Apple Lisa troubleshooting

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Joined: Nov 21 2005
Posts: 1

For those Lisa enthusiasts; I recently acquired a wokring LISA, (actually an unmodified MAC XL) ROM indicates H/88. I am in the process of attempting to acquire LISA OS and loading that, anyone who has done such please feel free to comment/advise. But my question today is related to video and/or power supply., I am observing the following and would appreciate any comments: The machine appears to work fine, but I ahve noticed this one interested characteristic. The screen is bright, stable and clear, but when you open/change folders or applications, the screen dims significantly during the transition, then brightens up again - almost like it is designed to do that. This occurs without accessing the hard drive, sot the only "power" transient would be the RAM cards. Any thoughts on what might be going on here? thanks in advance, mike

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Joined: Jan 23 2005
Posts: 595
I had an old PowerBook that did that...

I had an old PowerBook 150 that did that. When you opened a folder, the screen would dim or get brighter. It was really quite weird and most annoying. I would hazard to guess that this is not a design feature.

If I were to take a wild guess, I'd say that there is probably a flaky capacitor or two on the logic board, analog board, or whatever is inside the machine you have. Check for failing or failed capacitors.