Tascam us2x2 headphones knob problem (volume)

[Ronx]

I bought tascam us 2x2 audio interface and I got a problem with volume knob for headphones output. So whenever I'm turning it to play louder (tweaking it to the right) and I cross a point of about 70% from this point the volume gets lower and lower. It's a noticeable change of about a few dB I guess.

My headphones are hyperx cloud that I believe have 60 ohm impedance.

Have anyone had similar issues with audio headphones out in some audio interface/other device? What could be the issue here?

 

[dave9]

This is old gear you bought used I presume? Maybe dried out grease on the portion of the pot travel seldom used.

You could use a multimeter on the pot pins to determine if the resistance between the wiper and either end of the conductive element varies as it should with rotation of the knob. It does not need to be, nor should it be powered on while doing this. In-circuit, you may have other resistors affecting the reading but should still see a change in resistance that doesn't go the other direction when you hit that ~70% point.

If that's the problem, try spraying some electronics contact cleaner in the pot while rotating it full travel. You could also try rotating the pot through this region many, many more times without cleaner to see if it wears through grease or any oxidation/gunk/etc.

If it's a sealed pot you could try to disassemble it or replace it, though in some cases you might have some luck heating it with a hair dryer to soften grease, or a hot air gun at a safe distance. If it can be disassembled, wipe off the conductive traces with a slightly abrasive dry paper towel, check the wiper contact points for oxidation and polish them clean if needed, and in many designs you can slightly bend a little more spring tension into the wiper arms as they can weaken over years.

 

[Ronx]

It's new, not used before. Maybe just I was unlucky with this one unit.

I'll try some of the things you mentioned. Thanks a lot!