Recommend a spray for scratchy power amp pot

[m.oreilly]

my qsc rmx 4050hd has had an odd issue with the left side volume knob for quite some time, but has gotten progressively worse. at start up, the output will be super low at times, and turning the knob back and forth will give a scratchy sound during traverse, but as it is put to 36, and i let go of it, the output again drops, and now it will drop while i'm in the middle of playing. i'm hoping the volume pot is just dirty, but the output drop worries me...

[allexcosta]

DeoxIT

[craig.p]

> i'm hoping the volume pot is just dirty, but the output drop worries me...

Relax. That symptom is consistent with a dirty gain pot.

[Fekwood]

DeoxIT
Might seem a bit expensive for a little can, but it has worked wonders for me! Better than the 'Tune-A-Wash' stuff I used years ago.

[abarson]

Deoxit can be found at Fry's, but it doesn't look like there's one near Ukiah. You might want to call around places like Next Wave Electronics, but there are plenty of places to purchase it online. It might be available at your local Radio Shack. Don't waste your time or money on alternatives. From my experience, the Caig's products are best.

[Foz]

radio shack carries Caig products including deoxit - call your local store to see if its in stock

when you get some tip the amp on its ass so the knobs are facing up - remove knobs and liberally apply to the shafts - leave sit over night - re-apply to shafts and twist the knobs from max to min several dozen times.

if that doesn't work time for the lid to come off - use a tech if unskilled - you could hurt yourself poking around inside an amp without some basic safety knowledge.

good luck

[m.oreilly]

thanks everyone. i'll hunt up some deoxit

[m.oreilly]

in stock about 4 blocks away. thanks again

[Zooberwerx]

Just got done cleaning the guts of an RMX 1450...same symptoms. I used Lawson's Electrical PowrOff Contact Cleaner because I was able to swipe a can from work. While you're in the chassis, it's a perfect opportunity to clean the dust out, particularly around the fan, housing, and heat sinks.

Riis

[BassmanPaul]

Originally Posted by Zooberwerx

I used Lawson's Electrical PowrOff Contact Cleaner because I was able to swipe a can from work.
Riis

Naughty naughty Riis. Didn't you mean "borrowed"?

[vin*tone]

Originally Posted by Zooberwerx

Just got done cleaning the guts of an RMX 1450...same symptoms. I used Lawson's Electrical PowrOff Contact Cleaner because I was able to swipe a can from work. While you're in the chassis, it's a perfect opportunity to clean the dust out, particularly around the fan, housing, and heat sinks.

Riis

Some cleaners don't lubricate which you need in a pot. Karma might bite you on the ass.

[Bob Lee (QSC)]

Caig FaderLube both cleans and lubricates, which is what you want in a pot.

Then, the trick is to get the spray into the pot and not just on it. If you can, bend the end of the straw into a J shape, and spray it generously into the opening that faces the circuit board. Then work the pot back and forth, end to end, to spread the cleaner/lube across the resistive element.

[Interceptor]

I've been using the Caig stuff for years. Fader stuff is the right stuff for a pot.

But, it isn't always the answer. Replacement of the pot is then called for.

They're not at all expensive.

[craig.p]

Originally Posted by Fekwood

DeoxIT
Might seem a bit expensive for a little can, but it has worked wonders for me! Better than the 'Tune-A-Wash' stuff I used years ago.

Yeah, that "wash" stuff will eventually take out your pots long-term, unless you follow it with a lube product after it dries. We used to call it Agent Orange in tech school, and hardly ever used it.

[Zooberwerx]

Originally Posted by vin*tone

Some cleaners don't lubricate which you need in a pot. Karma might bite you on the ass.

Did I mention it was free? I've read that repeated over-application with certain solvents will strip the lubricant and should be avoided. I made the compromise as I, quite literally, never adjust the attenuators on the power amp save for the initial gain structure set-up....seriously.

Riis

[Bob Lee (QSC)]

Gain control pots (and other controls) should always have decent amounts of lube inside (IOW, don't use a non-lube cleaner), and you should periodically work them back and forth to break up dust and other contaminants that might get in and cause the pots to be scratchy, intermittent, etc.