Recently bought this amp and when I hooked it up C39 pretty much blew up and let out alot of smoke. I took the circuit board out and replaced the capacitro and turned the amp on for a few seconds then turned it off and when I touched C39 it was very hot.
I have followed traces testing everything in the circuit and everything tests good and I don't have a oscilloscope at the moment so my testing is limited.
I have followed traces testing everything in the circuit and everything tests good and I don't have a oscilloscope at the moment so my testing is limited.
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They all check out good, I downloaded the service manual and Q65 that ties into everything there controls the high side power supply regulation
Q65 takes its supply from the output of those 4 diodes, which is filtered by that capacitor. Unless Q65 is in some way passing high voltage back to that capacitor (not likely), it's not likely to be the reason for the cap heating up.
When you checked the diodes, did you desolder (at least) one terminal and check each of them for leakage?
When you checked the diodes, did you desolder (at least) one terminal and check each of them for leakage?
I took all 4 completely off and checked them and they all check out fine no leakage with probes reversed.
I put them back on and was curious how much power is going to the capacitor and when powered on it started about 85 volts and dropped down into the 70s. I only left power on for about 5 seconds to get a quick reading
I put them back on and was curious how much power is going to the capacitor and when powered on it started about 85 volts and dropped down into the 70s. I only left power on for about 5 seconds to get a quick reading
no had my negative probe on the negative terminal of the amp and the positive on the positive of the capacitor
This part of the circuit is a 15v regulator that's used for the drive circuit. It's referenced to the positive rail so it's best to measure directly across the capacitor.
desolder one terminal of the 4 diodes and measure the AC voltage across the two traces that feed those diodes.
For reference, also measure the AC voltage from ground to the outer legs of one of the main rectifiers (D21/22).
Post those voltages.
For reference, also measure the AC voltage from ground to the outer legs of one of the main rectifiers (D21/22).
Post those voltages.
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