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Old 29th Feb 2020, 3:34 pm   #5
Techman
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Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 3,392
Default Re: Pye VT4 - no EHT

I agree, but un-solder and remove the EY51, or at least disconnect one side of its heater before checking the continuity of the few turns of heater winding on the transformer or trying to power the heater from a separate supply. If you power the heater with it connected to its supply winding, you'll short out and possibly damage your supply due to the very low resistance of the winding. You could check the continuity of the heater with a meter once it's disconnected, but this won't tell you if the valve actually has no emission due to ingress of air, where the heater will still have continuity, but will not glow.

From what you say about a poor spark from the tops of the PL and PY, it does sound a bit like somethings damping the whole output stage and this could be just a damp transformer - I'm sure you've read the instructional threads on how to deal with this. It could be a leaky boost capacitor or coupling capacitor to the PL. At worst it could be the LOPT has failed somewhere on its overwind, but hopefully not - dry it out first if you haven't already done so.
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