[Talonz]

Hi, I was finishing my mint amp today, and after putting it in the case, both channels worked great, but I still had to install the LED. After doing this (I took the board back out), the right channel no longer works. When both channels are balanced, the right channel is very very weak.
Attempting to raise the right channel volume on the computer results in massive distortion. Muting the right channel results in regular volume in the left channel and none in the right. Muting the left channel results in both channels acting like the right channel in mono with the low volume and distortion. Could it be that I blew out the buffer? I checked my wiring and for shorts, and no problems were found. Input voltages are standard, so it's somewhere within the amp. Is there any way to test to see if it was the buffer without taking it out?

Many thanks!

 

[gsferrari]

Dont imply noobiness but did you insulate the board after soldering before installing into the case? is this a MINT case? Is the opamp loose? all connections OK?

Check ground connections on headphone output, amplifier input and volume controls. Check these "out of board" connections first before doing a visual on the board.

Distorted sound sounds like a loose ground....poor solder flow somewhere...a dry joint.

Cheers!

 

[Talonz]

It's insulated between the two boards and does the same thing when lifted out of the case. All solder joints look solid, I'll check on the grounds and report back. In the meantime, any other suggestions? Thanks

 

[Talonz]

More information:

When right output is grounded, right output is silent (as expected).

When left output is grounded, faint noise and distortion is still there (unexpected).

 

[Megaptera]

I think the two places you're most likely to find the problem here are the volume pot and the connections between the two boards. I would use a meter to check for shorts between the pot's pins (there might be a short underneath the pot, or some conductive shmutz under the flux, or who knows what else you can't see), and triple-check there's no shorts, bad joints, or miswiring on the connections.

 

[tangent]

Quote:

It's insulated between the two boards

Insulated with what?

 

[Talonz]

Teflon

 

[tangent]

Then it probably isn't a short between the boards. It's common to see that when people use electrical tape, which isn't tough enough to put up with lead stubble grinding into it.

Have you followed the steps here: http://tangentsoft.net/audio/trouble.html ?

 

[Talonz]

Thanks for everyone's help!

I finally found the solution, which was that I blew out one of the drivers on my cheap test headphones. Glad I read the advice not to use a good pair to test!