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Going through and checking the ceramic resistor against the schematic, I found that the 1 meg section between pins 1 and 10 is open. I replaced this by tacking a separate 1 meg resistor across the board. Unfortunately - no change. The set hasn't been intermittent in a while, now it's just always dim with no change from the picture control.
I did check voltages at the video IC 221-96 against the schematic, and they all seem about right, and I can adjust the voltage at pin 16 with the picture control.
I'm beginning to wonder if something in that chip might have failed - possibly due to the ceramic resistor having that bad section? Unfortunately I don't have another one of those chips, so I'm probably going to have to order one to try swapping it out. All the other components on the board test good, and every other section of the ceramic resistor checks OK on the meter.
-Ian
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