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[pintoguy]

Just posted this on 68kmla. If anyone can help, that would be fantastic. Thanks !

https://68kmla.org/bb/index.php?threads/lisa-video-board.49827/

[AlexTheCat123]

I know you said you've already tried messing with the pots, but have you replaced any of them? In my experience, a bouncy screen like this is often caused by a flaky pot, and replacing it fixes everything right up. I'd focus on the HEIGHT one first, but it's probably a good idea to just replace them all because replacements are cheap and the originals are just so unreliable all these years later.

[pintoguy]

Thanks @AlexTheCat123. I desoldered the Vlin pot but it measures perfectly. I did not check the other ones but they all seem to respond normally to tuning. Plus the video is actually no longer jumpy.

I saw somewhere that you have experienced issues with the vertical deflection controller TDA1170N, and replaced a few. Did you ever see any of these symptoms ? And is it a difficult/tricky job to do ?

[pintoguy]

Progress ! I usually don't check resistors that do not look burnt, but becoming desperate, I did. One of the resistors feeding TDA1170 (R28) showed 470 kOhms when it should be only 56k. After a quick swap, I get a much better image (below). R28 is actually next to C18 on the board, and it's possible that it got a bit too hot when I soldered C18, leading to failure.

The image is still squashed a bit, clearly exhibiting a vertical linearity issue. I'm surprised to see a second problem, but I'm not complaining 

[pintoguy]

Never mind, I traced a short that I made on the board while reflowing the contacts. Looks like I've got everything under control now. So in the end, it was resistor R28 that got fried in the process of recapping C18. It's only my second resistor problem in my 10+ years of Mac and Lisa tinkering !

[ried]

What I/O board ROM version is 9F (H/9F in your pic)? Don't think I've come across that one before...

Edit: I wonder if that has something to do with your I/O board error during POST.

Edit 2: I/O board error 57 seems to be related to the disk controller and / or your Lisa Lite adapter board in a 2/5, per https://lisafaq.sunder.net/lisafaq-hw-rom_error_codes.html

[pintoguy]

This is a problem from a Lisa 2/5 that dates back from 2023, that I had never solved, and that I put on the backburner for a while. See here

https://lisalist2.com/index.php/topic,423.0.html

The video board is actually from a different system (a 2/10), and I use the "bad" system as my work horse. Now that the video board works, I'll get back to working on my 2/5.