Blue bank has a led that is bad when using the lights for more than 30 minutes the blue color goes out. i open the unit and just touch the blue led pack in the back on the solder led part and they turn on again....

Check Connections or Fuse !

Check the burned out LEDS with a 3 volt battery- a computer bios battery works well for these.

If they do not light, which is likely, just replace them with similar sized units. You can even change their color too. Measure the voltage at the LED sodler pads to see if it is more than 3 volts, if it is, add a resistor to drop the voltage and limit current to the replacements. Digikey sells them, and they ship around the world http://www.digikey.com or Mouser, Both are based in the US, I am not sure what Mouser's international shipping is. http://www.mouser.com

If there is no voltage at the LED pads, look for bad solder connections, or burned out resistors. If the few remaining LEDs still operate as they should, the level meter chip "should" be okay.

First thing to ty is to try it using two 9 volt batteries as a test to see if lights work.

I ASSUME that you are NOT trying to use the pedal in the external effects loop (send and return) as the levels are not compatible. The pedal must be between the guitar and the inout of the amp.

Beyond this I would open the unit and look for something loose or broken where the blue LED is located.

We can only guess at the cause without tearing into the unit. My educated guess is that either the cable to the color step motor has either come loose or a wire is broken in the cable. SInce the wires go through a flexure point, that MIGHT be where the problem is... the only way to tell is to do detailed troubleshooting of the unit.

Before jumping to conclusions, one should do some testing. It is posssible that you are having a DMX data error. If your lines are long, please review the need for a termination resistor at the far end of a DMX chain. The reflections of the data pulses can confuse or cause errors. Test a unit up close to your controller so the cable is short. If that magically works, install a terminating resistor.

Beyond this, electronic testing needs to be done. I did find in a Chauvet LX5 a bad solder joint at a connector that brings the power for, in my case, the green LED's. There will be surface mounted resistors on the back of the board that limit the current to groups of LED's.

If the whole fixture loses the blue at once, either suspect a DMX error or the driver in the fixture.

Since the PA clip is not lit, the problem seems to be up front...

First thing is to look for a bad cable as a broken ground could be putting hum at a clipping level. First thing, test this by unplugging all inputs. If the clipping light goes out, then you have bad cables or a ground loop.

Try sending a line level signal into "Effects return" to test if the power amps are OK.

If the clip light is still on, turn all gain controls down to minimum. If light is still on then take unit for servicing.

Try as you might, there doesn't seem to be a contrast control on this unit.

Things to try:

Shielding from light.

Polarizer similar to those used for privacy on computer screens.

Try a color filter, possibly orange.

Maybe a good old umbrella as silly as it sounds... there just isn't any way to darken the display.

The display by the way is NOT and LED, but a LCD on this unit.

The circuitry is a bit complex for that PFL light. The LED is driven by a transistor T38 type BC846 to turn it OFF by grounding out the current coming by way of teh MUTE LED or the MUTE switch (SW14) horts out the MUTE LED. There is a 1K limiting resistor from +15 volts feeding the two LEDS in series.

IF transistor T38 is open the PFL will be on. HOWEVER T38 will also be turned off if transistor T44 (BC846 type NPN) or if capcitor C90 2ufd/50v is shorted OR if resistor R253 is open OR is switch SW8 (PFL DPST )is not contacting the ground side of of the half tied to R247. If R247 is open that will also cause the PFL LED to illuminate...

AND if the signal coming in is at clippling level the PFL LED will light.

All that circuitry serves as a clip detector plus the PFL function.

Verify you are not sending clipping level into the channel first... turn the trim off. If not, you are in for major surgery as all the knobs for that section of the circuit board and the screws for the XLR's and the 1/4 inch jacks must come off as well as some support screws IF it is necessary to access the top side of the board... Maybe you will get lucky and the bad component MIGHT be on the bottom of the board.

I want you to do a test. while using the amp plug a pair of headphones into the preamp out... note you will only hear stuff on one side if they are stereo phones and the sound may be fairly weak... while the unit is operating correctely then unplug phones and use it. When it fades out plug in phones compare the level when it was OK... If the preamp output fades lower as well, then we know problem is in the preamp section...

We can do a lot of troubleshooting without opening the amp.

I see nothing in the scheamtics that should be an issue causing this...

Since it didn't fail for the tech, think "what was different?". Are you connecting something else? Foot pedal? Temperature? :Loudness of playing?

Now what else is in common to these two units... AHA! The guitar...

If your guitar has a battery in it, the 20 to 30 minutes fading would correspond to a battery failing and then recovering after you unplug the guitar for a while.

There may be an internal fuse, but the unit will need to be serviced by an electronics shop.

If no odor or burning smell happened, then I suspect a bad solder joint or cracked circuit board. Look the board over with a very bright light.

LOOK for a dark circle around pins of HEAVEY components in the solder menicus for all the pins of the heavy components.

Look for board cracks with a small LED flashlight shined through the board.