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Voltage tests on V4 indicate wrong voltage on pins 7, 8 and 9.
pin7: -5 vdc / .5 vac / Should be 0 vdc and 3.5 vac
pin 8: 177v / Should be 95v
pin9: 184v / Should be 130v
Resistances are wrong on pin 7 to B+ output according to the Sams.
Pin 7: 2.1kΩ and 3.4kΩ (Sams states R depends on polarity of probes)
R should be 130Ω
So, something's overloading the grids and plate on the Vid1 section and the tube can's cut off correctly. I have some ideas suspect dropping resistors and DC blocking caps before the Vid 1 stage, maybe even going back to the AGC...
Will also bust out my scope to verify the waveform on the Vid input. Maybe try different video injection points. I don't have an analyzer, so I have to do it by composite from the set top box.
Last edited by Jon1967us; 05-24-2021 at 03:47 PM.
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