Macintosh 128k Restoration: Help!

[sadmanonatrain]

Hello all,

I've replaced all the resistors mentioned in a previous post and I am still getting nothing from the Macintosh.

The 'Dead Mac Scrolls' points towards the Flyback Transformer as being as being a potential fault. The flyback installed currently is a 157-0026-B.

Larry Pina says if the resistance across CR5 is not 3.6k the flyback is at fault. The reading I get is 0.03.

I have a Macintosh SE/30 which is currently without a CRT. So, I was thinking if I could transplant the SE/30's flyback into the 128k. The SE/30's flyback is a 157-0042C. I believe they may be compatible.

Perhaps this would be a solution to the problem?

Thank you!

 

[sadmanonatrain]

Hello all,

I've transplanted the 157-0042C into the Macintosh but that has not solved anything.

Back to the drawing board!

Now, TDMS suggests the replacement of CR5 with a heavy duty MR824.

 

[techknight]

instead of swapping parts, try pulling the components 1 at a time, and test them. Youll never find the fault if your shotgunning, unless you replace every little single component humanly possible on the analog board. But by that point, youll have another analog board.

 

[sadmanonatrain]

Hello all,

I have replaced CR5 with the aforementioned component but I am still getting nothing from the Macintosh.

Do the leads of CR5 and CR21 need to be in contact with the metal heat sink?

I think I'll call it a day with this Macintosh for the time being!

Thanks for all the help!