General Category > Lisa Troubleshooting and Repair
Edge Connector for the IO Board
sigma7:
--- Quote from: pintoguy on April 25, 2022, 12:34:02 pm ---mmm, I spoke too soon. The problem seems more complicated than I thought.
--- End quote ---
U1 - 74LS132 on the motherboard is in the signal path for built-in video, so look around there, swap it out, suspect the socket, etc.
The video signals aren't associated with the I/O connector you worked on, and all of those discrete components in the area of Q1 & Q2 are for the external video only.
pintoguy:
--- Quote from: blusnowkitty on April 25, 2022, 01:39:20 pm ---Have you tried twiddling the knobs on the affected Lisa's analog board? I know when I was trying to get my 2/5 up and running on its original battery damaged I/O board, the video signal was so overdriven the screen was mostly white with black smears here and there.
You could also have a broken component on your analog board. Mine apparently had been used so much that a plastic insulating tube on one of the coils broke apart. Fortunately there wasn't any electrical damage.
--- End quote ---
Is Analog board = Video board ? If it is, then yes, I fiddled with all the trimpots with no success. And I did put a spare, working video board in the 2-5, again a no-go
--- Quote from: patrick on April 25, 2022, 01:51:31 pm ---This will work as long as you do not connect any floppy or hard drives. The power harness is almost the same for the 2/5 and 2/10, but the drive harness is different.
--- End quote ---
OK thanks. The floppy drive needs work anyway, so I'll remove the drive cage and try.
--- Quote from: sigma7 on April 25, 2022, 03:04:24 pm ---U1 - 74LS132 on the motherboard is in the signal path for built-in video, so look around there, swap it out, suspect the socket, etc.
--- End quote ---
Great, thanks. I'll check
By the way, the video contrast latch circuitry is on the IO board. Could a faulty latch make the screen blank ?
pintoguy:
Success !! I had both Hsync and Vsync traces corroded away, right near the connector J5 on the MoBo. They are actually very narrow there, and it doesn't take much oxidation to eat the copper up completely.
Now on to the floppy drive (all seized up) and the keyboard (foam pads need replacement).
Thanks, as always, to all the good people on this board or on 68kmla where I used to post. You guys are the best !
(Edit): Am I the only one having trouble with file attachment ? I've been trying all day. Sometimes I get the error message: "Your attachment has failed security checks and cannot be uploaded. Please consult the forum administrator". Sometimes it looks like it's working, but it is actually not uploading the pics.
compu_85:
I've had some luck swapping individual pins on I/O board connectors. After desoldering and removing the subs, be sure all the old solder is removed. Then a new pin can be slipped in from the top.
This assumes there's no board damage / other grunge under the edge connector. If it looks green under the plastic, best bet is to remove the whole thing and clean under it.
-J
pintoguy:
Good to know. Thanks
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