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Apple Lisa doesn't boot - need help troubleshooting

Juror22

Well-known member
From the 'Lisa Troubleshooting Guide' Rev. Apr 84, Page 6.l2

SYMPTOM
Incorrect or no video, no "clicks", and no error tones.
 
PROBABLE FAILURE
- CPU
- I/O
- (Go to Video Repair Procedures)
- Motherboard
 
The troubleshooting method that they describe is to swap in working ones, to determine the bad card.  If someone has a different way to go about this, let me know.  Otherwise, I think I might just button them up and set them aside until I can get a working one to swap parts and determine which card is the issue.
 

all2coolnick

New member
I have a very similar problem. I have two Lisas; one fully working and another that one of the main safety caps in the PSU had blown. They are both the Datapower 180W PSUs. I've replaced all 5 of the yellow boxy safety caps and the two huge round caps. 

I normally run power supplies through a 100W light bulb when testing to avoid nasty explosion (Jestine Yong tip) but this is preventing the Lisa from starting up. Whether I use the original PSU or the repaired PSU in the fully working Lisa, the power button light blinks on, status builds up on the screen, the 100W lamp pulses on momentarily (that's normal as the main input caps charge up) and then the Lisa powers off.

As the symptoms were identical for both PSUs, I was hopeful I had repaired the faulty one OK.

However, when I connect to the mains without going through the 100W bulb, the Lisa starts up fine with its original PSU but when I try with the repaired PSU, it trips the circuit breaker in my house.

I'm not quite sure how to proceed. I've read the above tips on how to set up the PSU to test on the bench but how do I test it if it trips the mains? My normal trick would be to use the 100W bulb but this seems to be preventing the power supply from starting up even though it is also preventing the mains from tripping.

Any suggestions would be appreciated.

Thanks

 

elemenoh

Well-known member
@Juror22Did you ever get your Lisa working? I'm having the same problem. The Lisa powers on when plugged in. I get I/O Error 52 (COPS error). I checked all the traces for the first connections from each pin of COPS and cleaned the chip and socket with contact cleaner, but the issue persists. I'm seeing the CK0 pin show a blip at 3.9MHz when power is first applied but then it goes flat. Is that signal supposed to persist? I didn't get discernible signals from any of the other pins, but I'm not sure what I should be looking for.

Are there some basic signals to check for on the COPS chip to determine if it's functioning correctly?

 

Juror22

Well-known member
Sorry, but I did not.  I ended up selling my Lisa to someone that thought they could get it running.  I wish you good luck and I hope that you are able to get yours running.

 

elemenoh

Well-known member
I figured it out on my board. A trace (poorly highlighted below) from a via just below D9 that ran below the battery was broken on the top side. I bodged it on the back side and standby/soft power started working normally. Now I get a memory error 70 during the startup test. Psyched to have made progress though. 

7392F09B-F145-49A2-BD62-83899BB72BFD.jpeg

 
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