Hi folks! I have this amplifier that had a high dc offset on one channel at first startup, about 75mv, so i replaced the AN7062 and that seemed to correct the problem because the inmediate result was over 4-5mv on the faulty channel.
On the tests about two hours later i heard a slight hissing sound through the speakers so i stopped the music, set vol to min, no input and measure dc again, was like 67mv on the same problematic channel, then all of a sudden it corrects itself to 5mv, a few seconds after jumps again to 70mv.
Power off, wait a few seconds power on again and starts at 5mv and about one minute later... again... 70 - 80 - 65 - 75 etc. again all of a sudden back to 5mv...
I have a video of the problem
YouTube
Can the AN7062 be the culprit again?
What else i have to look for?
I will appreciate some light in here
See ya!
On the tests about two hours later i heard a slight hissing sound through the speakers so i stopped the music, set vol to min, no input and measure dc again, was like 67mv on the same problematic channel, then all of a sudden it corrects itself to 5mv, a few seconds after jumps again to 70mv.
Power off, wait a few seconds power on again and starts at 5mv and about one minute later... again... 70 - 80 - 65 - 75 etc. again all of a sudden back to 5mv...
I have a video of the problem
YouTube
Can the AN7062 be the culprit again?
What else i have to look for?
I will appreciate some light in here
See ya!
Try freeze spray on AN7062 - if change occurs, it will be the offender
Check Q502 and Q504 for dry joints.... if freeze spray had no impact w/ 7062 try freeze spray on these.
Check Q502 and Q504 for dry joints.... if freeze spray had no impact w/ 7062 try freeze spray on these.
Have you checked for oscillation on the output when the bias is high ?
That would cause an increase in current.
That would cause an increase in current.
Thanks for answer! Previously resoldered those and most of the pcb, also for the record this amp comes with "factory upgraded"?? A1124s C2632s but i will check with freeze spray
Hi! Nope, i didnt check that, and i dont know the bias value (where can i find this value? It seems no adjustment possible here), just dc offset
Bias is manipulated by Q501 and 502 (controlled by ICQ Controller) inside SVI is main bias circuit, and in its output stage Synchro Bias.
Haven’t had oscillating issues in a V4X - and would be surprised if that was an issue.
I have seen intermittent / open Q503 and 504 cause whistling /distortion in sound.
Haven’t had oscillating issues in a V4X - and would be surprised if that was an issue.
I have seen intermittent / open Q503 and 504 cause whistling /distortion in sound.
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