ranukic
Active Member
hey,
I replaced all of the board electrolytic capacitors, fixed the R33&R34 resistors for the protection circuit, found a bad transistor and fuse on the main power board and a couple other fuses throuhgout that I replaced. After all of this work and trouble shooting there is hum in the transformer that is resinating through to the speakers. At first I thought it was bad filter caps but when i scoped their and also checked the AC voltage at each cap I found it to be less than 0.89VAC which should be acceptable...
The only time the low harmonic ham changes is if i press the mute button, adjust the tones and turn the volume up so the music drowns it out. When the mute is pressed the sound completely is eliminated.
I took the jumpers off the amp out to in, hooked up a bluetooth device to the in and there was no hum. I do not recall if the transformer also stopped humming but I can check that again tomorrow.
The sound reminds me of the sound cheap rca cables make when hooking a phono to an amp but with just a little more buzz.
I am not convinced the problem is the transformer itself, i think there is a load causing the hum. Any suggestions on where the issue may be hiding?
Thanks, James
I replaced all of the board electrolytic capacitors, fixed the R33&R34 resistors for the protection circuit, found a bad transistor and fuse on the main power board and a couple other fuses throuhgout that I replaced. After all of this work and trouble shooting there is hum in the transformer that is resinating through to the speakers. At first I thought it was bad filter caps but when i scoped their and also checked the AC voltage at each cap I found it to be less than 0.89VAC which should be acceptable...
The only time the low harmonic ham changes is if i press the mute button, adjust the tones and turn the volume up so the music drowns it out. When the mute is pressed the sound completely is eliminated.
I took the jumpers off the amp out to in, hooked up a bluetooth device to the in and there was no hum. I do not recall if the transformer also stopped humming but I can check that again tomorrow.
The sound reminds me of the sound cheap rca cables make when hooking a phono to an amp but with just a little more buzz.
I am not convinced the problem is the transformer itself, i think there is a load causing the hum. Any suggestions on where the issue may be hiding?
Thanks, James