Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: joesatch on October 22, 2022, 07:22:32 pm

Title: help with input stage plate voltage issue
Post by: joesatch on October 22, 2022, 07:22:32 pm

So i have this part of a schematic not behaving as expected.  With the switch engaged (ground after the 1M), i get 100V plate (pin 6, good.). With the switch disengaged i get 10V at the plate (not good). This channel should be muted with switch engaged but disengaged only getting 10V on the plate.

Title: Re: help with input stage plate voltage issue
Post by: sluckey on October 22, 2022, 07:33:48 pm

The plate voltage should not change regardless of the position of the switch, unless... that 1M resistor is really not connected to ground. Or some other wiring error.

Title: Re: help with input stage plate voltage issue
Post by: joesatch on October 22, 2022, 08:03:15 pm

it's connected to ground. the interesting thing is in the circuit the 1 meg reads 280 ohm (powered off)

Title: Re: help with input stage plate voltage issue
Post by: sluckey on October 22, 2022, 08:07:15 pm

Quote from: joesatch on October 22, 2022, 08:03:15 pm

it's connected to ground. the interesting thing is in the circuit the 1 meg reads 280 ohm (powered off)

It ain't wired like your schematic.

Title: Re: help with input stage plate voltage issue
Post by: joesatch on October 22, 2022, 08:27:04 pm

i figured it out. i had the negative on the switch shared with a relay negative (power). when in doubt start disconnecting things i guess.