Grundig 80U

[Amie]

Try and check the voltages when in the fault condition.

The grid bias for the triode section is by/due to grid current, the high value grid return resistor being the giveaway for that type of bias arrangement, the bias for the pentode section is provided by the current flowing through all the valves, that current has to flow through the 70 Ohm resistor (R16) The voltage developed across that resistor being the pentode's grid bias voltage, supplied via the 1 meg and 1k resistors, R15 & R14)

https://nvhrbiblio.nl/schema/Grundig_80U.pdf

Lawrence.

Thanks for the link Lawrence, I've tried to download it, but is still "queued"  I will look at what Greg attached and go from there, the capacitor at the top of the volume control, plus the one to the grid seem ok, but I've temporarily replaced them anyway and there's no difference.

Amie