General Category > Lisa Troubleshooting and Repair

Diagnosing no power

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paule:
I have a Lisa that doesn't power up.

Lisa Troubleshooting Guide (Level I Lisa Technical Procedures) spells out these steps:
    ...
    4. Verify secure connection of ribbon cable from motherboard to softswitch/keyboard assembly.
    ...
    7. Swap out the modules in the following order:
      a) power supply
      b) I/O board
      c) softswitch/keyboard assembly
      d) front interlock switch
      e) disk drive to card cage connector
      f) motherboard
      g) videoboard

I swapped out the power supply with a known working one without change.

Do the softswitch and interlocks need to be swapped out to be tested or are there shortcuts folks have discovered? (I can do it with parts from another working Lisa, but it seems like a fair amount of work to largely disassemble and reassemble two Lisas to test each part.)

Any other tips before I proceed?

blusnowkitty:
I'd start here by pushing in the interlock switches and measuring for +5vsb on the COP421. Correct me if I'm wrong, don't the interlock switches kill even standby power if they're not set?

fri0701:
I had a problem like this recently, and it turned out that one of the connectors that connects to the card cage when pushed into the back of the case was corroded and damaged. You might want to check that if your Lisa has battery damage (but beware - the pins are very delicate).

compu_85:
Do you have a 2/5 or a 2/10?

Note that the COP won't turn the system on if it thinks it's already on. On my 2/5, battery leak damage had corroded the pin going to the COP which told the system it was on. If I forced the system to come on it would work, repairing that trace made it work normally.

-J

paule:
I should have specified 2/10, so no battery damage per se. Could be that some other kind of corrosion has happened.

How did you "first the system to come on"?

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