Classic 2 logic board repair

[Redsward]

So I have 3 classic 2 LB’s . 1 works perfectly after a recap and bath . The second one does not chime and the screen stays black . It’s been recapped , the traces look great , little or no cap leakage I can see. Where should I start looking to get it going ?
Thanks in advance !

 

[lfletche]

Hey @Redsward, check out Mac84’s recent stream - Steve is doing some work on a Classic II and there is some great troubleshooting tips in it which may help you out here - especially the tip about the power connector: https://www.youtube.com/live/vnAtXpDoirQ?feature=share

 

[Redsward]

Thanks will do! My good logic board went the same way last night so now I am looking suspiciously at the Analog board.

 

[lfletche]

If you're analog board has not been recapped and is still original, then it most certainly will need to be.

The good thing about the classic analog board, though is you can check the voltages easily using a multimeter on the hard drive power connector. So as a starting point I would make sure you've got 5 and 12 volts there.

 

[Redsward]

The board is recapped , the opto's replaced (thanks to @pocketscience for that tip !) also a couple of diodes . It booted fine a dozen or so times (30 year old hard drive came back to , that was a surprise!) but now black screen and no chime but the fan runs . Going to run some voltage tests tonight .

 

[Redsward]

Annnd we are back. The Mac decided to boot again last night with my one good board . So now I think the black screen no chime may not be about the logic board , may be the analog board . Voltages are good ... so tonight I will try the other board again . I am a bit suspicious of a blue scsi I built and is not working as I screwed up the orientation of the blue pill and had to remove it , but it got powered up a few times so may not be happy .

 

[Redsward]

Well the Mac Classic 2 is currently booting reliably (still off the internal drive for now ) using my number 1 board. I reflashed the blue scsi but the system refuses to boot from it even if I externally power it so not sure what is going on with that .
So I inspected my 2nd Mac Classic 2 logic board ( I have 3 ) and it is in perfect condition absolutely no trace damage I can see , I have recapped it . It was booting to a gray screen so I was told it may be the rom , tonight I reseated them and used the ram from my good board just in case ,I got a chime and I made it to the welcome screen . But before I could celebrate the screen went black . Now I just get a black screen every time I turn it on with that board. Any advice greatly appreciated !

 

[rikerjoe]

I restored a Classic II about a year ago that exhibited the gray screen but no cursor. I wrote about my experience here, see if this might help at all. https://tinkerdifferent.com/threads/adventures-in-classic-ii-repair.1149/