Willsenton R300 Circuit Design Issue

Thanks for the advice. The resistor in the B+ is 150k.

I agree to remove the diode. Not sure how the 400V would be created though as the resistor already dropped the voltage to around 120V....I guess I need to look at the schematic again to try to figure out how it all works.

From what I understand when the diode shorted it grounded the B+ which is why I was getting a reading of zero volts on the 150k B+ resistor. That is why the preamp section died and no sound was produced.

I have built several guitar tube amps so am pretty comfortable working on this amp. Just not too up to speed on hifi design and had not come across a zener diode to regulate voltage in past guitar amp builds.

Thanks again!  I'll report back if the builder has anything else to add once I hear from them again.

Any more feedback on the efficacy of this repair? I may be ordering one of these amps, and want to make sure the repair you implemented is ok to do.

Thanks.....

That Zener diode should not have failed on its own. I would be suspicious of the filter capacitors that it feeds.

Does anyone have a schematic of this amp? I'm about to dive into one of these to review and do a video series on and can't find one!

TIA

Skunkie