Classic II/Performa 200 fail

[BadGoldEagle]

It's been recapped fairly well I think. (I checked polarity and everything already). I always clear the gunk in hot soapy water with a toothbrush, after removing the old water towers of course.

This time there was a stain that proved to be quite stubborn as you can see... (around C8 and C9) I've never repaired bad traces before but some look  quite eaten to me. The board appears to be in perfect condition otherwise (i.e. there's no damage elsewhere)



I don't have the trusty 1987 MMU with me at the moment, and I'm going on holiday later today so I won't be able to fix this thing right away but I need your guys opinion. I think the problem lays within this zone.

Oh and here's what happens when I switch it on. 



It chimes like it should, but then 1 second after, it plays the death chime... Adding/removing RAM seems to slow/accelerate the screen garbling effect. It starts with a few lines, then progressively adds more corrupt lines. Some are static, some keep changing. 

That looks to me like corrupt VRAM or UE8 on the SE/30, but what could be causing that on a Classic II logic board?

Any help appreciated.

Thanks!

 

[BadGoldEagle]

After closer inspection (the photo helped a lot, because when you look at it directly it looks a lot less damaged than it is), I think I should run a patch wire across these traces:



But, what type of wire should I use? I have some basic jumper wires laying around but I guess that's not going to cut it...

 

[360alaska]

Get some 28 gauge wire for patch wires. Looking at your board and it's symptoms your problem probably lies in the lower left corner of the board where the 4 ram chips are. You likely need to remove them with hot air and check those traces.

 

[apm]

Wire wrap wire (usually 30AWG) works well for repairing bad traces.

 

[techknight]

meter them before patching them. 

But yep, its definitely a "classic" sign of bad traces. muahaha. I had to... But its true. 

 

[BadGoldEagle]

Got it. Thanks guys. I was suspecting bad ram too but can someone confirm that the traces I was talking about are shot as well?

Techknight, this is a classic "too"...lol

 

[68krazy]

Do I detect a trace of humor in this thread?

 

[techknight]

yep. just a trace. trace is so small a bloodhound barely notices

 

[BadGoldEagle]

I thought there were multiple "traces" on that board.

Spoiler

Get it? Traces as in traces of humour on the 68kmla forum/board and also bad traces on the Classic II logic board... I know, I'm pathetic.

.

 

[techknight]

We both are.... LOL

 

[BadGoldEagle]

Some updates for you guys.

I repaired the damaged trace a week ago. Yes, there was only one bad trace.

It didn't work. Nothing changed.

I took it to bibilit earlier today to double check my repairs and look for possible damage elsewhere. 

Apparently, all traces (at least on the top and bottom layers) are fine now.

BUT here's the catch. Now the display doesn't even come up and it does not chime anymore. The CPU is still getting some power though.

I don't think an internal trace can go that wrong in less than a week. That's why we think a chip might be bad somewhere on that board. Could be the EGRET...

What do you think? 

 

[BadGoldEagle]

Some more updates:

We're back to square one again. Somehow it got "resurrected" but it's still a zombie...

I didn't do a thing since last time... This further proves (I think) that the traces must be fine. Again, I wonder what the experts would say 'cos I certainly ain't one.

NB: Adding or removing RAM doesn't seem to affect it in any way.