Resistor or jumper at hv rectifer socket: Zenith 25mc30

[Electronic M]

Originally Posted by Tubejunke

OK, it's official! My HV is back. The surgery was a success thank goodness. I was a bit nervous of what new surprises may arise, but the only changes were definitely positive. Good, stable HV with no corona hissing and/or related screen anomalies.

I did use Electronic M's advice and paralleled a .47mfd cap across my meter leads measuring cathode current at the horizontal output tube. The readings were the same and unfortunately still a bit higher than I want, or Zenith wanted for that matter. The spec is 200mA and at line potential upward of 120VAC I get about 220mA. So I still run the set on my Select a Volt at about 110VAC and can maintain 200mA. Once an older tech said that they used to dip all the Zeniths at 210mA as a rule, but I feel that I should be able to achieve the spec. Now I do believe that the fly is now running much cooler for whatever reason. VERY happy there!

I probably just need to change out the HO coupling cap to get the 200mA. That should be next because for whatever reason I have to throw a bit more line voltage at the set before the color will come in. Once it comes in I can back it down. The color problem has been with the set since I brought it home. Actually, there was no color for a long time and I changed out the 6GH8 one day and had a DVD player hooked up and wa la. Great color!

For now though I'm just glad to have a playable set again. Many, many thanks to all for the help on this!

Have you tested all the tubes in the color section? If not I recommend doing so. My set had no color, then I tested the tubes in the color section, and found most were testing bad to very weak. After replacing all the color tubes that did not test decently the color section came back STRONG.