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Macintosh 512ke wobbly screen

Cardoth

New member
Hey guys

I’ve brought a Macintosh 512ke (240v version) but I’m having some problems with a wobbly screen when the machine is cold, after about 15 minutes the screen stabilizes

I’ve changed all the capacitors on the analog board and have also changed CR20 with a MBR1045, CR21 with a MUR410 and Q2 with a BU406

I’ve checked all the board for dry joints and have reflowed any I found.

I have tried heating up and freeze spraying parts of the board and found U3 seemed to cause the wobbly screen to go when heated up and come back when freeze. I have changed it with a 4N35 and this doesn’t seem to fix the issue so I think we can eliminate this component as a problem…

I’ve checked the 5v and 12v lines and there giving me 4.97v for the 5v and 11.60v for the 12v these seem to stay the same cold or warmed up.

Does anyone have any other ideas?
 
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