I need a diagnostician. Traynor YGM-3 issues.

jacklawtey

So I have this lovely old over-engineered heavy piece of shit and have been mostly enjoying it until it took an oath of silence. It powers on but nothing more, no crackle nor hum. Checked cables etc. 

I know, I know. I should take it to a tech but I wondered if there are some diagnostic procedures I can follow before resorting to that? 

Thanks!

ICBM

The most likely cause is a resistor in the power supply chain which feeds the screens - it’s one of the only weak points in the design. Pretty much every one of these amps I’ve worked on has had it replaced already, if it’s not the actual fault it came to me for.

Be careful if you’re metering round this part of the circuit, it’s at the full HT voltage.

DJH83004

As IC says, the YGM-3 doesn't have individual screen grid resistors, the supply is tapped off the main power supply, one dropper resistor down from the O/P TX centre tap, can't remember if it is 470 ohm or 1K something of that order. If it has gone open circuit I would drop in a 5watt replacement.