Popping and Scratching with Emotiva BPA-1

[kaz]

I have an Emotiva BPA-1 stereo amp hooked up to my computer via line out and it runs a couple of speakers on my desk. If I have the volume knob turned down to zero and then increase it, the amp makes loud pops and scratches until the audio can be heard, then it works fine. No idea why this is happening, but it's very loud and annoying.   I tried a different source (iPhone) and it does the same thing.

I took it apart to see if I could see anything obvious, possibly clean the volume control knob.  It's basically a sealed unit, so not much I can do.  

Any ideas?

[novisnick]

Obviously it old vinyl!!    


 
Good luck with your problem, sorry I can't contribute to a solution.

[garbulky]

It's likely dust. Turn it up and down a few times. Hopefully that'll dislodge things.

[eclypse]

Knob should pull straight off one would think. Get thst off and see if maybe you can use a can of air to blast it clean or something.

[kaz]

I tried pulling off the knob using enough force that if the knob was supposed to come off it would have. Didn't budge and I don't want to go all Hulk on it. Even if the knob did pull off, it would just be the big shiny round part and the post would still be there, not giving me much of an advantage. The unit looks sealed, so not sure air would really get in there.

[tchaik]

there should be contact cleaner available that can be sprayed into the volume unit that should clean it up and reduce the noise. check amazon.

tchaik………

[Jim]

Looks like there is an opening in the potentiometer (mounted on the board)

Maybe try some Deoxit:

[Deleted]

Yup! That's the stuff!!

[kaz]

Yes, there is an opening, I'll give it a shot.

Thanks!

Apr 29, 2016 12:21:21 GMT -5 Jim said:

Looks like there is an opening in the potentiometer (mounted on the board)

Maybe try some Deoxit:

[leonski]

Radio Shack USED to sell a well regarded contact cleaner. I use the DEOXIT on my Annual stereo PM, when I take everything apart, clean it all, and redo virtually ALL the connections.

Vol Controls have what are supposed to be 'Self Cleaning' contacts.

Run it UP / DOWN several times. THAT might help. See link for a radio shack product that might do the trick.

Do NOT use canned air. I don't know WHAT'S in it, but it leaves a film.

www.radioshack.com/collections/maker-parts-kits/products/precision-electronics-cleaner?variant=5717905605

[Jim]

Apr 29, 2016 14:35:17 GMT -5 leonski said:

Do NOT use canned air. I don't know WHAT'S in it, but it leaves a film.

It's probably the bitterant that they add (Because huffing air cans used to be cool). Can leave a powdered residue, at least.

You could use compressed air (like from a compressor)....... anything that lacks the gross bitterant.

[leonski]

When I worked semicondutor manufacturing we had a huge pressure vessel in the facilities area which held LIQUID NITROGEN. This was gassified and used for various things in the plant.
The 2 MAIN uses were for 'air actuated' valves and for some blow off guns, little valved air nozzles. NO OIL in LN2 and even sub-micron particles were filtered out, in-line.

Little or NO compressed air used in a clean room, since it INVARIABLY picks up OIL from the compressor. Sure, there are oil seperators, but we're talkin' MICROSCOPIC amounts. In any event,
I don't want any of THAT or Bitterant (what ever THAT really is) in any of my electronics. Are their DRY compressors?

If you DO use compressed air, keep the pressure LOW and install a oil seperator and use a POINT OF USE filter on the tip of your air nozzle. For home use, 10 microns shouldn't be TOO restrictive
and will trap any residual oil.