Mac Classic - will it ever run again!!

[rubber_jonnie]

Fingers crossed that it helps. At this rate you'll have a new analogue board effectively.

Yep, it certainly feels like that!!

What's annoying is that I'd have replaced the CN17 much sooner if I had been sent the correct parts to begin with, and then of course the correct ones were delayed over Christmas and New Year.

Never mind, they're here now, and I have QP2 on the way too, an IRF-BC40, just for good measure.

[rubber_jonnie]

Ok, I replaced the CNY17 at lunchtime, and it's looking like it may have finally solved the problem!!

I get 5v immediately, rather than 4.6 ish, so next I need to leave it to stand for a while to be sure it's in the condition of being standing for a while, which would normally mean it does the slow 5v ramp up to 4.88v where it boots.

I have tested it super quick, and I got a bong straight away, which is not normal, so I am hopeful!

[PhilC]

Nicely done Mr RJ

[rubber_jonnie]

Nicely done Mr RJ

Loving your optimism

[PhilC]

Nicely done Mr RJ

Loving your optimism

I have faith in you. If it's Bonged once, it might once again

[rubber_jonnie]

Loving your optimism

I have faith in you. If it's Bonged once, it might once again

You never know!!

[stephen_usher]

Yay! Sounds like you found the issue then.

[rubber_jonnie]

Yay! Sounds like you found the issue then.

I'll confirm once it's stood a while. If it's still misbehaving after that then QP2 is next on the list!!

I think I will need to make sure PP1 is properly set before I call anything done too, as dropping in the new opto may well require a tweak.

[rubber_jonnie]

OK, I powered up the Classic after sitting overnight, and guess what? It bonged and powered on right away,

Next I need to figure out why the screen has developed a wobble, probably the last remaining electrolytic capacitors that are getting replaced in the video circuit, and resolve the connection issues with the RAM board that sometimes works and sometimes doesn't.

So the culprit is looking like the CNY17 opto, but I've pulled dead caps out of this board, and there were a bunch of very leaky ones when I first started this project, so have no regrets about replacing them.

[stephen_usher]

Wobbling screens are quite often video cables going too close to a mains cable or somesuch. You may get away with just rearranging the cable routing inside the machine.