Back in the days of fixing vacuum tube TV sets, the diagnosis was No Picture, No Sound.
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Show posts MenuQuote from: gbono on March 31, 2021, 12:07:28 AM
One side of R316 is at 83V and between R316/7 I get 43V but on the other side of R317 it's sitting at 4V. I have lifted one side of CR308 (zener) which doesn't change voltage at node - what is dropping the voltage? All measurements referenced to minus terminal on C403.
Quote from: gbono on March 30, 2021, 05:43:29 PM
Voltages around Q303 are:
VC=4.3
VE=1.9
VB=2.6
I'm still seeing LT 3V at C404.
Quote from: gbono on March 29, 2021, 02:07:40 PM
Rechecked voltages around Q303
VC=1.9
VE=.18
VB=0
I have replaced this transistor several times with 2N3440...
Quote from: gbono on March 29, 2021, 02:07:40 PM
Voltages around Q204
VC=4.37
VE=1.9
VB=2.67
Quote from: gbono on March 28, 2021, 10:35:07 PM
Voltages around Q303
VC=.8
VE=2.5
VB=.2
note: Q303 previously replaced by 2N3440 250V/1A/TO-3 very similar to 40409/8
Quote from: gbono on March 28, 2021, 04:44:19 AM
I thought that if the base voltages vary then the collector currents would also vary but the emitter current (total) would stay the same.
Quote from: gbono on March 28, 2021, 04:44:19 AM
With 3.6V on the emitters of the dif pair then Q301 would be off and Q302 would be on - correct?
Quote from: gbono on March 28, 2021, 04:44:19 AM
How is Q303 biased? Isn't Q301 supplying bias to Q303?
Quote from: gbono on March 28, 2021, 04:44:19 AM
Still not able to explain why the voltage at C404 isn't at VCC/2?