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Lisa 2 / Mac XL collapsed deflection or something else?

elemenoh

Well-known member
I've been restoring a rusted out Lisa 2 / Mac XL and just got first signs of life. It's showing a horizontal dashed line. If I remove the memory board, the line becomes less defined. Increasing the brightness makes the line way too bright which makes me think I have a deflection issue.

The PSU has been recapped and both 12v and 5v rails are okay.

The video board has been recapped, but I haven't tried adjusting any of the pots on it yet.

The edge connector on the CPU board is somewhat rough. It is possible not all pins are making a connection.

I completely rebuilt the motherboard, but haven't hunted for broken traces beyond fixing a couple of obvious broken ones.

I haven't checked traces on the CPU board yet.

Where would you recommend focusing troubleshooting assuming this is a deflection issue?

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elemenoh

Well-known member
Turns out I didn't plug in the cable for vertical deflection, doh!

Now I get a beep and some corruption on the screen. I'm guessing this is a bad trace or memory, but if you have advice for where to focus, please let me know.

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elemenoh

Well-known member
@stepletonIt's a single low beep. Per the service manual it looks like it's a problem with memory or CPU. The memory board recap was a little rough, so I'll check the traces on that first.

 

elemenoh

Well-known member
Sure enough, I found a bad connection one of the capacitors I replaced on the memory board. Now I have clean video and a Low - High - Low beeps which indicates an issue with the I/O board. So close!!

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