SA-6500II power supply problem s
- Thread starter The Fuxtor
- Start date
Watthour
Electron Rancher - JS3600
I suspect it is.
The Fuxtor
Addicted Member
In diode function I only read 0.547 and 0.615 for voltage?
The Fuxtor
Addicted Member
Yup! I did come to the conclusion that the new stv's are good. My meter crappy! Very reputable seller
The Fuxtor
Addicted Member
Under power?
Yes, using the voltmeter function. Never ohmmeter or diode test when powered.
The Fuxtor
Addicted Member
Sorry for my ignorance, black probe chasis and red probe anode- record voltage then red probe cathode and record voltage and compare?
You can measure the voltage with one lead on each of the STV leads. That will provide the voltage drop across the device.
Red probe on one STV lead, Black probe on the other STV lead.
The Fuxtor
Addicted Member
Ok one channel shows 1.18v drop
The other channel showing only ,20mv max?
The other channel showing only ,20mv max?
The Fuxtor
Addicted Member
I'll check. Orientation matches other channel. I have a few spares I could sub in.... I'll check the those 2 diodes soon!
The Fuxtor
Addicted Member
Stv orientation correct, D8 reading 0.453v drop but D7 gives me a reading of 0.503 but isn't stable? Jumps about in the 100mv range then hits 0.503 and repeats the unstable readings...
D10 reads 1.454v drop , D9 still only approx 20mv? Swapped a replacement stv here...
I spent another hour n half later last night just checking resistors but nothing out of spec...
Last edited:
Sounds like you still have a left channel amplifier problem.
You mentioned earlier that the outputs were pulled. Are they still out? Both channels? Are they defective? With the outputs removed, the feedback path is interrupted which will affect the DC operating point voltages.
If the right channel is stable, you could start comparing transistor ECB voltages for Q11/Q21 (L) and Q12/Q22(R).
You mentioned earlier that the outputs were pulled. Are they still out? Both channels? Are they defective? With the outputs removed, the feedback path is interrupted which will affect the DC operating point voltages.
If the right channel is stable, you could start comparing transistor ECB voltages for Q11/Q21 (L) and Q12/Q22(R).
The Fuxtor
Addicted Member
All outputs are dedoldered still. I'll take some measurements of what's happening there! Thanks again!!
Outputs are still good .
The Fuxtor
Addicted Member
ok.
Q11
E -30.5v
C +0.249v
B -30.8v
Q12
E -31.1v
C +0.252v
B -31.1v
Q13
E -50mv ( unstable/ jumpy)
C -100mv ( unstable/jumpy)
B -0.715v
Q14
E -14mv
C -104mv
B +0.245v
Q15
E +0.239v
C +174mv
B +0.958v
Q16
E +193mv
C +178mv
B +0.942v
Q17
E -52mv
C -108mv
B -105mv
Q18
E +52mv
C -104mv
B -105mv
Q19
E -55mv
C +64mv
B +0.221v
Q20
E +45.8mv
C +63.7mv
B +0.201v
Q21
E +15.30v
C +0.954v
B +14.61v
Q22
E +15.24v
C +0.931v
B +14.65v
Q11
E -30.5v
C +0.249v
B -30.8v
Q12
E -31.1v
C +0.252v
B -31.1v
Q13
E -50mv ( unstable/ jumpy)
C -100mv ( unstable/jumpy)
B -0.715v
Q14
E -14mv
C -104mv
B +0.245v
Q15
E +0.239v
C +174mv
B +0.958v
Q16
E +193mv
C +178mv
B +0.942v
Q17
E -52mv
C -108mv
B -105mv
Q18
E +52mv
C -104mv
B -105mv
Q19
E -55mv
C +64mv
B +0.221v
Q20
E +45.8mv
C +63.7mv
B +0.201v
Q21
E +15.30v
C +0.954v
B +14.61v
Q22
E +15.24v
C +0.931v
B +14.65v
There's a lot to digest here. Clearly, there is something going on around Q13 which I believe you replaced with a C2690. One thing I noticed is that the base voltage of Q13 is different than the collector of Q11 but they should be exactly the same since they are connected together. Perhaps try another replacement for Q13.
It would also be interesting to see the voltage drop across R83 and R84 which would provide an indication of the current being drawn from the regulated 34V source.
It would also be interesting to see the voltage drop across R83 and R84 which would provide an indication of the current being drawn from the regulated 34V source.
The Fuxtor
Addicted Member
Q13 was replaced with a ksa1220ay.
R83 shows 7.31v drop
R84 shows 7.52v drop.
I'll pull q13 and try another one in there
