I checked Q75 with the multimeter. I think he is good. What's there another method for controller it?
What would be the best solution to solve my failure?
What is the remote terminal DC voltage?
On the vertical board find C71-47UF/16V. Measure the DC voltage on either side of the cap. With the black probe on power ground,the negative side of cap should be ~5.5volts DC. On the positive side of cap you should see ~12volts DC. If you have probes in place and then power up the amp, you should see the voltage on the positive side of ramp up and then latch.
Also, measure the DC voltage of the 6 vertical board pins, again black probe on power ground. Post all of your results.
If this all checks out and you have ~12v DC at the base of Q75, then Q75 may have failed or there is a bad trace or via and you can trace the trace with an ohmmeter. A quick check from the collector of Q75 to the cathode of D92 will determine if you have a bad connection through the board.
On the vertical board find C71-47UF/16V. Measure the DC voltage on either side of the cap. With the black probe on power ground,the negative side of cap should be ~5.5volts DC. On the positive side of cap you should see ~12volts DC. If you have probes in place and then power up the amp, you should see the voltage on the positive side of ramp up and then latch.
Also, measure the DC voltage of the 6 vertical board pins, again black probe on power ground. Post all of your results.
If this all checks out and you have ~12v DC at the base of Q75, then Q75 may have failed or there is a bad trace or via and you can trace the trace with an ohmmeter. A quick check from the collector of Q75 to the cathode of D92 will determine if you have a bad connection through the board.
Hello,
Apologize for the delay, I've check what you asked me.
For C71 that's exactly what you described.
To measure the voltages on the 6 pins, here are the measurements starting from the Q75 side:
Pins 1 = 11.39V
Pins 2 = 11.22 V
Pins 3 = 10.24
Pins 4 = 0.028
Pins 5 = 0.003V
Pins 6 = 11.51V
I have 12V on the base of Q75 and no continuity of the collector at the cathode of D92.
Q75 is dead? His remplacement is necessary?
Thank you for your helps.
Okay, I'll order the transistor and I'll give you some news when I replace it.
Thank you for your help.
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