I did a re-cap of the analog board on my Classic II as it was having some power issues with a wavy like screen (you could see a ripple roll down the monitor slowly).
Replaced all radial electrolytic capacitors, put it back in the Mac and still having issues with it. Worth noting I am testing with a cleaned and recapped Classic Motherboard that works fine on another machine.
When initially powered up, I got a glitched/ garbled checkerboard, and it wouldn't boot. Then after a few moments it would boot, but it would restart the moment you touched the chassis and you would here the boot up beep -- The screen also shrunk and dimmed when this occurred.
Thought it was a grounding issue, so being I live in an older house - some outlets are not grounded properly. I plugged it into an outlet near the panel that I know for a fact has a working ground and the Mac refused to boot at all when grounded properly, and gave just a checkboard pattern.
Checked the 5 volt and 12 volt rails through the floppy connection on the back and both were low, so I adjusted the P1 pot until they came up to 5v and 12v (within .01 volts). After this the Mac would reliably boot up and no longer had a wavy screen -- however power would drop on both rails if I touch the chassis / ground plane (fan would spin down, hard drive slowed, screen dims).
On one boot, after it got to the desktop, I plugged a ADB mouse in and got a sad mac. Wouldn't boot after that, back to the garbled checkboard pattern. Put the good logic board back in its original Mac Classic, and after power cycling it a couple of times it worked again, and didn't have any issue with a sad mac or crash.
I also checked and double checked and all capacitors are facing the correct way (polarity).
Has anyone experienced something like this? Anyway to recover this analog board?
Replaced all radial electrolytic capacitors, put it back in the Mac and still having issues with it. Worth noting I am testing with a cleaned and recapped Classic Motherboard that works fine on another machine.
When initially powered up, I got a glitched/ garbled checkerboard, and it wouldn't boot. Then after a few moments it would boot, but it would restart the moment you touched the chassis and you would here the boot up beep -- The screen also shrunk and dimmed when this occurred.
Thought it was a grounding issue, so being I live in an older house - some outlets are not grounded properly. I plugged it into an outlet near the panel that I know for a fact has a working ground and the Mac refused to boot at all when grounded properly, and gave just a checkboard pattern.
Checked the 5 volt and 12 volt rails through the floppy connection on the back and both were low, so I adjusted the P1 pot until they came up to 5v and 12v (within .01 volts). After this the Mac would reliably boot up and no longer had a wavy screen -- however power would drop on both rails if I touch the chassis / ground plane (fan would spin down, hard drive slowed, screen dims).
On one boot, after it got to the desktop, I plugged a ADB mouse in and got a sad mac. Wouldn't boot after that, back to the garbled checkboard pattern. Put the good logic board back in its original Mac Classic, and after power cycling it a couple of times it worked again, and didn't have any issue with a sad mac or crash.
I also checked and double checked and all capacitors are facing the correct way (polarity).
Has anyone experienced something like this? Anyway to recover this analog board?