Restoring a RCA 21CT55

[etype2]

Originally Posted by miniman82

What is your HV reading with the HV control at max? It’s not uncommon to have to play with the value of the resistors around the HV pot, since any drift there will cause the grid of the shunt tube to not be where it’s supposed to be which drags down the anode.

We replaced a resistor in the HV regulation circuit which was found open. This caused the HV to drop to 10KV and messed up the picture badly. The resistor was an original (made by International Rectifier) special film type, 3.4 Megohm 3 watt. We replaced it with QTY 2 (in series) OHMITE 2.2 Megohm 2 Watt film type which now makes the new resistor a 4 watt unit which is a 25% upgrade for power dissipation.