Sad SE/30 video error and no sound

ComputerCompulsive

ComputerCompulsive

Tinkerer
Nov 27, 2022
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Hey folks!
I picked up a 40 dollar SE/30 that needs a little TLC. It was completely dead but after recapping I get part of a video signal. Seems like some lines are corrupted.

I found one bad trace going to ue8 and repaired it and now the video looks like this (see photo)
1000001204.jpg
it's improving but for the life of me I can't find any more bad traces in that area. I toned out everything along ug8 to ua9 and still no bad traces.

Tried swapping out the socketed chips too from a dead board but again no difference. Any recommendations where to check next please?
 
ComputerCompulsive

ComputerCompulsive

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Nov 27, 2022
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I have made progress!
Thanks to CayMacVintage who provided me with a matrix of address paths I was able to find a bad trace between UD8 and UI8 and another on UE8 which has taken me from video to clear video. Only issue now is the sound. I've been toning out the paths from sound chip and so far everything single one has checked out. Have a half dozen more to check and then I'm going to be stumped. Is there anything anyone else can suggest for checking regarding the sound?

Thanks

1708376160726.png
 
ComputerCompulsive

ComputerCompulsive

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Nov 27, 2022
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croissantking said:
No sound is a symptom of bad caps.

Get that puppy recapped.
Click to expand...
Caps are all replaced. System was completely dead before I replaced the caps. Still testing traces hope I find another break to repair otherwise I'll try jumping pin 2 and 4 on the audio jack see if the jack is stuck.

Last resort I'll start pulling off chips cleaning and replacing.
 
ComputerCompulsive

ComputerCompulsive

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Nov 27, 2022
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Went through the matrix and checked every line to the sound chip but no breaks that I could find. I took the sound chip off, cleaned it, and put it back on and now I'm getting a chirping/squealing noise at start up. I can hear it on the speaker and if I plug in the headphones I can hear it there so I have to assume the jack isn't stuck. All the caps appear to be on in the correct places and in the right orientation so I'm back to being stumped. Any suggestions please?
 
se30

se30

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Mar 9, 2024
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If you haven't already you might consider getting the board a good thorough wash.

I have a Mac SE 30 as well and I can give you pin ohm and voltage readings on the sound chip if you feel that may help.
 
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y0ssar1an

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Feb 11, 2024
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se30 said:
If you haven't already you might consider getting the board a good thorough wash.

I have a Mac SE 30 as well and I can give you pin ohm and voltage readings on the sound chip if you feel that may help.
Click to expand...

I'm also happy to take readings from a working board, if you want more than one datapoint.


Is that pin matrix published online somewhere? I have similar-ish problem I'm looking to diagnose.
 
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Kai Robinson

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ComputerCompulsive

ComputerCompulsive

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Nov 27, 2022
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This Does Not Compute said:
There's also the SE/30 schematic redraw project, which includes two pages at the end that are *very* helpful for diagnosing connection issues:

github.com

macse30mlb/hardware/pcb/mlb/output at master · mishimasensei/macse30mlb

Macintosh SE/30 Main Logic Board Schematic Drawings - mishimasensei/macse30mlb
github.com github.com
Click to expand...
Yes CayMac showed me this one and I originally used it to diagnose and fix the video issue. I've gone through it for the audio section as well and nothing appears to be broken. I'll do another pass on it now that I've removed, cleaned, and reattached the sound chip to make sure nothing is missing after that.

I just received an ultrasonic cleaner but no one locally is selling the electronics cleaning solution and I really don't feel like paying the nearly the same amount for cleaner solution to have it shipped as I payed for the actual device ($400 Canadian). I might give it a try with distilled water and dish soap per Branchus Creations suggestion and the dip it in some Rubbing Alcohol afterwards.

If that doesn't work my wife bought me a oscilloscope last Christmas I guess now is as good a time as any to learn how to use it. Though I'll likely be back to ask for help with that since I'm new to it.
 
ComputerCompulsive

ComputerCompulsive

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Nov 27, 2022
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se30 said:
If you haven't already you might consider getting the board a good thorough wash.

I have a Mac SE 30 as well and I can give you pin ohm and voltage readings on the sound chip if you feel that may help.
Click to expand...
Will try that next and then go through the cheat sheet again to make sure everything is still connected after the removal and cleaning of the sound chip.
 
ComputerCompulsive

ComputerCompulsive

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Nov 27, 2022
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Ultrasonic Cleaning didn't change anything. So I decided to take off the sound chip again and put it back on (from a different logic board known to have sound). Now I get this... But only when hitting interrupt/reset


Any ideas please?
 
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