Back to the Lisa...

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Last seen: 3 weeks 3 days ago
Joined: Jan 19 2014 - 15:25
Posts: 61
Back to the Lisa...

Hi everyone,
Since I'm home for the holidays, I thought I'd get back into trying to fix up my broken Lisa 2/10. First of all, the most pressing issue is that the CPU board seems to not be working. I've posted about this one before, but I've got some more reliable testing and information available this time that *hopefully* should narrow down the problem.

(I'm testing the broken CPU board from the 2/10 in my working 2/5, to eliminate any other problems the 2/10 has from the equation)

All socketed chips from the board have been tested with the working machine separately, one at a time, and they all work.
The board has the expected "H" ROMs for a Lisa 2/10.
Additionally, the legs of all these chips have been cleaned, as has the large gold edge connector.
Luckily, coming from a 2/10, corrosion is not an issue with this board (never thought I'd be saying THAT about a Lisa), and no corrosion is present.

When I have my good 2/5 with this board installed, I am able to still power on the unit using the soft-switch power button on the front. On the default brightness setting, nothing comes up on the screen, and the speaker does nothing as well (no clicks or anything). However, if I turn up the brightness, I get a simple, gray display, as shown here:

At this point, I am not able to power down the Lisa using the power switch on the front. If I press the reset button on the back of the machine, the faint lines shown in the picture attached above "jump up" a bit, before settling back into their original place about a second after I release the button.

In the past, I have tried the "cut the capacitor leg" trick (the one by the processor that deals with the reset circuit), to no avail.

Here's a picture of the board itself:

If anyone knows anything I can test here to further the process along, please let me know. As always, I can supply more pictures/video of something upon request, so feel free to ask if that makes the diagnostic process easier.

Merry Christmas and happy holidays everyone!