Issues: 120vac in and using 1kHz sine wave
pentode and triode with bright switch- hum, no sine wave
pentode and triode with thick switch - hum, a little sine wave.
Measurements:
tag 4- 308vdc
tag 7- 325vdc
tag 8- 325vdc
tag 11- 308vdc
tag 12- 308vdc
V1,p9- 305vdc
V2,p9- 305vdc
q1-r1 328vdc
r1- tag4- r17 308vdc
r17- r16 169vdc
V3,p1 - 80 to 100vdc
V3,p6 - 80 to 100vdc
V4,p1 - 160 to 180vdc
V4,p6 - 109 - 125vdc
note r18 on the schematic is actually r17 on the board.
after r16 the voltages fluctuate about 20v.
Vox_NT15.pdf .
First thing I see is r1 is dropping too much voltage. It measures 1k ohms in circuit. Of course every voltage after that is low. Then after r16 voltage readings swing up and down 10-20 volts.
I would replace r1 but why is it dropping so much voltage if it is 1kohms?
r16 measures 7.8 k ohms in circuit.
I don't think filter caps are the problem since I get 328vdc on one side of r1.
Thursday I will take the board out and touch up the solder joints. If I have the proper resistor I will replace r1.
Any ideas on what is going on?
pentode and triode with bright switch- hum, no sine wave
pentode and triode with thick switch - hum, a little sine wave.
Measurements:
tag 4- 308vdc
tag 7- 325vdc
tag 8- 325vdc
tag 11- 308vdc
tag 12- 308vdc
V1,p9- 305vdc
V2,p9- 305vdc
q1-r1 328vdc
r1- tag4- r17 308vdc
r17- r16 169vdc
V3,p1 - 80 to 100vdc
V3,p6 - 80 to 100vdc
V4,p1 - 160 to 180vdc
V4,p6 - 109 - 125vdc
note r18 on the schematic is actually r17 on the board.
after r16 the voltages fluctuate about 20v.
Vox_NT15.pdf .
First thing I see is r1 is dropping too much voltage. It measures 1k ohms in circuit. Of course every voltage after that is low. Then after r16 voltage readings swing up and down 10-20 volts.
I would replace r1 but why is it dropping so much voltage if it is 1kohms?
r16 measures 7.8 k ohms in circuit.
I don't think filter caps are the problem since I get 328vdc on one side of r1.
Thursday I will take the board out and touch up the solder joints. If I have the proper resistor I will replace r1.
Any ideas on what is going on?
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