Quote:
Originally Posted by peverett
I had AGC troubles with a 1977 vintage Portacolor. The symptoms were intermittant. What would happen is that the picture and sound would go away leaving just a raster. What I found was that the design of this particular Portacolor had controls with the boost voltage (700 volts if I remember correctly) and the AGC controls in the same assembly. Over time, conductive tracts had built up, allowing the boost voltage to leak into the AGC area.
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Thanks very much. I believe you are alright. I have operated the set with shortened filaments of the 11BT11 (AGC keying), i.e. the 11BT11 not operating. I found 0.6V at the anode. (Pin 9). With heated 11BT11, I found -60V. In a quiet room I hear some muted cracking noise from the AGC control assembly. I will remove it and clean it like you have suggested.
- Eckhard