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voltage checks (of crt pins) are in order to diagnose CRT brightness problems. this will point to what area to look into.
common problem to watch for on ALL ctc-12 thru 17 at least are chroma board ground stakes and Jumper wires that run on the top of the pcb. checking the -y amp plate load resistors for heat would be a good start as well.
Question for Dave C, did you replace the .01 grid coupling caps of the 6GU7 -y amps? EVERY rca of the era had a problem with the cap that is between the tube and the power resistor (the middle 6GU7 tube). It would test "funny" not leaky but the eye tube would be fuzzy. The two other -y grid caps were often fine, I assumed it had to do with the hot evviroment (sandwitched between the tube and power resistor). While it did not seem to matter, I would replace it anyway (no real change was noticed in the pic). My read on this is the cap is not only responsible for passing the chroma signal but also part of the DC restoration (rather than the more common use of a diode).
cycle the bias adj and service setup switches a few times.
wiggle tubes on chroma board.
check jumper wires
confirm CRT pin voltages
check HV
Last edited by DaveWM; 08-29-2013 at 10:38 AM.
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