Re: Help with dead lisa 2 getting closer!

Hi Vince,

>I get 5V off of U7F pin 14 but crossing 14 and 12 didn't power up unit.
>I've checked to make sure the motherboard connections are clean.

Check U7F-12 goes to pin 120 of the edge connector, if so, then I would again suspect the power supply. Bringing that pin to 5V should turn on the power supply.

>Well, that wasn't it but, I've found resistor pack 3 RP3 missing, 99% broken
>off. Does any body know the size of the pack and would this cause the
>problem?

On my Lisa 2 (not 2/10) I/O board, it looks like a custom job...

Pin 1 to Pin x:

    2 10k
    3 20k
    4 40k
    5 80k
    6 160k
    7 320k
    8 short

This is used for the display contrast control. Seems unlikely to cause the problem...

I would look for further damage... for example, does your I/O board have a flying wire from U7F-12 to the cathode of D4?

And, as Randy said, check very carefully for corrosion around and under the battery pack.

Good luck!

James

James MacPhail                   "Think not of engineering as art,
uo957_at_email.domain.hidden                 but of art as engineering"
Sigma Seven Systems Ltd.
james_at_email.domain.hidden        <http://SigmaSevenSystems.com>

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