madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: tenwatt on April 01, 2013, 03:05:12 AM

Title: Tough to Turn Pot
Post by: tenwatt on April 01, 2013, 03:05:12 AM
I have a pot (that I didn't try to turn before soldering into place) that is very tough to turn and, at certain points, it takes shear force to turn past those points BUT, despite it's difficult to rotate, the pot still does it's function perfectly.  It has a great sweep.  Is there a way to fix this or is it just a remove and replace?
Title: Re: Tough to Turn Pot
Post by: jprizz on April 01, 2013, 03:39:37 AM
Do you have a knob on it? Sometimes I have knobs with a burr that rubs underneath it that causes some binding, just raising the knob up a hair takes care of the problem.
Title: Re: Tough to Turn Pot
Post by: JakeFuzz on April 01, 2013, 06:21:23 AM
Josh brings up a very good point about the knobs. That has happened to me many times.

The other issue I have seen with rough patches in the pot rotation is if you put too much solder down on the middle lug the solder can rub against the metal wiper causing excess friction. I have had this happen with a few pots. I would check the middle and outer lugs as they go into the pot casing. If they are rubbing I usually heat them up with the iron and blow on them hard to get the solder off.
Title: Re: Tough to Turn Pot
Post by: tenwatt on April 01, 2013, 12:07:57 PM
It's not the knob.  It did this before a knob was on the pot.

I don't think it would be the solder issue since these are board mounted pots but I'll check that.
Title: Re: Tough to Turn Pot
Post by: rodstewart on April 01, 2013, 01:41:11 PM
This is obviously something you have to be careful with, but I found, accidentally, that slightly heating the pot can greatly smooth it's rotation.

I'm guessing this is due to the lubricant heating and redistributing. It's probably also a great way to destroy your pot though.
Title: Re: Tough to Turn Pot
Post by: stecykmi on April 01, 2013, 08:33:20 PM
pot are surprisingly durable when it comes to heat, people often use them as grounding posts by soldering to the back casing. since they act as fairly good heat sinks, it takes quiet a long time to heat them up enough.
Title: Re: Tough to Turn Pot
Post by: madbean on April 02, 2013, 12:36:32 AM
This will make all those husky Alpha pots like gold: hit the inside with contact cleaner and rotate it back and forth about 25 times. It will loosen up a whole bunch.
Title: Re: Tough to Turn Pot
Post by: slimtriggers on April 02, 2013, 03:45:09 AM
I've had ones that didn't line up with the hole in the enclosure just right.  The slight angle after tightening it was enough to bind it up.  I'm talking a relatively slight angle, too, not a leaning tower kinda thing.  I now drill the holes out one step bigger to help with alignment-especially with board mounted pots.
Title: Re: Tough to Turn Pot
Post by: hammerheadmusicman on April 02, 2013, 08:19:58 AM
Deoxit is magic contact cleaner! it deposits some lubricant as well as cleaning, bit pricey but very good!
Title: Re: Tough to Turn Pot
Post by: marmaliser on April 02, 2013, 08:27:09 AM
Quote from: slimtriggers on April 02, 2013, 03:45:09 AM
I've had ones that didn't line up with the hole in the enclosure just right.  The slight angle after tightening it was enough to bind it up.  I'm talking a relatively slight angle, too, not a leaning tower kinda thing.  I now drill the holes out one step bigger to help with alignment-especially with board mounted pots.
I have had this recently also.  Its easy to check if this is the problem, just back the nut off a couple of turns
Title: Re: Tough to Turn Pot
Post by: tenwatt on April 02, 2013, 12:14:41 PM
Quote from: slimtriggers on April 02, 2013, 03:45:09 AM
I've had ones that didn't line up with the hole in the enclosure just right.  The slight angle after tightening it was enough to bind it up.  I'm talking a relatively slight angle, too, not a leaning tower kinda thing.  I now drill the holes out one step bigger to help with alignment-especially with board mounted pots.

DING!  DING!  DING!

I removed it from the enclosure and it wasn't bound up any more.  First time I've experienced this one.  I was able to straighten the board mounted pot and reinstall it and it works like a charm.  I had to push the little tabs that hold the shaft into place.  It was in such a bind that it loosened them.
Title: Re: Tough to Turn Pot
Post by: pickdropper on April 02, 2013, 02:21:37 PM
Quote from: stecykmi on April 01, 2013, 08:33:20 PM
pot are surprisingly durable when it comes to heat, people often use them as grounding posts by soldering to the back casing. since they act as fairly good heat sinks, it takes quiet a long time to heat them up enough.

Yeah, they are pretty tough little buggers.

I recently found out their limits when I ground down the shaft of a 9mm pot for one of my 1590a builds.  I don't know if it was heat because I went to fast or the vibration on the grinding wheel, but I managed to kill it.
Title: Re: Tough to Turn Pot
Post by: 12345 on April 02, 2013, 04:57:19 PM
i've doen that before! Put it in the fridge to cool and its normally right as rain!