Mac Classic - will it ever run again!!

[exxos]

Gosh those are a blast from the past. I guess it depends what they are across ? I know the ones I had were mostly 160v but thinner that that one. Though some rated AC or DC voltage. I forget which way it was, but it was like 630VAC or 315VDC kinda thing. I'll try and see what mine say when I get home. I think they were made by Phillips ? Can't exactly remember now.

[stephen_usher]

That looks a bit like a dipped, non-RIFA X2 cap.

[exxos]

Looking at evilbay https://www.ebay.co.uk/itm/Philips-MKT3 ... ect=mobile

250V then the "dot" so yours I assume is 63v like you thought.

[rubber_jonnie]

That looks a bit like a dipped, non-RIFA X2 cap.

Definitely non RIFA, though this board did have RIFAs that were on the verge of releasing the smoke and I replaced those when I first started looking at the analog board. CP25 & CP27, so part of that left hand PSU circuit.

[rubber_jonnie]

Looking at evilbay https://www.ebay.co.uk/itm/Philips-MKT3 ... ect=mobile

250V then the "dot" so yours I assume is 63v like you thought.

Hmm, yes, that would make sense.

Bloody annoying all these different methods of identifying capacitors!

[Tomswork]

I agree with the capacitors marking nightmare and the apple's love of y and x class capacitors in the macintosh line

Tom

[Tomswork]

@rubber_jonnie

Have you looked at the opto coupler qp1 it may have a thermal problem

Tom

[rubber_jonnie]

@rubber_jonnie

Have you looked at the opto coupler qp1 it may have a thermal problem

Tom

I am waiting for replacement optos to arrive. I did order some, but was sent surface mount in error rather than the DIP packages needed. New ones are on the way, there isn't really much left to replace.

I've replaced the TDA4605 and recapped the entire board with a few exceptions like the small ceramics, so the opto is really the last main part of the PSU section to be replaced.

It's so annoying that I have CNY17s that simply won't physically fit. Parts are due Wednesday. I'll replace in the evening if they arrive on time.

If the problem persists after I replace that, I will have to start looking at the other components around the TDA and CNY, and I think I should consider replacing QP2, which is potentially common to both the 5v & 12v lines.

EDIT: IRF-BC40 replacement for QP2 on order.

[rubber_jonnie]

Woo hoo, my CNY17s arrived this morning, so I will drop one in tonight, see if that helps!

[stephen_usher]

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