I just took apart my Aguilar TH350 amp for its annual cleaning where I blow it out with compressed air and clean all the pots and jacks with DeOxit. I noticed what looks like an internal variable resistor on the preamp circuit board, see attached pic. Is this some kind of a trim pot and if so what does it control?
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Aguilar Tone Hammer Internal Trim Pot?
- Thread starter PolkaHero
- Start date
Is the amp working as it should? If so leave it alone and don't try to fix what ain't bust! 
Be very careful with compressed air. If used carelessly you can blow stuff right off the board.
Be very careful with compressed air. If used carelessly you can blow stuff right off the board.
Is the amp working as it should? If so leave it alone and don't try to fix what ain't bust!
Be very careful with compressed air. If used carelessly you can blow stuff right off the board.
Works great, just curious.
You know what curiosity did don't you? 
It's no longer under warranty. You mean none of you guys take apart your computers and other electronic equipment and blow the dust out at least once a year? I don't bother with my amps that have dust covers but this one sits out in the open most of the time. You would be surprised how much dust accumulates inside!
I can't find a schematic online nor do they provide one in the manual. I bet they won't tell me what it's for but I can try asking!
I don't have the schematic. Maybe the pot is for setting a bias.
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'til the experts comes along with the difinitive answer, my WAG is that it's some kind of a bias pot.
Or it may be used to set the amp's overload protection trip point.
In any case, it's not there to dink with.
"No user serviceable parts inside." Ya know?
If they wanted you to turn it they would have put a knob on it and stuck it through the front panel.
But nice that you gently clean the innards regularly.
Or it may be used to set the amp's overload protection trip point.
In any case, it's not there to dink with.
"No user serviceable parts inside." Ya know?
If they wanted you to turn it they would have put a knob on it and stuck it through the front panel.
But nice that you gently clean the innards regularly.
It got me into some "places"You know what curiosity did don't you?
drool I probably would not have gotten into without the curiosity. drool 
That pot is on the preamp board. Probably not power amp bias related (how are Class D amps biased, anyway?).
I do clean the cooling paths of my amplifiers but do it with a vacuum and wearing a face mask. The fans in the amps can suck up all sorts of crud some of which will not be good for you. Blowing it out puts all that stuff back into the air to be taken in by your lungs.
I couldn't see that the pot was in the preamp.
"Biasing" in class D is different, more related to balancing and efficiency.
Even the basics are complicated:
http://www.infineon.com/dgdl/an-1071.pdf?fileId=5546d462533600a40153559538eb0ff1
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Yeah, without having seen one opened up (or, own one) given how tight that photo, above, this should help.
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You know what curiosity did don't you?
Yes, curiosity pretty much gave birth to all great inventions and discoveries, including music in all it's forms.
1) Have a few beers.
2) Turn on amp and start playing.
3) Hand the screwdriver to a buddy....preferably one who has also had a few.
4) Tell him to turn that sucker back and forth so we can all find out what it does.
5) Ignore 1-4..... and that trim pot.
2) Turn on amp and start playing.
3) Hand the screwdriver to a buddy....preferably one who has also had a few.
4) Tell him to turn that sucker back and forth so we can all find out what it does.
5) Ignore 1-4..... and that trim pot.
