Stromberg Carlson 21TQ restoration

[bandersen]

Originally Posted by Electronic M

Could the detector diode be plugged in backwards?

That was the first thing I thought of too No, switching it screws it up even more. I discovered that this problem has existed all along. When I injected a signal directly in the IF, I had the contrast up 100%. If I back it off a little, I get a reversed test pattern too. The service specifically mentions an inverted image in the troubleshooting section and indicates it's a problem in the video amp.