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There is sound, line whistle, and all the valves light up
except for the DY87 e.h.t. rectifier. Also R77 is overheating.
The overheating of R77 has nothing to do with the loss
of e.h.t. It’s the field output valve’s cathode bias resistor and
the trouble is probably due to this valve being faulty. For
the e.h.t. fault, first lift the DY87’s top cap: the valve could
be shorted internally. If this is not so lift the PY800 boost
diode’s top cap. If this action restores some life to the line
output stage change the boost capacitor C97 (0.1fil,F) which
could well be short-circuit. Otherwise, the line output
transformer could be at fault. (Pye 11U series.)

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