I was adjusting up the bias (variable resistor at R113) on my Aleph 3 clone and found something odd. On one channel I was able to adjust the voltage to .500V across all 4 resistors R120-R123. When I adjusted the other side I found that when R120 and R121 are at .500V, R122 and R123 ar at .400V. They're always about .1V lower. I've checked resistors and compared them from side to side, but I haven't seen anything alarming. What could cause this imbalance?
Attachments
if amp is functional , without burned parts and wiring mistake , that can't be ......
simply - current path trough upper source resistors is going to and through lower source resistors
difference of 100mV across each of them is counting for 200mA of current difference and it can be produced from nowhere and can't go anywhere
except in case that you have load connected , when 200mA through 8R speaker will result in output offset of around 1V6
btw. there is possibility that some (lower one ?) of these resistor endured some abuse and they're partially damaged , increasing resistance
but two of them , having same defect ........ and still functional ......... ??
replace them
simply - current path trough upper source resistors is going to and through lower source resistors
difference of 100mV across each of them is counting for 200mA of current difference and it can be produced from nowhere and can't go anywhere
except in case that you have load connected , when 200mA through 8R speaker will result in output offset of around 1V6
btw. there is possibility that some (lower one ?) of these resistor endured some abuse and they're partially damaged , increasing resistance
but two of them , having same defect ........ and still functional ......... ??
replace them
Last edited:
I checked the source resistors in question and found each of them to be about .1ohm less than the other side. That would put the voltage at about what I'm seeing. I removed one and it has a slight discoloration on it. . I'm going to order some up tomorrow. Thank you for the help!
- Status
- Not open for further replies.