I have been tearing my hair out on this. Can anybody help???
Turn the amp on with a signal generator (1kHz sine wave)in either channel and a square wave appears on pins 1 and 6. The chnl 1 volume control jumps up to max (although volume is obviously choked up) at about 1 on a scale of 10. Observing the sine wave on an o scope anywhere from input jack to pin2 of V1 and turning on the voltage switch only (no HV) and you can watch the top 1/3 of the sine wave decrease and flatten out
If I remove all but V1 and leaving the standby sw off (in stndby) the sine wave on pin 2 will clip on the plus side by about 35%.
Removing the tube still displays a sine wave on pin2 a small sine wave (same Sig Gen signal) on pin 1 (as well as pins 7 and 6)
I put my Fluke DVM on pin 1 of the socket (DCVolts) and watched the voltage rise slowly to about 6 volts. I reinstalled the tube and the voltage went slowly down. I jumped the filter caps (plus side) to ground and watched the sine wave regain it's normal shape and size when the filter caps had bled off to 0 volts). How come they are charging at all with the standby switch off? I'm about to replace the coupling cap at the plate of V1 (C11 0.01uF)I have replaced K1 and 2 I have checked the resistor values of all V1 circuits. I have looked at grounds of all components associated with v1. I have changed the tube twice. [I] replaced C1 (Dielectric 22uF 25V cap) and R5 1500 Ohm res. The amp has had a couple of mods done to it. R's 5, 10, and 12 have been doubled from 1500 to 3Kohms and the filter caps have been changed.
Turn the amp on with a signal generator (1kHz sine wave)in either channel and a square wave appears on pins 1 and 6. The chnl 1 volume control jumps up to max (although volume is obviously choked up) at about 1 on a scale of 10. Observing the sine wave on an o scope anywhere from input jack to pin2 of V1 and turning on the voltage switch only (no HV) and you can watch the top 1/3 of the sine wave decrease and flatten out
If I remove all but V1 and leaving the standby sw off (in stndby) the sine wave on pin 2 will clip on the plus side by about 35%.
Removing the tube still displays a sine wave on pin2 a small sine wave (same Sig Gen signal) on pin 1 (as well as pins 7 and 6)
I put my Fluke DVM on pin 1 of the socket (DCVolts) and watched the voltage rise slowly to about 6 volts. I reinstalled the tube and the voltage went slowly down. I jumped the filter caps (plus side) to ground and watched the sine wave regain it's normal shape and size when the filter caps had bled off to 0 volts). How come they are charging at all with the standby switch off? I'm about to replace the coupling cap at the plate of V1 (C11 0.01uF)I have replaced K1 and 2 I have checked the resistor values of all V1 circuits. I have looked at grounds of all components associated with v1. I have changed the tube twice. [I] replaced C1 (Dielectric 22uF 25V cap) and R5 1500 Ohm res. The amp has had a couple of mods done to it. R's 5, 10, and 12 have been doubled from 1500 to 3Kohms and the filter caps have been changed.
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