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| No video output on Apple Lisa 2/Macintosh XL |
Posted by: Brokoli1 on 2023-04-13 11:11:26
Congratulations! I am surprised but will try to understand better how that mattered. How did you figure it out?
After installing the new Zener diode, I measured again and then noticed that 0V is still displayed. On the other board it was about 0.7V. So I looked for the only difference: The capacitor C3. After unsoldering the capacitor, the values of the diode fit and after installing another capacitor everything worked as it should. I suspect that a lowESR has special characteristics that cause problems in the 5V region. |
Posted by: mactjaap on 2023-04-13 11:14:32
Super! Looking forward to the pictures. |
Posted by: stepleton on 2023-04-13 14:07:07
I suspect that a lowESR has special characteristics that cause problems in the 5V region. Does the capacitor itself still measure well? C3 is not really doing anything too complicated here as far as I can tell. Sorry to keep asking questions --- this is still a mystery to me and I'd like to rule out a defective cap as an answer! |
Posted by: Brokoli1 on 2023-04-14 02:51:59
The C3 measures 10.1uF according to the multimeter, so it's OK. The only difference is now no LowESR....I don't really understand either....
Another question: I am looking for a LisaOS 3.1 in German. Unfortunately I haven't found one yet. I do have a LisaOS 2.0 in German, but unfortunately disk 1 says after booting that the internal hard disk would not be ready and must be rebooted.
I have connected a ProFile with 5MB and was able to cleanly install an English LisaOS 3.1 there.... |
Posted by: Brokoli1 on 2023-04-18 07:55:10
I have now found a working LisaOS 2.0 German version. However, the problem is that this error message appears.
In English: There is a problem with the internal hard disk. It is possible that it was not ready when the disk was started. Click on continue to restart Lisa. If you have further problems, you should consult a technician.
So the ProFile was definitely ready. When I boot LisaOS 3.1 from the floppy, the ProFile is recognized and I can install and use the system without problems. Does anyone have any idea? |
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