Crate TX50 DB has noisy DSP circuit when rotating the DSP pot!

Try with a on/off footswitch Wrong cable, or bad PCB connection switch on main tone board.

Check Battery

If you have already spray cleaned the pots and switches then the problem is almost surely bad solder connections on the board. This happens often if unit travels a lot with no case. Resolder all pots, switches and jacks and check copper trace for breakage at these places. In case of broken trace hard wire across breakage.

Contact Crate for the best info.
http://www.crateamps.com/support/index.php

Hi there,I have the same problem with my flexwave 120. I opened the amp to measure several capacitors on the small effect circuit board. If one of this capaciters have internal short circuit, wich will effect the others causing effects to fail. I removed them one by one to find possible short circuit. All capacitors were ok. I think the problem is in the processor wich is to diffucult to replace. I think it's easier to replace the effects circuit board. But where do we find this board??

Yes, the pots are replaceable. Removing them from the circuit board requires solder removal tools. DO NOT atttempt to remove these with solder wick. The new high temp solder (ROHS) will surely cause the board to be damaged. I use an Ungar powered solder removal system. The parts can be found at DigiKey.com or Mouser.com. The part value is marked as is the taper which will likely be an "A" or "B" suffix. Search for potentiometer, slide. You have to exactly match the circuit board pin layout. The distributors have links to the manufacturer's spec sheets to compare. First thing is to measure the travel, then find ones with the right mounting, then the resistance and finally the taper suffix. The parts are typically between $1.50 and $3 each.

This has a digital reverb unit. The settings are subject to get clobbered I suspect. I don't know if you are using foot switch for the reveb control... You may also have a cable that has come loose...

Here is a link to schematic for your unit:

http://elektrotanya.com/crate_flexwave_guitar_amp.pdf.pdf/download.html

Notice that the reverb is set by DC voltages from teh setting pots that go to the DSP chip. These setting pots receive voltage from a 16 volt ZENER regulated source. First thing is to CHECK that voltage. If the Zener has opened and you find much over that 16 volts, that is your cause of the problem.

The circuitry is on page 1 in the 3B to 3D lower left of the page.

Witth an oscilloscope analyze the ripple voltage across C67, C70, C14, and C12. Pay close attention to the last two of these which are on +/- 15 volt lines.

The "chirp" when shutting down is LIKELY normal and would probably be from teh DSP effects unit as it goes down. The voltages go out of the operating range and the device essentially goes nuts for a second or so.

NEVER use switch cleaner such as DeOxit on pots !!!!!

I have used CRC226 available at Home Depot electrical dept.

I SUSPECT that the resistance element in that pot is cracked. This is common if the knob sustained a hit. Replacing the pot is the only cure if the element is cracked.

Reviewing the schematic, ALL audio passes through the wiper on the HIGH tone pots. If the wiper is intermittent, so will be the sound.

If your unit is solid state amp, the pot looks like a 10K ohm LINEAR taper.
If you have a tube type, then the pot is a 250K ohm LINEAR.

Note that the other tone pots in the units are AUDIO tapers, but the high is a linear taper.

Get repair parts from either DigiKey.com or Mouser.com

An educated guess is that you have a cracked circuit board or a bad solder joint. OFTEN the boards crack or traces get lifted or solder broken near pots such as volume control, etc.

Another place to look is the connections where jacks are soldered... those are chronic failure points.

One other problem is the bypass switches on the effect insert jacks. The contacts of the switch part of the jack get oxidized or bent.