Mod50 no sound

[ned]

Not getting any sound out of my Mod50.


Checked bias and mine was right the acceptable range, but still getting no sound regardless of what module I try. Wondering if this is a 12AX7 issue. How do you check?

Pulled tube covers off. V1 glows. The AT7 in the loop buffer and the AX7 in the phase inverter position do not glow.

Any ideas? Bad phase inverter?

 

[kc2eeb]

First, swap out the tubes and see what happens. Then, I believe the heater voltage is DC from U1 Voltage regulator on the power supply board.
So, check pins 4 and 5 on the tube sockets for 12 volts DC. The heaters are wired in series, I believe. Also, there is a 4-40 ground screw that must have continuity to ground on the Power/filter cap board. Hope this helps.

 

[ned]

I inserted a jumper cable in the serial loop and everything works fine now. Will get some contact cleaner and clean the loop jacks later this week.

 

[kc2eeb]

I was going to say check the effects loop but you said the PI and effects T7 didn't light up.
Figured you would have checked the loop already. In any event, glad it's working.