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cleaned the pots on the front, that cleared up all the sync issues. Tuner needs cleaning. the brightness pot needs to be turned up pretty high. I will be checking the 12GN7 video out soon, if its weak it can cause a CRT bias issue cutting off the crt. I tested the CRT and it tested very good so the high screen settings tell me something is a not right.
this set controls the brightness by biasing that 12GN7 thru the cathode with a 500 ohm ww pot and a 82 ohm resistor. On my other set that 82ohm had drifted up, which would increase the bias, causing the higher plate voltage and again upsetting the CRT bias. The Vert seems to shrink as it warms up, the vert out bypass cap sits right next to a big power resistor so it gets pretty hot from that. I will replace that one just because I dont like the high heat its getting. its in a single can, the PCB has holes for axial and a can in for that cap.
I think I can get to that 82 ohm resistor without pulling the chassis, its mounted right at the pot.
One last issue is the focus, varies from about 3.3 to 3.7 kv.
I plan to check the 66meg resistor, and maybe try a new focus rectifier.
I made up a 120pf cap to replace the 130pf 6kv that couples the output from the focus coil to the cathode of the focus rectifier. I have had issues with focus coils before when not using the EXACT replacement. Hope that is not the case here.
I would still like to try a HV silicon rectifier some day instead of one of the Se sticks.
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