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Lisa 2 / Mac XL collapsed deflection or something else?


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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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Edited by elemenoh
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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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11 hours ago, elemenoh said:

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!!

 

That's big progress.  Nicely done.

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