Bwana_fr

Missing capacitors is normal, I remove them to check some PCB tracks. I also desolder U7 & U8, to check pads and via under these chips. The area seems to be ok. I get +5V on the pin 2 of U8 (while in standby) and a ~1 second pulse on pin 26 of U7 when I try to power the computer using an ADB keyboard. I'm pretty sure the problem is coming from the analog board (already fully recaped). Because the SMPS doesn't seem to be able to start (it stops when starting, I can hear it). I also tried to keep the Mac plugged during some hours, one of the transfo

Hello, I reply to myself. Bomarc schematics are not accurate. The +5VSB shown in the picture is the +12V PSU for the floppy drive. So this is normal to have them connected together. After a long investigation on the logic board, the problem doesn't seems to come from this part. More to come....

Hello bibilit, Merci pour la réponse (I'm french too). I made more investigations on the logic board and I spotted some potential issues and I have several questions: Can we trust BOMARC schematics for the logic board? If yes, using the schematics, I found some shortcuts with power supply lines. In the attached picture, I highlighted three locations: - Yellow : this is the +12V comming from the PSU - Red : Should be the +5V standby (+5VSB) (provided when computer is off) - Pink : Unknown. I expected to be tied to the +5VSB I tested

Hello to everyone, This is my first post on 68kmla :) I recently acquired a Classic Color and I have some issues with the power supply. I recapped the analog board, and changed opto-couplers. After recapping I've 4.85V on the ADB connector. When I try to power using the keyboard, I hear a click and nothing more happens. When I remove the logic board, I can hear an "electrostatic" noise from the CRT but the PSU stops just after. Does the analog board starts every times without logic board? Is there some known components causing this