Wanted: Advice on performing 68040 upgrade for Q605

[mainland]

I'm finally getting around to swapping the 68LC040 in my Q605 for a full 68040. I have a 68040 donor machine ready to go, put I have no experience pulling chips. Any advice on where I can get the right kind of puller, or on how to do without one? Keep in mind I've never done this before, and I'd be very unhappy if I damaged anything

 

[beachycove]

A broad (1"+) wood chisel can be used to pry the processor out of the socket, working slowly one side at a time. You don't hit it, you turn it like you might a screwdriver, and you keep it out at the edge just under the rim.

I have done several like this with no CPU fatalities. Presumably a knife could be used as well, but a chisel gives good control. (Mind you, I am a woodcarver, so am used to the actions involved.)

After the processor begins to come up, you can basically pull the rest of it up with your fingers. The pins are maybe 1/4" long, so you don't have much to pull.

 

[Bunsen]

Unless you have a proper IC puller, or some other device that can get under and lift both sides at the same time, then the trick is to ease each side up a very small amount at a time, and then go to the other side. That should help prevent you from bending the pins.

I've heard the point of the plastic shirt pocket clip on a Bic biro lid can be good for this. Being plastic rather than metal you run less chance of destroying pins if your hand slips. Otherwise maybe a painter's putty knife?

If you do end up with any bent pins, a retractable pencil is often suggested for straightening them. Remove the lead and use the pencil's lead gripper in the tip to surround the pin and gently bend it back to vertical.

 

[LCGuy]

I usually use a thin screwdriver. I know, not the recommended way of doing it, but as long as you are extremely gentle, you should be fine. I've been doing this for years, and have never had any CPU or board fatalities.

 

[bahkyp]

Just lever the the cpu with a thin knife, SLOWLY. I would suggest no more than 1mm or 1/32" before moving on to next side and repeating, the pins are only 3mm / 1/8". Ok you cant remove it flat but incrementally on a small angle is just fine.

The worst thing I've done with this method is hit the circuit board with the knife and injured one trace. Fixing that with a circuit pen was far harder than straightening a pin. The cpu pins are robust and handle a little straightening.

With insertion make sure they are straight and aligned before putting on any pressure. The cpu should sit down a little when ready to be placed in the socket.

After that you could swap resisitors for a better speed. http://homepage.mac.com/schrier/q605.html The 33 works for me, the 40 never did, even with a resistor from another quadra.

 

[johnklos]

I'm finally getting around to swapping the 68LC040 in my Q605 for a full 68040. I have a 68040 donor machine ready to go, put I have no experience pulling chips. Any advice on where I can get the right kind of puller, or on how to do without one? Keep in mind I've never done this before, and I'd be very unhappy if I damaged anything

Most sockets have little plastic tabs which are meant for a metal clip which holds the heat sink on. Take a broad flat headed screwdriver and use the plastic tabs to pry against and edge each corner up a little at a time. The whole CPU will eventually start coming up after half a dozen rotations or so.

Are you going to up the speed to 33 MHz?

http://homepage.mac.com/schrier/q605.html

You can go up to 40 MHz if you can find a 20 MHz oscillator.

 

[Bunsen]

nb: 40MHz is not always stable though. A heatsink/fan for the 040 would be a good idea.

http://homepage.mac.com/schrier/q605_40.html

Output Enablers sell some useful parts.

even with a resistor from another quadra.

That would make no difference whatsoever.

 

[mainland]

We'll see how the CPU swap goes before I decide on overclocking. I actually have a Q605 and an LC475 as well as two 68040 donor machines, so I have some room for error. My end goal is to have a Q605 with a full 68040, possibly overclocked, 128Mb RAM, and a new HD (whenever I can scrounge up an IDE-SCSI or (preferably) SATA-SCSI bridge). This machine will host my Apple IIe card, and dual boot 7.5.5 and 8.1.

 

[Quadraman]

Don't try to pry one side out completely before the others. You'll bend some pins. You need to work around the CPU and try to pry all sides up a little at a time until it comes loose. Your risk of bending pins is greatly reduced. I have a full 040 in my Performa 631CD and it makes a difference. I wish I was brave enough to change the clock resistor on the motherboard to get it up to 40mhz.

 

[ojfd]

nb: 40MHz is not always stable though. A heatsink/fan for the 040 would be a good idea.

I can confirm it - at 40 MHz heatsink is a must and you should use at least 33MHz processor if overclocking that baby!

My Q605 had processor socket with notches which permitted fitting a heatsink from Q650/700 variety. I also installed real 40 MHz 68040 and changed Motorola PLL chip. After these mods machine have been stable for something like 8 years or so.

ojfd

 

[johnklos]

If you can't find a socket with clips, you can get something like Arctic Silver thermal adhesive:

http://www.newegg.com/Product/Product.aspx?Item=N82E16835100005&cm_re=arctic_silver_thermal_adhesive-_-35-100-005-_-Product

(not specifically endorsing Newegg, but they are a pretty no-fuss company)

I've used this to adhere the heat sinks on a number of QuadDoubler-type CPU cards. You can see a little bit between the CPU and the heat sink in this picture:

Just FYI - almost all m68040s in Quadras were made with the exact same mask and feature size, so there's no manufacturing difference between most 25 MHz m68040s and 40 MHz m68040s besides the fact that the 40 MHz parts were tested at 40 MHz in the factory. I've overclocked many 25 MHz CPUs to 40 MHz without problems, and I wouldn't be surprised if they worked fine at 50 MHz in QuadDoubler-type situations.

What'd be nice would be to find a source of Freescale post-2002 m68040s which are made with a smaller feature size, take much less power, and can probably run much faster. The latest (and perhaps last) mask from Freescale is L88M at .57 microns.

I imagine one in a QuadDoubler-type card on a 33 MHz motherboard would be sweet. It might even be possible to run such a CPU at 80 MHz... One of these days I'll find one!

 

[trag]

nb: 40MHz is not always stable though. A heatsink/fan for the 040 would be a good idea.

I can confirm it - at 40 MHz heatsink is a must and you should use at least 33MHz processor if overclocking that baby!
My Q605 had processor socket with notches which permitted fitting a heatsink from Q650/700 variety. I also installed real 40 MHz 68040 and changed Motorola PLL chip. After these mods machine have been stable for something like 8 years or so.

Did you do the 40 MHz modification on a Q605? If so, did you use one of the two methods listed on Marc Schrier's page with wires and such, or did you just do the resistor swap for 40 MHz?

 

[ojfd]

Hi trag,

Yes, I've modified Q605, not LC475, althoug I've put a jumper on the MB after I went to 40 MHz, which changed its gestalt ID to LC475.

At first I swapped resistors to go to 33MHz and afterwards I installed 40MHz oscillator, as per instructions on Marc Schrier's page.

http://homepage.mac.com/schrier/q605_40.html

I also changed MC88920 PLL to MC88916DW70 which I removed from that useless IIvx MB, installed "real' 40MHz MC68040 and put a heatsink on it. Heatsink came from Q700 that had damaged video output.

Cheers,

ojfd

 

[Quadraman]

Would you still need a heat sink/fan if you were using an 040 that was actually rated for 40mhz? I have two of them installed in 33mhz machines that I want to kick up.

 

[trag]

At first I swapped resistors to go to 33MHz and afterwards I installed 40MHz oscillator, as per instructions on Marc Schrier's page.
http://homepage.mac.com/schrier/q605_40.html'>http://homepage.mac.com/schrier/q605_40.html

I also changed MC88920 PLL to MC88916DW70 which I removed from that useless IIvx MB, installed "real' 40MHz MC68040 and put a heatsink on it. Heatsink came from Q700 that had damaged video output.

Thanks. I did the MC88920/88916 swap, and pull pin 9 high (?) or something like that.

http://homepage.mac.com/schrier/q605_40.html

on one machine but could never get video. But I think my VRAM is too slow. There's a note about sometimes needing 80ns VRAM after the 40 MHz upgrade. I've set it aside for several months though (hmmm, I guess it's been almost two years actually. Sigh).

But I've always wondered why the straight resistor swap won't do the trick. Schrier's page says it doesn't work, but it also doesn't say that anyone ever tried it with the clock generator/buffer swap. It seems to bear more experimentation. One of these days...

Hmmm. I just looked over the 88916DW70/80 datasheet and reread the speedup instructions. I wonder if I pulled pin 9 of U17 high, or if I pulled pin 9 of the DW88916 high? I can't remember now, but I think I may have gotten confused and done the latter....

 

[johnklos]

Would you still need a heat sink/fan if you were using an 040 that was actually rated for 40mhz?

Yes. The 40 MHz part is made exactly the same as the 25 MHz part, so you'd definitely need a heatsink at minimum. On the other hand, if you can get your hands on a Freescale made m68040, they will run almost cool at 40 MHz without a heatsink.

 

[johnklos]

Thanks. I did the MC88920/88916 swap, and pull pin 9 high (?) or something like that.http://homepage.mac.com/schrier/q605_40.html

on one machine but could never get video. But I think my VRAM is too slow. There's a note about sometimes needing 80ns VRAM after the 40 MHz upgrade. I've set it aside for several months though (hmmm, I guess it's been almost two years actually. Sigh).

But I've always wondered why the straight resistor swap won't do the trick. Schrier's page says it doesn't work, but it also doesn't say that anyone ever tried it with the clock generator/buffer swap. It seems to bear more experimentation. One of these days...

I'd be interested to hear the results.

There's another simpler way to get to 40 MHz which used to be available from here:

http://gabezing.sytes.net/LC475-40Mhz-E.html

However, that site's been unavailable for a while and archive.org doesn't have copies. Does anyone have a copy or know of a mirror? We need to put those up.

The process is simpler than sourcing a MC88916, and simpler installing, too. Just get a 20 MHz oscillator, take the power for it from the 31.3344 MHz oscillator on the corner of the motherboard by the video connector, remove R93 from the backside (also close to the video connector), and run the 20 MHz oscillator's output to the inside pad where R93 used to be (by inside I mean towards the center).

I've done this mod on a number of motherboards, and it's never not worked at 40 MHz.

Here's one of the machines to which I did this modification something around ten years ago:

http://www.mac68k.org/~john/boobookitty/

 

[Quadraman]

On the other hand, if you can get your hands on a Freescale made m68040

Yeah, like that's gonna happen. They are like $250-$300 each in bulk according to Freescales' site. 8-o

 

[johnklos]

You never know - companies are still buying them, so it's just a matter of time before some older product becomes "obsolete" and the chips work their way onto eBay. Or if a company goes titsup, their stock could get liquidated. I'm hoping...