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Originally Posted by cathoderay57
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There is measurable resistance between pin 6 and 7, about 30k
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That's not good, and most likely where the 100v is leaking from. If the valve holder is Paxolin or similar material, it can carbonize and turn resistive. If that's the case a valve holder replacement is probably necessary. |
This is becoming more common with the age of the sets. Most radios are stored (or have been stored) in less than ideal conditions and dampness plays a major role. Once the valve holder starts to 'track' (leakage between two pins usually where there is the greatest voltage difference) then it gradually gets worse and the tracking causes heat in a localised spot which gradually builds up causing the Paxolin to carbonise until it reaches a point where the leakage affects the operation of the valve.....
The only answer in that case is a new valve holder. Note that it's not only Paxolin valve holders that can track......