Film-Tech Forum ARCHIVE: QSC RMX amps static when changing gain

This is topic QSC RMX amps static when changing gain in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Mike Frese (Member # 4361) on 03-07-2013, 07:03 PM:

I have a couple of RMX 850s that emit a bit of static for a brief moment when the gain control is changed. Sometimes the sound sounds muffled until I change the knob a tad. Once set, they work fine.

Should I be concerned?

Posted by Tony Bandiera Jr (Member # 2365) on 03-07-2013, 10:33 PM:

Mike, it most likely means the gain pots are dirty. Often a good temp fix is to rapidly turn them back and forth to each extreme several times.

If that doesn't clear them up, QSC's service department is not only fast but also very reasonably priced to fix such a problem. (If you are handy with a soldering iron you can change them yourself, and QSC sells the parts.) The advantage to sending the amps to QSC is that they will go through them fully and make sure all is ok. (They may even do it under warranty depending on the age of the amps and what is wrong.) The standard warranty is three years, but QSC has repaired older ones for me at no charge (including my 8 year old C-stock DCA 1644). Go to QSC's website LINKY and select "Shop QSC" and "QSC Parts and Accessories" from the drop-down menu. Service info can be found under "Support"

Looking at the site, for your model the pots are here: POTS at $2.35 each......or replace the whole right channel module with the pots MODULE for $139.99

Since the amps are modular should be very easy to just replace the pots actually.

Posted by Mike Frese (Member # 4361) on 03-08-2013, 01:22 PM:

Thanks Tony. That worked well.

Posted by Dave Macaulay (Member # 813) on 03-08-2013, 03:27 PM:

Just shooting some isopropyl into the pot (it's far from sealed) and cranking it between stops while wet will usually clean them up but that's not as good as new pots.

Posted by Louis Bornwasser (Member # 3063) on 03-08-2013, 05:00 PM:

WD40 has always been the very best cleaner. Even better than purpose-made cleaners like Quietrol. Louis

Posted by Tony Bandiera Jr (Member # 2365) on 04-04-2013, 08:09 PM:

Mike: Glad I could help you out. [Smile]

Louis: Yes WD40 works very well for pots..just gotta be careful to not let it get on any power resistors or other high-heat parts...it really makes a stink. [Big Grin]