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Topic |
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fun_in_a_box
Starting Member
Australia
3 Posts |
 Posted - 18 Oct 2002 : 13:13:06
Hello!First time posters, long time lurkers. We have a non-booting Classic II we picked up recently. It has a logic board that (to us) appears altogether quite strange. There is a thin blue wire running between the Eagle VLSI chip and the Egret. We can't find a pic of a Classic II logic board *anywhere* to see if this is an authentic "Apple-approved" wire or the work of some madman <grin>. There is also a 10,000 ohm resistor (we think we read it correctly) that is soldered between a resistor(?) and a pin on one of the ROM chips (on the underside of the board). We have searched *everywhere* we can think of for information about either, and are about to snip one or the other (flips coin) to see if this will make the d4mn thing boot. The machine sometimes:
(i) does nothing at all
(ii) powers the monitor (vertical lines, alternating black then white)
(iii) powers the monitor (grey screen then the 'sad mac' chimes - no mac icon) We threw in a Classic logic board and the machine booted fine. Of course the service source/manuals *all* say that if the classic II displays any of these problems then there is no solution other than complete replacement of everything. Any suggestions/solutions would be greatly welcomed. Edited by - fun_in_a_box on 18 Oct 2002 13:17:57 |
cinemafia
Guerrilla Recon Leader
USA
2965 Posts |
Posted - 18 Oct 2002 : 13:19:51
Have you tried bathing the mobo?No, but seriously, I have no idea...I've been inside almost every compact but a Classic/Classic II. 666th poster and 666th thread-creator
Mod of the Mac II series Forums
Total 68K Macs liberated: 7
My Site: http://cine.sytes.net
My Hotline Server: 840av.sytes.net
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jruschme
Junior Member
USA
196 Posts |
Posted - 18 Oct 2002 : 13:41:02
quote:
We have a non-booting Classic II we picked up recently. It has a logic board that (to us) appears altogether quite strange.There is a thin blue wire running between the Eagle VLSI chip and the Egret. We can't find a pic of a Classic II logic board *anywhere* to see if this is an authentic "Apple-approved" wire or the work of some madman <grin>. There is also a 10,000 ohm resistor (we think we read it correctly) that is soldered between a resistor(?) and a pin on one of the ROM chips (on the underside of the board).
It sounds like an engineering modification. Any indication that you have some kind of pre-production model?
<<<john>>>
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Marchie
Chaplain
USA
911 Posts |
Posted - 18 Oct 2002 : 14:53:08
What are the part numbers on the boards?How good is the solder job? what pins does the wire connect? ~Marchie ~Chaplain Marchie
Admin of The WonderLAN
~~"We are all Mad here"~~ |
fun_in_a_box
Starting Member
Australia
3 Posts |
Posted - 18 Oct 2002 : 16:34:05
kind of doubt it is a pre-production model (unlikely to turn up in Sydney) - of course we would do a little dance** of glee if proved wrongthe quality of soldering is quite good - however the blue wire is held down to the board in various spots with largish untidy globs of ... stuff (glue? silicon?) Not having seen a Classic II board, we weren't sure if this was "normal" or not (just doesn't look typically mac-ish to us - everything is normally so pristine) THANKS SO MUCH DANA! its *not* normal :) a very bad quality jpeg of the route of the mystery wire is at http://funinabox.marhost.com/picks/classic_ii_wire.jpg a rather bodgy diagram showing where the wire joins the egret chip is at
http://funinabox.marhost.com/picks/egret.jpg Our current favourite theory is that some *genius* has decided to do *something* of his own design to it, which didn't quite work and rather than reversing the mistake - put it in a cupboard/garage/shed and forgot about it. preparing to do comparison with scans
fib
_______________________
**and then some!
its gotta be worth thousands ... the case has all these signatures in it!! |
ehurtley
New Member
USA
63 Posts |
Posted - 18 Oct 2002 : 18:38:23
quote:
kind of doubt it is a pre-production model (unlikely to turn up in Sydney) - of course we would do a little dance** of glee if proved wrong
You'd be surprised where pre-production models turn up... Okay, I used to work for Intel's server motherboard division, and we used little blue wires all the time to correct engineering or manufacturing bugs. And yes, they went out to customers that way sometimes. It might be a warranty return, something that broke, and he easiest way to fix it at the time was to blue-wire it. Lots of times, that was cheaper than sending out a new board. Heck, at Intel, when a new revision of the Pentium III processor came out, we blue-wired ALL new boards coming out of the factory for about 2 months because an incompatibility was discovered, and it was the only way to make the boards compatible with the new processor until a new revision of the motherboard could be developed (took about a month, plus another month to 'validate'.) I've had 'blue-wire' products from other manufacturer's too. And I vaguely remember seeing a blue-wire job on a Mac once upon a time. I think it was a PowerMac, but I don't remember for sure. Why computer companies always use blue wire, I don't know. They just do. Proud Liberator of over 25 Macintoshes! |
Trash80toG-4
NIGHT STALKER
USA
2899 Posts |
Posted - 18 Oct 2002 : 19:39:36
quote:
Why computer companies always use blue wire, I don't know. They just do.
I was wondering the same thing, I think all the factory patch wires I've seen have been blue, it must be color coding for a factory done patch. It probably means early production, not necessarily pre- production, or it could just be a mid production fix on a board that had one faulty or accidentally damaged trace.jt  ™.
Trash Hauler: call sign: eight-ball
C.O. AC-130H SpecOps 68kMLAAF |
fun_in_a_box
Starting Member
Australia
3 Posts |
Posted - 18 Oct 2002 : 23:07:16
Well, we’ve compared and contrasted with some interesting results ... Differences: Our silk-screened mobo part number is 820-0401-A
(Dana's is 820-0401-B)
The part number on our barcode is 630-0401-S7
(Dana's is 630-0401-B) The blue wire of evil (b.w.o.e.) is connected to the tiny tiny hole above slightly at the top right of U18 (appears to connect via the pcb to pin 49 of the eagle chip) - on Dana's scan the "hole" appears to be filled with solder The b.w.o.e. connects to the egret chip on pin 6 (the "x") at the other end |||||X||||||||
--------------
| egret chip |
--------------
|||||||||||||| Unsure if the little black letters and numbers stamped at random over the board have any relevance (we have more - and they are different, but for brevity's sake we'll leave them out. The back is interesting...
on the underside of the ROM chip marked 341-0867 we are missing "R96", even more interestingly this is where our mystery resistor is located (soldered from the "x" pin to C109). (spooty forum code) sad ascii type diagram removed...
but an image of it can be found at
http://funinabox.marhost.com/picks/rom-undersides.jpg
We spent last weekend reading the delightful hardware developer note, but sadly were none the wiser on what that *bit* of the Eagle chip might be for.
We also read the Service Manual - which blamed alternately: the power supply, the crt, the logic board (as they do) - we've narrowed it down to the logic board (we think).
Could be time to start snipping a certain "little blue wire" (although the bathing is looking like a mighty fine idea). Thanks muchly for all of your assistance / comments. fib (we have a very elderly trs-80 which is crawling with blue wires - it doesn't work either ... blue wires of death?)
its gotta be worth thousands ... the case has all these signatures in it!!
Edited by - fun_in_a_box on 18 Oct 2002 23:26:48
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~Coxy
Leader, Tactical Ops Unit
Australia
2822 Posts |
Posted - 19 Oct 2002 : 06:13:27
Heh, blue wires of death.
And interesting factoid for you:
Every single MCA board I've seen has at least 2 or 3 blue wires running across it.  ~Coxy - Leader, Tactical Operations Unit
Mayor of NuBus City v3.0
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Trash80toG-4
NIGHT STALKER
USA
2899 Posts |
Posted - 19 Oct 2002 : 07:00:40
quote:
Heh, blue wires of death.
And interesting factoid for you:
Every single MCA board I've seen has at least 2 or 3 blue wires running across it.
HAR! MicroChannel cards never made it past early production!The only one I have is a NuVista I bought to snag the VRAM, I'll check it for blue wires, I don't think it actually made it that far in testing tho, I don't think it was ever completed, looks like a reject. yo, maniac! thanks for the linkage, I'd never seen that red-wire definition in the lexicon before, ROTFLMFAO! jt ™.
Trash Hauler: call sign: eight-ball
C.O. AC-130H SpecOps 68kMLAAF |
Trash80toG-4
NIGHT STALKER
USA
2899 Posts |
Posted - 19 Oct 2002 : 07:15:48
quote:
. . . its gotta be worth thousands ... the case has all these signatures in it!!
LOL! good one!The forum munges any ASCII art that you don't use lighted candles, incense and the </code> tag incantations to protect from its evil spells. The blue wire of death sounds like a fix for a broken trace to me, when you clip it, test the continuity of the trace between the via and the pin. I'll bet it's flakey or nonexistent in terms of connection and that it is fine on the maniac's machine. Being that far apart and at right angles, there will probably be another pair of vias and short traces between the two solder points with a fault or an intentionally cut incorrect trace connection that's fixed by that blue wire patch.  jt ™.
Trash Hauler: call sign: eight-ball
C.O. AC-130H SpecOps 68kMLAAF |
Marchie
Chaplain
USA
911 Posts |
Posted - 19 Oct 2002 : 10:37:34
Wires running across the mobo and glued down is quite common in the older Macs... most specifically the compact Macs.In pre-SuperDrive SE's there is ALWAYS a wire like that wired across the board. Remember that these boards were half constructed by people, and only half by macheine. 1 out of 3 SE/30's I've laid eyes on has a very weird wire connecting the logic board to the analog board... quite small, glued down, and confuseing as anything, since it makes taking it apart and upgradeing a REAL riot,let me tell you. I'm opening my CII in the next 2 days to swap the hard drive.. I'll check part numbers, and see about taking pics. Anything we find out about this needs to go up on the website! ~Marchie ~Chaplain Marchie
Admin of The WonderLAN
~~"We are all Mad here"~~ |
Classic II logic board: the strange blue wire etc
68k of the Week: kastegir's PowerBook 180.