Apple IIgs Bodge Wires Normal?

[nekonoko]

I have a IIgs that's failing diagnostics with System Bad: 0C000001 error. In addition, it often starts up with strange screeches and displays "unclaimed sound interrupt" when this happens.

My first thought is to socket and change the 4464 sound RAM, but I noticed a lot of bodges including cut traces on the underside of the board around that area. Is this normal? I can't find any photos of the underside of a ROM0/ROM1 board to confirm if these are factory, meant to address an issue or are causing the issue.

 

[joethezombie]

Neither of my ROM1 boards have any rework on the bottom.  The capacitor up by the larger hole, and the other rework pictured are absent.  But I have to say, that's quite professional work.  I would be shocked if it wasn't factory rework.  What board revision?

 

[Lee Adamson]

I've had several ROM1 boards pass through my hands, and none of them have had these mods.  Were it me, I'd probably document the modifications (so as to be able to redo them later if needed), then try to put it back to factory and proceed with repairs from there.

If I get time tonight I might try to dig up a schematic and try to figure out what this mod is supposed to do.  I am curious now.  :3

 

[nekonoko]

I went ahead and temporarily removed the mods and bridged the cut trace, but the system stops with "Fatal system error-> 0911". I also socketed the 4464 sound RAM and replaced with some known good chips, but I still get the System Bad: 0C000001 error and screech during diagnostic (with the mods reinstalled of course).

As for the revision, the board is marked 607-0173-B (B stamped in ink) on the right side of the board near the slots, and 820-0167-B under the solder mask on the front of the board. Thanks much for your assistance in confirming this is unusual - I may wind up looking for a different board.

 

[waynestewart]

I'd have to look for them to be sure but that looks like what I recall seeing on a couple of IIgs.

 

[AichEss]

I have a IIgs that's failing diagnostics with System Bad: 0C000001 error. In addition, it often starts up with strange screeches and displays "unclaimed sound interrupt" when this happens.

My first thought is to socket and change the 4464 sound RAM, but I noticed a lot of bodges including cut traces on the underside of the board around that area. Is this normal? I can't find any photos of the underside of a ROM0/ROM1 board to confirm if these are factory, meant to address an issue or are causing the issue.

View attachment 36694

FWIW I have a ROM1 board that has exactly the same mods and it checks out 100% good with any of the IIGS diagnostics I have. Do you have an Apple Diagnostics 4.x disk to home in a bit on the problem area?

I'm going to guess that the 607-1073-B is the modded revision.

AichEss

 

[nekonoko]

I've only tried the built-in diagnostic so far. I have another IIgs board arriving in the next couple days, once I'm done verifying that one is good to go I'll circle back to the first and see if a diagnostics disk provides a clearer idea.

 

[techknight]

That was done at the factory, and for a reason. I can tell by looking at it. Judging by the R/C filter, they must have had timing issues with one of the lines and they had to fix it. 

Not uncommon to have factory bodged apple hardware, I see it all the time.