68kMLA Classic Interface

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SE/30: distorted picture

Posted by: bobo68 on 2017-02-03 09:16:24 Hi, I purchased an SE/30 which runs fine but the monitor picture is vertically compressed (more on the left side, less on the right side). It stays the same even when the SE/30 warms up. Is this a problem on the analog board or at the monitor yoke? Any hints are much appreciated. Best, bobo68

Posted by: olePigeon on 2017-02-03 09:26:42 Probably bad caps on the analog board?  I was going to suggest fiddling with the vertical pot, but the fact that it's distorted unevenly is weird.  You could try fiddling with the adjustment rings on the yoke.

Posted by: Bolle on 2017-02-03 09:36:44 The pots are supposed to not to do anything when turned according to the seller. I would suspect those to be broken and pulling down deflection voltage.

Posted by: bobo68 on 2017-02-03 11:51:11 Yes, he wrote that he could not regulate the height of the picture with the pot. That is one thing. I'm more worried about the uneven distortion. Maybe it is the deflector magnets? P.S. How did you find the ad?

Posted by: Bolle on 2017-02-03 12:10:00 Constantly monitoring everything vintage Apple on ebay.de  😉 The uneven distortion could be magnets indeed. But setting those up again to give even edges is possible, I just did this on an SE. It took its sweet time and a lot trial and error but now I am only left with a minor curve on one of the edges, which was ok for me.

Posted by: apm on 2017-02-03 13:22:10 I'd start with C9 on the analog board. It's the big electrolytic cap in series with the vertical deflection coil. The warped picture could be magnets if the seller messed around with them, otherwise I don't see how they would have gotten out of alignment. If those are still glued, and it's not C9, then I'd look at the yoke itself. The warp could be some of the horizontal coil signal leaking into the vertical coil, which could imply a short between them. I'm not sure how that would happen but I suppose it's possible. You could test it by checking the resistance between the vertical and horizontal coils with the yoke disconnected. Anything less than infinite would suggest a bad yoke.

Posted by: bobo68 on 2017-02-04 02:40:05 I asked the seller: he did not change the caps on the analog board (but on the main board) and did not manipulate the crt magnets or yoke.

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