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#11
03-13-2015, 01:33 AM
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Here is the TV Analyst's horizontal grid drive signal. Very stable.
 I disconnected C115 at its junction with R138/R139 and injected the signal there. With tubes back in place, the screen grid voltage at pin 1-8 dropped from 350V+ to around 125V (160V expected) and the HOT did not red-plate. The voltage at grid pin 4-5 was -75V instead of the expected -38V. Out of curiosity, I reconnected C115 and tried the set without the injected drive signal. The HOT red-plated and I shut down immediately. Which suggests something fishy upstream of the HOT, I guess. This was done on the workbench. I suppose I could set the chassis behind the cabinet and connect to the CRT with this setup, if it's important to look at the screen and judge whether the flyback is still alive. I don't have extension cables for the yoke/convergence/CRT, but the original cables reach if I put the chassis on a big box. It's just hard on the back to crouch down on the floor to measure things  Phil Nelson 
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