I'm thinking that there is a problem in the horizontal blanking circuitry, the link that goes from the
flyback transformer to the video. (R16, CR4, etc.) Maybe an open cap is allowing the blanking
signal to 'ring'? If you have an oscilloscope it would be useful to look at the signal in that area.
Hope that is helpful.
Bill.
:-)(((
On Jun 28, 2014, at 5:12 PM, James MacPhail <gg__at_email.domain.hidden> wrote:
Examples of Ken's Lisa symptoms are here:
http://members.shaw.ca/sigmaseven/boylephoto1.JPG
http://members.shaw.ca/sigmaseven/boylephoto4.JPG
The symptom is the wide dark vertical bars at the left third of the screen (ignore the gibberish image in the second picture).
I suspect the problem is related to the +28V supply on the video board, but perhaps someone knows more specifically what part needs to be changed?
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Received on 2014-06-28 19:58:05
