G'day,
I've got a S/S headphone amp that has an intermittent noise on one channel. It's very infrequent - maybe once every few hours. Sometimes it happens not long after powering the amp, other times it happens after some use.
The amp is an open loop, opamp feeding a diamond buffer.
For reference, I've attached the schematic.
I've tried replacing the opamp, cleaning the Alps pot, checking the PCB for dirt, and ran THD tests. I've stopped using it because I'm worried it's going to damage my headphones.
I've got a S/S headphone amp that has an intermittent noise on one channel. It's very infrequent - maybe once every few hours. Sometimes it happens not long after powering the amp, other times it happens after some use.
The amp is an open loop, opamp feeding a diamond buffer.
For reference, I've attached the schematic.
I've tried replacing the opamp, cleaning the Alps pot, checking the PCB for dirt, and ran THD tests. I've stopped using it because I'm worried it's going to damage my headphones.
Attachments
You may have to wait until it becomes more frequent to make finding it easier.
Hook up some junk speakers through a resistor and poke around on everything with an insulated tool,
to see if you can make the noise happen.
Hook up some junk speakers through a resistor and poke around on everything with an insulated tool,
to see if you can make the noise happen.
Only one channel does it.
When it happens, it sounds like a "shhh" sound followed by a blip.
It sounds a bit like DC you get when turning an old potentiometer, but louder and consistently. I have to power off the amp to stop the noise (and potential damage to the driver)
Could it be a faulty transistor? Or failing capacitor?
I'm not great with troubleshooting
You may find heat or cold (freeze spray) may trigger the symptoms. Do small areas at a time. Work around the board in a methodical manner.
Applying pressure around the board with a spudger is another useful tool for finding intermittent faults.
Applying pressure around the board with a spudger is another useful tool for finding intermittent faults.