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Macintosh Plus CRT issue

Time for me to chime in!

jt: I adjusted the display to normal, WYSIWYG specifications, according to MRUS (7.11" x 4.75").

There were a few more items I suspected as being the cause of the problem, but I ran out time (I had to send it to markyb), so I couldn't investigate further.

It seems he's picking up where I left off.

I'll try to help where I can.

c

 
Any number of things. I'd first start by checking the voltages out of the power supply. Also check carefully for bad solder joints in the monitor circuitry, especially in the horizontal deflection section. Low anode voltage (the high voltage to the CRT) will cause the picture to expand. The HV circuit is part of the horizontal deflection circuit, and B+ in the case of these monitors is 12V IIRC.

 
onlyonemac: There are some square pieces of material (ferrous/magnetic, possibly) which control the shape of the picture. I did my best to equalize these before selling the machine to markyb, but they seem to be unrelated to the current problem.

There were several capacitors I didn't replace (I sort of wish I did). Some of those could be causing the screen to go weird.

c

 
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