with a
hole in the middle, or drill one yourself, use the heat transfer grease, but
also put a small drop of super glue through the hole in the heat sink onto the
chip or put a drop on the side, and this should hold it in place. Super Glue is
brittle enough that you can pop off the heatsink later if you need to. Fry's
sells nice heat sink/fan combo's. They run $20 and up, and should keep the
processor cooler. They come with a Y cable to tap into your hard drive power
cable to power the fan. A more complete FAQ on this modification for a IIsi is
available via anonymous ftp from sumex-aim.stanford.edu in info-mac/info/hdwr
(iisi-25mhz-upgrade-faq.txt).
For the Quadra 700 and 900, you can get 70MHz TTL crystals from Fry's. The 70MHz
may not work, and you may have to back down to 66.6666MHz, the next most common
frequency. The Q700, Q900, and Q950 come with a heatsink installed. A more
complete file on this modification for a Quadra 700 is available via anonymous
ftp from sumex-aim.stanford.edu in info-mac/info/hdwr
(quadra-700-clock-mod-145.txt).
------------------------------------------------------------------------
Mod-2
The basic idea of Modification #2 is to disable the onboard oscillator with a
jumper and feed in a new signal on the back of the board. There are very few who
have performed this mod, but I feel it is more elegant and safer since you don't
have to remove the onboard oscillator. This newer, and less evasive method has
been performed on IIsi's & Q700's by myself and others, and should work fine on
the IIfx, Q900, and Q950.
The most difficult and risky part of "Mod-1" above is the removal of the
oscillator, and this is an alternative procedure that gets around that since the
crystal oscillators Apple uses have pin 1 as OE. On a crystal oscillator with
pin 1 as OE, if you ground pin 1, you disable the output from pin 3( 8) , and you
can feed a new signal into pin 3( 8) without removing the original crystal
oscillator.
Several months ago I performed this modification on a Quadra 700 by tacking
(soldering) a jumper on the back of the motherboard between pins 1 and 2(7) of
the 50MHz oscillator, and ran wires about 8 inches long each from pins 2(7),
3( 8) , and 4(14) to a 14 pin socket attached to the inside of the Q700 with pins
in positions 7, 8, and 14. Into this we placed a 70MHz crystal oscillator and
later a 74MHz oscillator. This modification is nice in that it is a bit less
risky as far as damage to the motherboard, but you have to be careful to use
thin wires in order to make clean solder joints. With this modification you
could remove the wires at a later date to return to the original configuration
more cleanly.
------------------------------------------------------------------------
Mod-3
The basic idea of modification #3 is building a clip that disables the onboard
oscillator, and feeds in a new, faster signal. The beauty of this modification
over the others is that you do not have to do any soldering on the motherboard
itself, just on the part you clip onto the surface mount crystal oscillator in
your Mac. This is the modification most people use on the C610, C650, C660av,
Q610, Q650, Q660av, Q800, Q840av, PM6100(av), PM7100(av), and PM8100(av). It
will only work on machines with surface mount crystal oscillators.
The really neat thing about this came into play in February 1992 when Apple
released the Centris 610, 650, and Quadra 800. In these machines and since,
Apple has been using surface mount crystal oscillators. Now that Apple was using
surface mount crystal oscillators, there was plenty of accessible area on the
metal tabs of the oscillator. In June '93 Guy Kuo reported the first crystal
swap of sorts on a Centris 610 to the net. He soldered pins 3, 5, 10, and 12 of
a 14 pin socket directly onto the surface mount crystal oscillator. Because the
pins on a standard 14 pin package TTL crystal oscillator are at positions 1, 7,
8, and 14, he made jumpers between pins 5-7, 8-10, and 12-14. He disabled the
on-board surface mount crystal oscillator with a jumper between 3-5. Then put
the new crystal in the socket. The complete text of his work is available via
anonymous ftp from sumex-aim.stanford.edu in info-mac/info/hdwr
(centris-610-clock-mod-11).
I was a little hesitant about soldering onto my new Quadra 800, so wrote to him
a few days later about using a 3M Surface Mount Test Clip, and asked his
thoughts. He suspected I could not find a reasonable test clip, but otherwise
agreed it would work. A few days later the 3M SOIC test clip arrived, and the
test clip worked perfectly. I was running my Quadra 800 at 40MHz with no
problems, and best of all the modification was all contained in a simple little
clip that could be removed without trace at will. And thus the removable test
clip approach was born. My Q800 even worked at 48MHz as long as I did not access
the serial ports. A few days later I got several crystals, and found the highest
frequency on my Quadra 800 to be 42.0MHz. Since then I've tried it at
42.1052MHz, and the serial ports did not work, so the cutoff for my Q800 was at
42.0MHz. If you never use your serial ports, 48MHz worked fine for me, while at
50MHz my Mac was not happy and would not boot.
So if you are still interested, you will need a surface mount test clip; 3M and
Pomona make them, and I prefer the 3M ones. Make sure you get a surface mount
test clip. The I.C. test clips also work, but I prefer the surface mount SOIC
(small outline integrated circuit) ones. A 10, 12, 14, 16, or 18 pin clip will
be fine. I'd say go with a 14 or 16 pin narrow or wide clip. I used to recommend
the gold coated ones, but the resistance/corrosion effect is minimal over the
alloy ones. You will also need a 14 pin IC socket, there are plenty of types.
The machined pin ones are nice because you can pop out the pins that are not
needed to get them out of the way since you only need three pins in the socket.
(Yes, just three, pin one on the new oscillator is not going to be used) You
will also need an oscillator (more on this later), a little wire, soldering
iron, solder, and possibly a heat sink and or fan depending on the machine. For
a C610, C660av, Q610, and Q660av you should add a heat sink. And you will want a
fan with the PM's.
The others already have heat sinks, and do not get too hot. I had an extra fan
with my Q800, but removed it, and it has been fine. The heat sinks come with the
clips needed to attach them to the chip. These are a bit of a pain, you just
have to work at it for a while. There may be several ways to do it, but I just
slide the clips on from the side. Sometimes they fall off half way there, but
eventually it works. Some people have been using the heat sink/fan combo's.
The new Q610 and Q660av computers are based on a new mask of the 68040 (There is
an "H" after the '040 and before the "RC") that runs cooler at 25MHz, so it
comes at 25MHz without a heatsink. This is the same mask as the C660av and
Q840av uses. If you do the modification on them it would still be best to add a
heat sink.
How to put it all together:
Stand the clip so it's jaws are facing down, and the rows of pins go from left
to right, and call the closer row A and the further row B. Number the pins from
left to right 1 through 7 (for the 14 pin clip). Next place the 14 pin IC socket
with the pins down, and the notch to the left, and number the pins as 1, 2, 3,
4, 5, 6, 7 in the row closest to you, going left to right. The other row is
numbered 8, 9, 10, 11, 12, 13, 14 as you go right to left (back towards the
notch).
Now starting with the test clip, remove all the pins but four, leaving pins in
positions A2, A6, B2, and B6. Next solder a little jumper wire between pins A2
and A6. Now get the 14 pin IC socket, and remove all the pins but 7, 8, and 14.
Solder a jumper wire from pin 7 on the IC socket to the jumpered pins on the
clip, either A2 or A6 will do. Also solder a jumper wire from pin 8 to pin B6,
and pin 14 to pin B2. If you get the narrow clip, you may want to replace the
spring with one with less tension; they are like $0.30 at hardware stores, and I
cut them into two springs. This way you don't have to push so hard, and it is
easier to position on the motherboard. Now put the crystal in the socket with
pin 1 in 1, 2 in 2, 3 in 3 and 4 in 4.
There are several surface mount oscillators used on the motherboards. The proper
surface mount crystal oscillator on the mother board will have a frequency on it
half that of your computer and can be determined from the previous table.
That is it, now you just clamp it onto the surface mount crystal oscillator with
the notch on the socket facing the same way as the surface mount crystal
oscillator. And watch to make sure the little pins clamp onto the surface mount
chip. You may want to use a flashlight for this. These clips hang on very, very
well, I've never had mine move in the last year and a half, nor any of the other
ones I've done.
Now just turn on your computer and enjoy the speed.
------------------------------------------------------------------------
Centris 610 Ethernet Problems:
Those Centris 610's that have onboard ethernet capability share the 10MHz
oscillator with the CPU. If you replace that oscillator with a different one,
your ethernet will no longer work. In January, Eckart Hasselbrink
(Hasselbrink@fhi-berlin.mpg.de) posted a fairly simple hardware modification to
fix this to comp.sys.mac.hardware. So if you plan to use your ethernet on your
Centris 610 and speed it up, you will need to perform Eckart's C610 Ethernet
Modification first.
------------------------------------------------------------------------
PowerMac's:
I have done several PowerMacs, and their top speeds vary quite a bit. The max I
ever got with a PM6100 was 90MHz, but that was a rare case. At 84MHz the PPC601
overheats quite rapidly. With a cool hairdryer cooling the heatsink on the 601,
it worked fine, but was a bit noisy
. A 12 volt DC 40mm x 40mm brushless fan
will fit snugly inside the heatsink on the PPC601 chip.
Be very careful when you insert the fan into the heatsink on the PPC. If you
press down too hard you may damage the processor itself, and destroy your
computer. Be very gentle; if the fan will not slide in rest the fan on top of
the heatsink, and gently separate the fins of the heatsink to allow the fan to
drop into place.
PM7100(av):
The oscillator you need to grab onto in the PM7100 is located below the
power supply and there is only a small amount of room. You will need to
decapitate the clip prior to wiring it up to get it to fit.
PM8100(av):
You will need a similarly short clip for the PM8100 You will also need to
shave off some of the plastic clip on the computer that holds the
motherboard to the case if you use one of these clips.
Apple's PPC PDS Card
If you have an Apple PPC PDS card installed in one of the above machines
that can be accelerated with these modifications, the card will run at
double the speed of the 68040 processor. The upper limit however is often a
bit lower as the card typically cannot go above approximately 76MHz. See
the above table for exact frequencies. If you accelerate one of these
cards, you should put some extra cooling device(s) on the giant heatsink
unless you use it as a frying pan to cook on. Two fans mounted on extruded
heatsinks and mounted on the card work wonders (no more burns when you pull
out the card).
------------------------------------------------------------------------
Testing the Modification
See the table of machines for information on the typical problems when you are
going too fast. If the problem is with the serial ports, there is little you can
do other than slow down a little. A problem with the serial ports will be
obvious as your computer will hang up or crash when you access your modem or
printer ports. There is a modification to fix the serial port problem on the
C650, and with a little poking around one might be able to come up with
modifications for the other machines to fix these serial port problems.
The video problem on the 660's typically appears as video redraw problems where
the cursor leaves a trace, or the screen does not properly redraw when a window
is closed. James Wang (jwang@soda.berkeley.edu), maintainer of the AV FAQ
(ftp://ftp.csua.berkeley.edu/pub/jwang/av-faq-15.rtf.sit.hqx), recommends
placing small heatsinks on the onboard VRAM to help cool them down as they get
quite warm.
The speed of the memory is also important, so if you plan to boost your Mac very
far, you may need faster SIMM's. It is said that composite SIMMs slow you down
by about 10ns, so if you must get composite SIMMs, get them 10ns faster than you
would have.
To test out the modification, the best thing to do is just use it a while. You
can run Speedometer 4.0 (available via anonymous ftp from cag-www.lcs.mit.edu in
HyperArchive/Archive/cfg) to see the changes. I use Snooper with the serial port
loopback plugs to check the serial ports to find their limits; Snooper also
tells you what frequency you are running at in round numbers. Snooper is no
longer sold, but parts seem to have been incorporated into the latest version of
Norton Utilities, 3.1. The last version of MacCheck, 1.0.5, properly reports the
computer frequency, but Apple has pulled it from all their sites "due to high
support call traffic". TattleTech 2.15 and the updater to TattleTech 2.17 are
now available via anonymous ftp from cag-www.lcs.mit.edu in
HyperArchive/Archive/cfg, and it properly reports the speed of the processor.
If the clip is only half on the computer will not start up. It may be disabling
the surface mount oscillator, but not replacing its signal. If this is the case,
just remove the clip, reposition, and try again.
If the clip missed the surface mount oscillator the computer will start up, but
at its normal frequency. If this is the case, remove the clip, reposition, and
try again.
If the jumper on the clip is broken you will be feeding two frequencies into the
PLL, and it will not be able to lock onto the frequency, and the computer will
not start. To check this, remove the oscillator from the clip, and clip the clip
onto the surface mount oscillator. Try to start the computer; it should not
start. If it does, your jumper wire is broken, or you put the clip on wrong.
If your Mac does not give the standard chime at startup it means your clip is
only half on, or the oscillator is too fast.
------------------------------------------------------------------------
C650 Serial Port Modification:
Using the above clips, the max frequency for a Centris 650 is about 30MHz before
you encounter serial port problems. Marlin Prowell (mbp@janus.com) following up
on a hunch by James McPhail (jmacphai@cue.bc.ca) looked into the differences
between the C650 and Q800 motherboards in hopes that a simple modification might
enable the serial ports to function properly at 33MHz (Q800 normal frequency) or
higher. On the bottom of the motherboard, under the IOSB chip, Marlin found two
differences.
R151 is installed on the C650's, and is missing on the Q800's.
R152 is missing on the C650's, and is installed on the Q800.
R151 is a 300 ohms resistor and R152 is a 1.2k ohm resistor. Looking at the
bottom of the board, with the back away from you, R151 is 3 3/4" from the right,
and 3" down. The tabs for R152 are 4" from the right, and 3" down. R151 is
black, and says 301 on it.
Marlin felt that R151 was glued to the board, and just using solder braid he was
unable to remove the resistor for fear that prying it off may damage the two
traces that run under it. Heating the resistor with a soldering iron Marlin was
eventually able to soften the glue and remove the resistor. Or you can use James
McPhail's two soldering iron Western technique with a soldering iron in each
hand to heat each side simultaneously and flip the resistor off the board. Now
just add the R152. Marlin suggests holding the surface mount resistor in place
with a small screwdriver while soldering it to the exposed pads on the board.
Marlin has since used both the serial and modem ports error free while running
his C650 at 40MHz, and MacCheck reports no problems. He has also checked to make
sure the ethernet works, and it does. Since Marlin's initial modification, it
has been confirmed by at least one hundred people. On some of these Mac's the
CPU overheats after a while, so Marlin suggests you add a fan to dissipate the
heat faster from the heatsink. You can also just run a bit slower, say 38MHz.
You can purchase these 1.2k resistors from Digi-Key, but the minimum order is
200 of them. If you e-mail your US mailing address to Output Enablers at
oenabler@netcom.com, they will send you a free resistor left over from Marlin's
extra 199. OE has obtained some more as over 200 people have performed the
modification with Marlin's spare resistors.
This modification makes your Mac think it has become a Quadra 650, and the
Quadra 650 did not exist when most of you purchased your Centris 650. The System
Enabler 040 that came with your Centris 650, version 1.0, will not work after
this modification, and your Mac will not start up unless you have already
updated the System Enabler 040 to version 1.1, the current version. The System
Enabler 040 version 1.1 is available from your local Apple Dealer, or you can
ftp it from bric-a-brac.apple.com in /dts/mac/sys.soft/7.1.system.enablers.
Marlin suggests you also put the new Enabler on all your recovery utility disks
as well so you will be prepared next time something goes wrong. The System
Enabler is incorporated into System 7.5, so you need not obtain the new Enabler
if you are running System 7.5.
------------------------------------------------------------------------
PowerBook 140 Modification
A few companies have been replacing the crystal oscillator in PowerBooks to
speed them up, and add a 68882 math coprocessor. If you are good with a
soldering iron you might give Glenn Nelson (gwnelson@tddcae99.tddeng00.fnts.com)
and Jerry Cupples' (jcupples@iphase.com) PowerBook 140 Modification a try.
------------------------------------------------------------------------
Duo Clip
If you are interested in speeding up your Duo 210 or 230 without any soldering
on the motherboard you might give Ronald Leenes' (r.e.leenes@bsk.utwente.nl) Duo
Clip a try.
------------------------------------------------------------------------
Address' for some parts suppliers:
Fry's Electronics
340 Portage Ave
Palo Alto, CA
(415) 496-6000
12 volt DC 40mm x 40mm brushless fan
about $10-15
14, 18.432, 19.6608, 25.175, 28.322MHz Oscillators
$2.99
70MHz Oscillator
$6.49
Digi-Key
(800) 344-4539
14 pin IC socket w/tin pins
Part# ED3114
$0.57
3M Surface Mount Test Clip
14pin
Part# 923650-14-ND
$7.83
16pin
Part# 923650-16-ND
$8.28
68040 Heat sinks
0.250
Part# HS159-ND
$3.84
0.350
Part# HS147-ND
$3.94
0.600
Part# HS160-ND
$3.98
Crystal Oscillators
14.31818MHz Oscillator
Part# CTX115-ND
$3.25
14.7456MHz Oscillator
Part# X127-ND
$3.38
16MHz Oscillator
Part# CTX116-ND
$3.25
16.257MHz Oscillator
Part# X128-ND
$3.38
18MHz Oscillator
Part# X117-ND
$3.38
18.432MHz Oscillator
Part# CTX118-ND
$3.25
19.6608MHz Oscillator
Part# CTX124-ND
$3.25
20MHz Oscillator
Part# CTX119-ND
$3.25
24MHz Oscillator
Part# CTX125-ND
$3.25
25MHz Oscillator
Part# CTX126-ND
$3.25
25.175MHz Oscillator
Part# CTX127-ND
$3.25
28.322MHz Oscillator
Part# CTX128-ND
$3.25
30MHz Oscillator
Part# XC316-ND
$4.02
32MHz Oscillator
Part# CTX129-ND
$3.25
32.514MHz Oscillator
Part# X133-ND
$3.38
35MHz Oscillator
Part# X134-ND
$3.38
40MHz Oscillator
Part# CTX120-ND
$3.25
48MHz Oscillator
Part# X135-ND
$3.38
50MHz Oscillator
Part# CTX121-ND
$3.25
50MHz Surface Mount Oscillator
Part# SE2325
$6.53
55MHz CMOS Oscillator
Part# SE1509
$3.60
64MHz Oscillator
Part# X136-ND
$3.88
66.6666MHz Oscillator
Part# CTX137-ND
$4.45
80MHz Oscillator
Part# CTX138-ND
$10.01
Active Electronics
(800) 228-4836
33MHz 68882
Part# MC68882-FN33A
$76.95 plus S&H
Output Enablers
1678 Shattuck Ave. Suite # 247
Berkeley, CA 94709
oenabler@netcom.com
$50-$60/kit
Output Enablers sells kits for the C610, C650, C660av, Q610, Q650, Q660av,
Q800, Q840av, PM6100(av), PM7100(av). They also stock other supplies
including those for the IIsi, Q700, Q900, Q950, PB140, PB160, Duo210,
Duo230, C610 ethernet, and C650 serial port modifications.
------------------------------------------------------------------------
If you have any questions or comments that should be added to this, feel free to
e-mail me.
And a big thanks to everyone who has contributed to this file.
Marc Schrier
schrier@garnet.berkeley.edu
Disclaimer: I have been providing this info for quite some time, and I am now
associated with Output Enablers. I would like to continue to update and maintain
this unbiased information as long as there is interest on the internet. Any
opinions represented here are mine, not necessarily those of Output Enablers.
------------------------------------------------------------------------
Copyright © 1993-4, Marc Schrier
Please contact me prior to distributing or reproducing this file.
----------
Mac Crystal Oscillator Speedup History 2.5b
November 1994
------------------------------------------------------------------------
There has been a great deal of interest expressed over the net about these
simple and inexpensive Macintosh modifications that yield 20-60% speed
increases. Over the last two years I have been doing a fair amount of crystal
oscillator swapping/acceleration on Mac's, and gathering information from
others. I've made several posts to comp.sys.mac.hardware with the bulk of this
info and as new machines come out, and new concerns surface, I will try to add
them to this history of the modifications, post them on comp.sys.mac.hardware
and make them available for anonymous ftp on sumex-aim.stanford.edu and its
mirrors in /info-mac/info/hdwr. Included in this version are some more stats on
the PowerMac's and on the Apple PPC PDS card in the Centris' and Quadra's. I've
also started a Clock Chipping Home Page which has the latest history file, and
several other useful files. The URL is:
http://bambam.cchem.berkeley.edu/~schrier/mhz.html
------------------------------------------------------------------------
A little background:
All computers operate at a certain frequency with which operations are
performed. Within a certain class of computers, for example Mac's with a 68030
processor, the higher the frequency, the higher frequency of operations
processed, and the faster the computer provided there is no other speed
effecting hardware like a cache or slow data path. The designer of the computer,
Apple in this case, will use components that are rated at the same frequency or
faster than the final computer will be. In this case the 68030's are made by
Motorola. All 68030's are generally alike in what they do, but they are not
alike in how fast they can do it. Motorola sells several 68030 processors rated
at 16, 20, 25, 33, 40 and 50MHz for Mac's, accelerators and such. A large
frequency difference will require a different mask during production of the
processor, but small changes may not. Motorola only needs to guarantee that the
chip they mark as 20MHz will function properly at 20MHz under a variety of
conditions. Some chip vendors will test parts at different frequencies and sort
the chips accordingly while others may just label the them at will and sell the
chips at the different price as long as they are within the specifications.
Because of this it is reasonable that the 20 and 25's actually come from the
same batch, are separated on demand, and tested to make sure they will withstand
that frequency. And thus it is reasonable that a 20MHz processor will function
fine at a higher frequency, say 25MHz. Running the 20MHz part at 25MHz will
generate more heat than at 20MHz, but no more than the 25MHz part if they came
from the same production mask.
Many of the components in the computer need to be synchronized, so a fundamental
frequency is generated by a crystal oscillator to synchronize them. Other parts
like NuBus cards and video do not have to be the same frequency, so they may
have separate crystal oscillators. A typical computer may have three crystal
oscillators to clock different groups of components on the motherboard. Provided
the components that are clocked by a particular crystal oscillator are capable
of a speed increase, that crystal oscillator may be replaced with one of a
higher frequency. How much a specific Mac can be sped up by this method depends
on how the motherboard was designed, the components used, and what things the
crystal oscillator that controls the processor also controls. With some of the
newer Mac's, there are a few MHz differences in the top speeds reported for the
same model, so part of this is luck of the draw.
This crystal oscillator swapping has been done for years, and some early
computers even had jumpers that made it really easy to disable one oscillator
and enable another higher frequency one. The first Mac's to be modified were the
IIsi's. A stock IIsi's runs at 20MHz, and IIci's at 25MHz, and since the
architecture of these machines was so similar it seemed reasonable to run a IIsi
at IIci speeds. Another important factor was that earlier Mac's had just one
crystal oscillator that controlled everything, and if you replaced it you would
mess things up. The IIsi was different as some noted through its frequency
deviation from its 8 and 16MHz precursors where the main frequency was halved
and quartered to run the CPU, serial ports, video... The IIsi was different, it
had 4 crystal oscillators, only one of which controlled the processor speed.
The Crystal Oscillator:
The type of crystal oscillator in the early Mac's is a full size, 14 pin
package, TTL type crystal oscillator. It is a rectangular metal can, with
approximate dimensions of 2.0 x 1.3cm and typically about 0.3-0.6cm high. All
crystal oscillators have at least 4 pins. Some are numbered 1,2,3,4 and others
1,7,8,14. Pin 1 is always the pin next to the pointed edge (the others are
rounded), with the dot, or next to the indentation on the newer CMOS, or surface
mount crystal oscillators. With the pins facing down, put the dot, or
indentation to your left, and the pin on the left, closest to you is pin 1.
Going counter clockwise, pin 2 (or 7, depending on what numbering scheme) is to
the right, pin 3( 8) right side and further away, and 4(14) left side, and
further away. Pin 1 on all the newer Mac's with surface mount crystal
oscillators, and some of the older ones is an output enable/disable pin (OE). On
some of the crystal oscillators you purchase pin 1 will be OE, yet on many it
will not be used (no contact (NC)). It is not important which you get as you
will not be using the output enable feature on the new oscillator. If you ground
pin one with a jumper to pin 2(7) on an OE oscillator you disable the
oscillator. Pin 2(7) is a ground. Pin 3( 8) is the output. Pin 4(14) is the
supply voltage, +5 VDC.
I've checked a few of the older type Mac's, and the oscillator on Mac Plus's is
not OE, while the ones on the IIsi's and Quadra 700's are OE. Apple uses these
Output Enable oscillators so they can disable the oscillator and input their own
signal during testing. The Output Enable feature is not used in normal
operation. Printed on the crystal oscillator will be its manufacturer, model
number, and frequency.
The more recent Mac's use surface mount crystal oscillators that also have 4
pins, but they are in positions 3, 5, 10, and 12 if you follow the above 14 pin
package notation.
On the early Macs, the processor runs at half the speed of the oscillator, so a
20MHz Mac IIsi has a 40MHz crystal oscillator. The more recent Centris, Quadra,
and PowerMac computers use a crystal oscillator running at half the frequency of
the computer, so a PowerMac 6100/60 comes with a 30MHz oscillator.
There are several different modification techniques. They will all give you the
same final max speed. Some are just easier or more elegant than others. As with
all these modifications, even though there may be no visible sign that you
modified your Mac, you have voided the warranty on the Mac. As Apple states:
"This warranty does not apply if the product has been damaged by
accident, abuse, misuse, or misapplication; if the product has been
modified without the written permission of Apple; or if any Apple
serial number has been removed or defaced."
------------------------------------------------------------------------
This is what I seem to be finding. These numbers vary from Mac to Mac, so these
are just averages. Some machines will go faster than this. These are close to
the oscillators that Output Enablers ships in their kits. The problems noted are
those when above or near the top of the range listed. These problems are not
permanent, slowing down the computer will fix them.
Mac IIsi
Processor: 68030@20
Gestalt: 18
Initial Oscillator (MHz): 40
Max Oscillator (MHz): 50-55
Probs: Floppy Drive Controller
Mac IIfx
Processor: 68030@40
Gestalt: 13
Initial Oscillator (MHz): 80
Max Oscillator (MHz): 92.9405-100
Centris 610
Processor: 68LC040@20
Gestalt: 52
Initial Oscillator (MHz): 10
Max Oscillator with Serial (MHz): 14-14.31818
Max Oscillator w/o Serial (MHz): 15
Final Oscillator with PPC card & Serial (MHz): 14.2857
Probs: Serial Ports
Centris 650
Processor: 68040@25
Gestalt: 30
Initial Oscillator (MHz): 12.5
Max Oscillator with Serial (MHz): 14.31818-14.7456
Max Oscillator w/o Serial (MHz): 20
Probs: Serial Ports
Centris 650-mod
Processor: 68040@25
Gestalt: 36
Initial Oscillator (MHz): 12.5
Max Oscillator with Serial (MHz): 19-20
Final Oscillator with PPC card & Serial (MHz): 19.44755
Probs: Processor (crash)
Centris 660av
Processor: 68040@25
Gestalt: 60
Initial Oscillator (MHz): 12.5
Max Oscillator (MHz): 16-17.496
Probs: Video
Q605
Processor: 68LC040@25
Gestalt: 94
Gestalt at 20MHz: 93
Gestalt at 33MHz: 95
Q605 (LC475, P475, P476) Speedup
Quadra 610 (DOS)
Processor: 68040@25
Gestalt: 53
Initial Oscillator (MHz): 12.5
Max Oscillator with Serial (MHz): 14.7456-15
Max Oscillator w/o Serial (MHz): 18.5
Final Oscillator with PPC card & Serial (MHz): 16.96
Probs: Serial Ports
Quadra 650
Processor: 68040@33
Gestalt: 36
Initial Oscillator (MHz): 16.6667
Max Oscillator with Serial (MHz): 21-22
Max Oscillator w/o Serial (MHz): 24
Final Oscillator with PPC card & Serial (MHz): 19.6992
Probs: Serial Ports
Quadra 660av
Processor: 68040@25
Gestalt: 60
Initial Oscillator (MHz): 12.5
Max Oscillator (MHz): 16-17.496
Probs: Video
Quadra 700
Processor: 68040@25
Gestalt: 22
Initial Oscillator (MHz): 50
Max Oscillator (MHz): 66-70-74
Final Oscillator with PPC card & Serial (MHz): 74
Quadra 800
Processor: 68040@33
Gestalt: 35
Initial Oscillator (MHz): 16.6667
Max Oscillator with Serial (MHz): 20-21
Max Oscillator w/o Serial (MHz): 24
Final Oscillator with PPC card & Serial (MHz): 19.286
Probs: Serial Ports
Quadra 840av
Processor: 68040@40
Gestalt: 78
Initial Oscillator (MHz): 20
Max Oscillator (MHz): 23- 24
Probs: Serial Ports
Quadra 900
Processor: 68040@25
Gestalt: 20
Initial Oscillator (MHz): 50
Max Oscillator (MHz): 66-70-74
Final Oscillator with PPC card & Serial (MHz): 74
Quadra 950
Processor: 68040@33
Gestalt: 26
Initial Oscillator (MHz): 66
Max Oscillator (MHz): 80-92.9405
Final Oscillator with PPC card & Serial (MHz): 80
PowerMac 6100(av)
Processor: PPC 601@66, but runs at 60
Gestalt between 19.6608-60MHz: 75
Gestalt between 60.48-72.7272MHz: 100
Gestalt over 73.028MHz: 101
Initial Oscillator (MHz): 30
Max Oscillator (MHz): 40-42
Probs: Processor
PowerMac 7100(av)
Processor: PPC 601@66
Gestalt: 112
Gestalt at 60MHz: 111
Gestalt at 80MHz: 113
Initial Oscillator (MHz): 33
Max Oscillator (MHz): 40-42
Probs: Processor
PowerMac 8100(av)
Processor: PPC 601@80
Gestalt: 65
Gestalt at 60MHz: 61
Gestalt at 66MHz: 64
Gestalt at 100MHz: 66
Initial Oscillator (MHz): 40
Max Oscillator (MHz): 42-48
Probs: Processor
PowerBook 140
Processor: 68030@16
Gestalt: 25
Initial Oscillator (MHz): 33
Max Oscillator (MHz): 50
PowerBook 160
Processor: 68030@25
Gestalt: 134
Initial Oscillator (MHz): 50
Max Oscillator (MHz): 66
Duo 210
Processor: 68030@25
Gestalt: 29
Initial Oscillator (MHz): 50
Max Oscillator (MHz): 66
Duo 230
Processor: 68030@33
Gestalt: 32
Initial Oscillator (MHz): 66
Max Oscillator (MHz): 80
LCIII (P450)
Processor: 68030@25
Gestalt: 27
Gestalt at 33MHz: 62
LCIII (P450) Speedup
LC475 (P475, P476)
Processor: 68LC040@25
Gestalt: 89
Gestalt at 20MHz: TBA
Gestalt at 33MHz: 90
Q605 (LC475, P475, P476) Speedup
------------------------------------------------------------------------
Modification techniques:
Machine Mod-1 Mod-2 Mod-3
IIsi yes yes no
IIfx yes yes no
C610 yes no yes
C650 yes no yes
C650-mod yes no yes
C660av yes no yes
Q605 no no no
Q610 yes no yes
Q650 yes no yes
Q660av yes no yes
Q700 yes yes no
Q800 yes no yes
Q840av yes no yes
Q900 yes yes no
Q950 yes yes no
PM6100 yes no yes
PM7100 yes no yes
PM8100 yes no yes
PB140 yes no no
PB160 yes no no
Duo 210 yes no no
Duo 230 yes no no
LCIII no no no
------------------------------------------------------------------------
Mod-1
The basic idea of Modification #1 is removing the onboard oscillator, and
replacing it with a faster one. This is the mod most people use on the IIsi,
IIfx, Q700, Q900, & Q950, and more recently on the PB and Duo's.
First find the crystal oscillator by referring to the previous table and
description of its physical characteristics. Be careful when you remove the
oscillator. Most people just use a normal soldering iron, and are fine. A
grounded (three prong soldering iron) would be a bit safer. Use copper wick to
soak up the solder from all four pins, and pop out the proper oscillator.
Because the boards are multilayer, be careful not to damage anything; be gentle.
There was recently one report of a guy who damaged his IIsi board doing this.
But that was the only incident I have ever heard of, and lots and lots of people
have done this. I use a "desoldering iron". They melt the solder, and have an
electric pump to suck out the solder while you swirl the pin from the oscillator
around to get all the solder out. After you have done all 4, if you have done a
good job, the oscillator just pops out. If you have access to one of these
desoldering irons, I highly suggest you use it as it does a cleaner job, and
there is less risk of burning (discoloring) the board.
Instead of putting a new oscillator straight onto the board, it is nice to use a
socket so you can test your individual Mac, and see what the cutoff frequency
is, and you can always put the original oscillator back in the socket.
Take a 14 pin IC socket, remove all the pins but 1,7,8, and 14, and solder it
into the board. Make sure you put it in so pin 1 will go into pin 1, 2-2, 3-3,
4- 4. And the notch in the socket should face the same way the dot on the old
oscillator was facing. Now just put in a faster oscillator.
I have done this to a few IIsi, and the highest frequency we could get to work
without problems was 27.5MHz. Thus a speed increase from 20 to 27.5MHz. The
actual crystal is 55MHz (double the frequency). 55MHz TTL crystal oscillators do
exist, but they are rare. The thing most people seem to do is get a 55MHz CMOS
oscillator, and they work just fine. At 58.9 and above, there are problems with
the floppy drive; you cannot boot the Mac from a floppy, but other than that it
is fine until just over 30MHz. I recently had a IIsi at 28.3MHz and it was fine.
Be warned that some NuBus cards may not work after this modification. Most will
work at 25MHz, but will not at 27.5MHz, so just stick with 25MHz if that is the
case.
The IIsi and IIfx do not come with heatsinks, so to reduce the heat in the
processor, get a small heat sink to attach to the 68030 to cool it down; any
heat sink will do; the more surface area the faster heat will be dissipated. Be
careful when you put on the heat sink. Typically you'll use some heat transfer
grease, but the heat sink can slide off if the Mac is moved, and the heat sink
might short something out. The best thing seems to be to get a heat sink with a
hole in the middle, or drill one yourself, use the heat transfer grease, but
also put a small drop of super glue through the hole in the heat sink onto the
chip or put a drop on the side, and this should hold it in place. Super Glue is
brittle enough that you can pop off the heatsink later if you need to. Fry's
sells nice heat sink/fan combo's. They run $20 and up, and should keep the
processor cooler. They come with a Y cable to tap into your hard drive power
cable to power the fan. A more complete FAQ on this modification for a IIsi is
available via anonymous ftp from sumex-aim.stanford.edu in info-mac/info/hdwr
(iisi-25mhz-upgrade-faq.txt).
For the Quadra 700 and 900, you can get 70MHz TTL crystals from Fry's. The 70MHz
may not work, and you may have to back down to 66.6666MHz, the next most common
frequency. The Q700, Q900, and Q950 come with a heatsink installed. A more
complete file on this modification for a Quadra 700 is available via anonymous
ftp from sumex-aim.stanford.edu in info-mac/info/hdwr
(quadra-700-clock-mod-145.txt).
------------------------------------------------------------------------
Mod-2
The basic idea of Modification #2 is to disable the onboard oscillator with a
jumper and feed in a new signal on the back of the board. There are very few who
have performed this mod, but I feel it is more elegant and safer since you don't
have to remove the onboard oscillator. This newer, and less evasive method has
been performed on IIsi's & Q700's by myself and others, and should work fine on
the IIfx, Q900, and Q950.
The most difficult and risky part of "Mod-1" above is the removal of the
oscillator, and this is an alternative procedure that gets around that since the
crystal oscillators Apple uses have pin 1 as OE. On a crystal oscillator with
pin 1 as OE, if you ground pin 1, you disable the output from pin 3( 8) , and you
can feed a new signal into pin 3( 8) without removing the original crystal
oscillator.
Several months ago I performed this modification on a Quadra 700 by tacking
(soldering) a jumper on the back of the motherboard between pins 1 and 2(7) of
the 50MHz oscillator, and ran wires about 8 inches long each from pins 2(7),
3( 8) , and 4(14) to a 14 pin socket attached to the inside of the Q700 with pins
in positions 7, 8, and 14. Into this we placed a 70MHz crystal oscillator and
later a 74MHz oscillator. This modification is nice in that it is a bit less
risky as far as damage to the motherboard, but you have to be careful to use
thin wires in order to make clean solder joints. With this modification you
could remove the wires at a later date to return to the original configuration
more cleanly.
------------------------------------------------------------------------
Mod-3
The basic idea of modification #3 is building a clip that disables the onboard
oscillator, and feeds in a new, faster signal. The beauty of this modification
over the others is that you do not have to do any soldering on the motherboard
itself, just on the part you clip onto the surface mount crystal oscillator in
your Mac. This is the modification most people use on the C610, C650, C660av,
Q610, Q650, Q660av, Q800, Q840av, PM6100(av), PM7100(av), and PM8100(av). It
will only work on machines with surface mount crystal oscillators.
The really neat thing about this came into play in February 1992 when Apple
released the Centris 610, 650, and Quadra 800. In these machines and since,
Apple has been using surface mount crystal oscillators. Now that Apple was using
surface mount crystal oscillators, there was plenty of accessible area on the
metal tabs of the oscillator. In June '93 Guy Kuo reported the first crystal
swap of sorts on a Centris 610 to the net. He soldered pins 3, 5, 10, and 12 of
a 14 pin socket directly onto the surface mount crystal oscillator. Because the
pins on a standard 14 pin package TTL crystal oscillator are at positions 1, 7,
8, and 14, he made jumpers between pins 5-7, 8-10, and 12-14. He disabled the
on-board surface mount crystal oscillator with a jumper between 3-5. Then put
the new crystal in the socket. The complete text of his work is available via
anonymous ftp from sumex-aim.stanford.edu in info-mac/info/hdwr
(centris-610-clock-mod-11).
I was a little hesitant about soldering onto my new Quadra 800, so wrote to him
a few days later about using a 3M Surface Mount Test Clip, and asked his
thoughts. He suspected I could not find a reasonable test clip, but otherwise
agreed it would work. A few days later the 3M SOIC test clip arrived, and the
test clip worked perfectly. I was running my Quadra 800 at 40MHz with no
problems, and best of all the modification was all contained in a simple little
clip that could be removed without trace at will. And thus the removable test
clip approach was born. My Q800 even worked at 48MHz as long as I did not access
the serial ports. A few days later I got several crystals, and found the highest
frequency on my Quadra 800 to be 42.0MHz. Since then I've tried it at
42.1052MHz, and the serial ports did not work, so the cutoff for my Q800 was at
42.0MHz. If you never use your serial ports, 48MHz worked fine for me, while at
50MHz my Mac was not happy and would not boot.
So if you are still interested, you will need a surface mount test clip; 3M and
Pomona make them, and I prefer the 3M ones. Make sure you get a surface mount
test clip. The I.C. test clips also work, but I prefer the surface mount SOIC
(small outline integrated circuit) ones. A 10, 12, 14, 16, or 18 pin clip will
be fine. I'd say go with a 14 or 16 pin narrow or wide clip. I used to recommend
the gold coated ones, but the resistance/corrosion effect is minimal over the
alloy ones. You will also need a 14 pin IC socket, there are plenty of types.
The machined pin ones are nice because you can pop out the pins that are not
needed to get them out of the way since you only need three pins in the socket.
(Yes, just three, pin one on the new oscillator is not going to be used) You
will also need an oscillator (more on this later), a little wire, soldering
iron, solder, and possibly a heat sink and or fan depending on the machine. For
a C610, C660av, Q610, and Q660av you should add a heat sink. And you will want a
fan with the PM's.
The others already have heat sinks, and do not get too hot. I had an extra fan
with my Q800, but removed it, and it has been fine. The heat sinks come with the
clips needed to attach them to the chip. These are a bit of a pain, you just
have to work at it for a while. There may be several ways to do it, but I just
slide the clips on from the side. Sometimes they fall off half way there, but
eventually it works. Some people have been using the heat sink/fan combo's.
The new Q610 and Q660av computers are based on a new mask of the 68040 (There is
an "H" after the '040 and before the "RC") that runs cooler at 25MHz, so it
comes at 25MHz without a heatsink. This is the same mask as the C660av and
Q840av uses. If you do the modification on them it would still be best to add a
heat sink.
How to put it all together:
Stand the clip so it's jaws are facing down, and the rows of pins go from left
to right, and call the closer row A and the further row B. Number the pins from
left to right 1 through 7 (for the 14 pin clip). Next place the 14 pin IC socket
with the pins down, and the notch to the left, and number the pins as 1, 2, 3,
4, 5, 6, 7 in the row closest to you, going left to right. The other row is
numbered 8, 9, 10, 11, 12, 13, 14 as you go right to left (back towards the
notch).
Now starting with the test clip, remove all the pins but four, leaving pins in
positions A2, A6, B2, and B6. Next solder a little jumper wire between pins A2
and A6. Now get the 14 pin IC socket, and remove all the pins but 7, 8, and 14.
Solder a jumper wire from pin 7 on the IC socket to the jumpered pins on the
clip, either A2 or A6 will do. Also solder a jumper wire from pin 8 to pin B6,
and pin 14 to pin B2. If you get the narrow clip, you may want to replace the
spring with one with less tension; they are like $0.30 at hardware stores, and I
cut them into two springs. This way you don't have to push so hard, and it is
easier to position on the motherboard. Now put the crystal in the socket with
pin 1 in 1, 2 in 2, 3 in 3 and 4 in 4.
There are several surface mount oscillators used on the motherboards. The proper
surface mount crystal oscillator on the mother board will have a frequency on it
half that of your computer and can be determined from the previous table.
That is it, now you just clamp it onto the surface mount crystal oscillator with
the notch on the socket facing the same way as the surface mount crystal
oscillator. And watch to make sure the little pins clamp onto the surface mount
chip. You may want to use a flashlight for this. These clips hang on very, very
well, I've never had mine move in the last year and a half, nor any of the other
ones I've done.
Now just turn on your computer and enjoy the speed.
------------------------------------------------------------------------
Centris 610 Ethernet Problems:
Those Centris 610's that have onboard ethernet capability share the 10MHz
oscillator with the CPU. If you replace that oscillator with a different one,
your ethernet will no longer work. In January, Eckart Hasselbrink
(Hasselbrink@fhi-berlin.mpg.de) posted a fairly simple hardware modification to
fix this to comp.sys.mac.hardware. So if you plan to use your ethernet on your
Centris 610 and speed it up, you will need to perform Eckart's C610 Ethernet
Modification first.
------------------------------------------------------------------------
PowerMac's:
I have done several PowerMacs, and their top speeds vary quite a bit. The max I
ever got with a PM6100 was 90MHz, but that was a rare case. At 84MHz the PPC601
overheats quite rapidly. With a cool hairdryer cooling the heatsink on the 601,
it worked fine, but was a bit noisy
. A 12 volt DC 40mm x 40mm brushless fanwill fit snugly inside the heatsink on the PPC601 chip.
Be very careful when you insert the fan into the heatsink on the PPC. If you
press down too hard you may damage the processor itself, and destroy your
computer. Be very gentle; if the fan will not slide in rest the fan on top of
the heatsink, and gently separate the fins of the heatsink to allow the fan to
drop into place.
PM7100(av):
The oscillator you need to grab onto in the PM7100 is located below the
power supply and there is only a small amount of room. You will need to
decapitate the clip prior to wiring it up to get it to fit.
PM8100(av):
You will need a similarly short clip for the PM8100 You will also need to
shave off some of the plastic clip on the computer that holds the
motherboard to the case if you use one of these clips.
Apple's PPC PDS Card
If you have an Apple PPC PDS card installed in one of the above machines
that can be accelerated with these modifications, the card will run at
double the speed of the 68040 processor. The upper limit however is often a
bit lower as the card typically cannot go above approximately 76MHz. See
the above table for exact frequencies. If you accelerate one of these
cards, you should put some extra cooling device(s) on the giant heatsink
unless you use it as a frying pan to cook on. Two fans mounted on extruded
heatsinks and mounted on the card work wonders (no more burns when you pull
out the card).
------------------------------------------------------------------------
Testing the Modification
See the table of machines for information on the typical problems when you are
going too fast. If the problem is with the serial ports, there is little you can
do other than slow down a little. A problem with the serial ports will be
obvious as your computer will hang up or crash when you access your modem or
printer ports. There is a modification to fix the serial port problem on the
C650, and with a little poking around one might be able to come up with
modifications for the other machines to fix these serial port problems.
The video problem on the 660's typically appears as video redraw problems where
the cursor leaves a trace, or the screen does not properly redraw when a window
is closed. James Wang (jwang@soda.berkeley.edu), maintainer of the AV FAQ
(ftp://ftp.csua.berkeley.edu/pub/jwang/av-faq-15.rtf.sit.hqx), recommends
placing small heatsinks on the onboard VRAM to help cool them down as they get
quite warm.
The speed of the memory is also important, so if you plan to boost your Mac very
far, you may need faster SIMM's. It is said that composite SIMMs slow you down
by about 10ns, so if you must get composite SIMMs, get them 10ns faster than you
would have.
To test out the modification, the best thing to do is just use it a while. You
can run Speedometer 4.0 (available via anonymous ftp from cag-www.lcs.mit.edu in
HyperArchive/Archive/cfg) to see the changes. I use Snooper with the serial port
loopback plugs to check the serial ports to find their limits; Snooper also
tells you what frequency you are running at in round numbers. Snooper is no
longer sold, but parts seem to have been incorporated into the latest version of
Norton Utilities, 3.1. The last version of MacCheck, 1.0.5, properly reports the
computer frequency, but Apple has pulled it from all their sites "due to high
support call traffic". TattleTech 2.15 and the updater to TattleTech 2.17 are
now available via anonymous ftp from cag-www.lcs.mit.edu in
HyperArchive/Archive/cfg, and it properly reports the speed of the processor.
If the clip is only half on the computer will not start up. It may be disabling
the surface mount oscillator, but not replacing its signal. If this is the case,
just remove the clip, reposition, and try again.
If the clip missed the surface mount oscillator the computer will start up, but
at its normal frequency. If this is the case, remove the clip, reposition, and
try again.
If the jumper on the clip is broken you will be feeding two frequencies into the
PLL, and it will not be able to lock onto the frequency, and the computer will
not start. To check this, remove the oscillator from the clip, and clip the clip
onto the surface mount oscillator. Try to start the computer; it should not
start. If it does, your jumper wire is broken, or you put the clip on wrong.
If your Mac does not give the standard chime at startup it means your clip is
only half on, or the oscillator is too fast.
------------------------------------------------------------------------
C650 Serial Port Modification:
Using the above clips, the max frequency for a Centris 650 is about 30MHz before
you encounter serial port problems. Marlin Prowell (mbp@janus.com) following up
on a hunch by James McPhail (jmacphai@cue.bc.ca) looked into the differences
between the C650 and Q800 motherboards in hopes that a simple modification might
enable the serial ports to function properly at 33MHz (Q800 normal frequency) or
higher. On the bottom of the motherboard, under the IOSB chip, Marlin found two
differences.
R151 is installed on the C650's, and is missing on the Q800's.
R152 is missing on the C650's, and is installed on the Q800.
R151 is a 300 ohms resistor and R152 is a 1.2k ohm resistor. Looking at the
bottom of the board, with the back away from you, R151 is 3 3/4" from the right,
and 3" down. The tabs for R152 are 4" from the right, and 3" down. R151 is
black, and says 301 on it.
Marlin felt that R151 was glued to the board, and just using solder braid he was
unable to remove the resistor for fear that prying it off may damage the two
traces that run under it. Heating the resistor with a soldering iron Marlin was
eventually able to soften the glue and remove the resistor. Or you can use James
McPhail's two soldering iron Western technique with a soldering iron in each
hand to heat each side simultaneously and flip the resistor off the board. Now
just add the R152. Marlin suggests holding the surface mount resistor in place
with a small screwdriver while soldering it to the exposed pads on the board.
Marlin has since used both the serial and modem ports error free while running
his C650 at 40MHz, and MacCheck reports no problems. He has also checked to make
sure the ethernet works, and it does. Since Marlin's initial modification, it
has been confirmed by at least one hundred people. On some of these Mac's the
CPU overheats after a while, so Marlin suggests you add a fan to dissipate the
heat faster from the heatsink. You can also just run a bit slower, say 38MHz.
You can purchase these 1.2k resistors from Digi-Key, but the minimum order is
200 of them. If you e-mail your US mailing address to Output Enablers at
oenabler@netcom.com, they will send you a free resistor left over from Marlin's
extra 199. OE has obtained some more as over 200 people have performed the
modification with Marlin's spare resistors.
This modification makes your Mac think it has become a Quadra 650, and the
Quadra 650 did not exist when most of you purchased your Centris 650. The System
Enabler 040 that came with your Centris 650, version 1.0, will not work after
this modification, and your Mac will not start up unless you have already
updated the System Enabler 040 to version 1.1, the current version. The System
Enabler 040 version 1.1 is available from your local Apple Dealer, or you can
ftp it from bric-a-brac.apple.com in /dts/mac/sys.soft/7.1.system.enablers.
Marlin suggests you also put the new Enabler on all your recovery utility disks
as well so you will be prepared next time something goes wrong. The System
Enabler is incorporated into System 7.5, so you need not obtain the new Enabler
if you are running System 7.5.
------------------------------------------------------------------------
PowerBook 140 Modification
A few companies have been replacing the crystal oscillator in PowerBooks to
speed them up, and add a 68882 math coprocessor. If you are good with a
soldering iron you might give Glenn Nelson (gwnelson@tddcae99.tddeng00.fnts.com)
and Jerry Cupples' (jcupples@iphase.com) PowerBook 140 Modification a try.
------------------------------------------------------------------------
Duo Clip
If you are interested in speeding up your Duo 210 or 230 without any soldering
on the motherboard you might give Ronald Leenes' (r.e.leenes@bsk.utwente.nl) Duo
Clip a try.
------------------------------------------------------------------------
Address' for some parts suppliers:
Fry's Electronics
340 Portage Ave
Palo Alto, CA
(415) 496-6000
12 volt DC 40mm x 40mm brushless fan
about $10-15
14, 18.432, 19.6608, 25.175, 28.322MHz Oscillators
$2.99
70MHz Oscillator
$6.49
Digi-Key
(800) 344-4539
14 pin IC socket w/tin pins
Part# ED3114
$0.57
3M Surface Mount Test Clip
14pin
Part# 923650-14-ND
$7.83
16pin
Part# 923650-16-ND
$8.28
68040 Heat sinks
0.250
Part# HS159-ND
$3.84
0.350
Part# HS147-ND
$3.94
0.600
Part# HS160-ND
$3.98
Crystal Oscillators
14.31818MHz Oscillator
Part# CTX115-ND
$3.25
14.7456MHz Oscillator
Part# X127-ND
$3.38
16MHz Oscillator
Part# CTX116-ND
$3.25
16.257MHz Oscillator
Part# X128-ND
$3.38
18MHz Oscillator
Part# X117-ND
$3.38
18.432MHz Oscillator
Part# CTX118-ND
$3.25
19.6608MHz Oscillator
Part# CTX124-ND
$3.25
20MHz Oscillator
Part# CTX119-ND
$3.25
24MHz Oscillator
Part# CTX125-ND
$3.25
25MHz Oscillator
Part# CTX126-ND
$3.25
25.175MHz Oscillator
Part# CTX127-ND
$3.25
28.322MHz Oscillator
Part# CTX128-ND
$3.25
30MHz Oscillator
Part# XC316-ND
$4.02
32MHz Oscillator
Part# CTX129-ND
$3.25
32.514MHz Oscillator
Part# X133-ND
$3.38
35MHz Oscillator
Part# X134-ND
$3.38
40MHz Oscillator
Part# CTX120-ND
$3.25
48MHz Oscillator
Part# X135-ND
$3.38
50MHz Oscillator
Part# CTX121-ND
$3.25
50MHz Surface Mount Oscillator
Part# SE2325
$6.53
55MHz CMOS Oscillator
Part# SE1509
$3.60
64MHz Oscillator
Part# X136-ND
$3.88
66.6666MHz Oscillator
Part# CTX137-ND
$4.45
80MHz Oscillator
Part# CTX138-ND
$10.01
Active Electronics
(800) 228-4836
33MHz 68882
Part# MC68882-FN33A
$76.95 plus S&H
Output Enablers
1678 Shattuck Ave. Suite # 247
Berkeley, CA 94709
oenabler@netcom.com
$50-$60/kit
Output Enablers sells kits for the C610, C650, C660av, Q610, Q650, Q660av,
Q800, Q840av, PM6100(av), PM7100(av). They also stock other supplies
including those for the IIsi, Q700, Q900, Q950, PB140, PB160, Duo210,
Duo230, C610 ethernet, and C650 serial port modifications.
------------------------------------------------------------------------
If you have any questions or comments that should be added to this, feel free to
e-mail me.
And a big thanks to everyone who has contributed to this file.
Marc Schrier
schrier@garnet.berkeley.edu
Disclaimer: I have been providing this info for quite some time, and I am now
associated with Output Enablers. I would like to continue to update and maintain
this unbiased information as long as there is interest on the internet. Any
opinions represented here are mine, not necessarily those of Output Enablers.
------------------------------------------------------------------------
Copyright © 1993-4, Marc Schrier
Please contact me prior to distributing or reproducing this file.
tomlee59
Well-known member
It's better simply to link to his site (http://homepage.mac.com/schrier/mhz.html). Saves space, links to the most current information, and also incidentally complies with the author's request not to post his material without prior permission.
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