HMV 2304 Racord player/Radio combo.

[pwdrive]

Hi Lawrence, I'll check that tomorrow, have you got any idea where the negative voltage can come from though?

Thanks, Dave.

Under normal conditions the bias for the V3a will be due to grid current bias so far as I can make out, and the voltage developed across the cathode resistor would be minimal, wouldn't have thought more than around 0.2 volts or so across the cathode resistor, the grid current for the grid current bias will be tiny, hence the high value grid resistor that is used.

I've known hum to be caused by PCB leakage, often if it's been subjected to heat and discolouration has occurred.

Lawrence.