When i plug an MXR micro amp (volume boost) in front of the supersonic, it works on the clean channel but does not affect the burn channel, Why? By the way, when plug in to the effect loop it does work well. But my configuration does not allow me to put the pedal there....

Check the pots in the affected channel for clean wipers. You can squirt chemical cleaners into them or you can remove all power and go to the controls and go back and forth from one extreme to the other and virtually wipe the surface clean via friction. If that and checking connections does not do the trick you will have to resign yourself to the fact that you have a loss of gain in the affected amp and you will have to inject a signal and resort to signal tracing to locate the culprit.

I would get a can of good electrical contact cleaner and open the unit, spray the cleaner into the back of the controls while rotating them back and forth quickly. This will somewhat clean the control contacts inside eliminating most dust and corrosion. If the control is too old and dirty, it may not work but, I would definitely try. It probably has a special made potentiometer that would be hard to find and replace. They usually have special legs attaching them to the board. I am almost positive that the control is bad or dirty, though. If the sound gets loud when almost all the way up, it does indeed work, just not in a dirty position. That already proves it.

Usually with volume pots,the ratings dont matter. you can really buy then anywhere like guitar center,micro center and online. they're really cheap and well worth it.

This is because your clean channel only runs through the pre-amp section, requiring an increased volume level to match that of the volume of the drive section which is overdriven by the pre-amp circuit. my suggestion is to use lower volume level on the clean channel of the amp. To get any volume boost you may need to match the two channels you could use a signal/volume booster or overdrive pedal between your guitar and amp input, switching it off and back on when you switch back and forth between channels.

It could be a couple issues in that section. Start by cleaning the contacts and switches to make sure it is not dirt. Also check to make sure the plug you are using is right for the jack- just to make sure everything is connecting as it should and nothing is inadvertantly getting shorted- such a 2 pole plug plugged into a 3 pole jack.

If those are all okay, the issue is in that boost channel section. Check to see if you are getting both power rails at the IC's, measure on a 4558 chip pin 4 to chassis should be -15 volts and pin 8 should be +15 volts to chassis. if you do not have this voltage, check the wiring, check the PC board for bad solder joints and check capacitors. Also check the physically larger resistors.

If you have the voltages, put an audio source on the input and set up a headphone with test leads, or better- an impedance matching transformer with test leads on the high impedance winding- put one to ground, with the other lead, move from IC to IC to locate the area to look at. You can get a data sheet for the 4558 here: http://www.ti.com/lit/ds/symlink/rc4558.pdf It is a low noise version of the 1458 family of op-amps. Check each IC at the inputs and the output, once you locate the stage where inputs are clear and output is garbled, that IC may be the fault, or something in the vicinity- usually it will be the IC. You can get any configuration of the 4558 you need through Mouser or Digikey, and Digikey does ship worldwide http://www.digikey.com

Once you get the new IC in, you should be groovin in no time.

It just doesn't have enough power for what you want. Either get a bigger version amp OR mic it and run it into the PA system where hopefully you have enough power.

First thing to test: Do all the controls vary their function smoothly or does say the volume control vary the output only slightly. If the latter condition exists I would open the pedal and look for broken solder around one lead of the volume pot. The broken solder is hard to see... look for a little grey line on the menicus of the solder filet around each lead. Also look for cracks in the circuit board. Use a bright light.

DO NOT run amps into clipping. Also, while the speakers are rated at 600 Watts, you don't want to use an amp that delivers that much RMS. Use about 300 Watts per side. Unfortunately you did not mention the brand of amps you are using. I will also caution you that the speakers have protection networks that if you are getting supersonic feedback that you can't hear that can burn out the amps. DO NOT boost the highs if the mics can "hear" the speakers or the reverberations from them. Solid connection of speaker cables is important. Intermittent connections can fry amplifiers... I won't go into the technical reason for this other than to say the amp's feedback circutis get confused when the load shifts.

You might also have the speakers checked since they can have an intermittent that is popping the amps. If you happen to be using BERHINGER PMP amps, please read my tip about the grounding hazard where the sleeve of channel A is hot and the tip the cold that I have in the Fixya tips.

initially you want to think bad solder joint, but it think its a bad mosfet or rectifier or diode. it would be hard for an untrained person to identify your problem let alone an experienced tech. it may be time to move on to another amp. in my shop it would be at least 65 bucks for the repair. so where did the "heat"/energy go from that point and what parts were affected. there may be a domino affect. burn one part, not usually.
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First thing I'd check is if the valves / tubes are plugged in properly (it doesn't take much to loosen them) Unplug the amp then take out all of the valves and put them back in again.

If that doesn't work, try swapping the preamp valves (the little ones) around (let them cool down first) that'll tell you if one of them is worn.

Failing that I'd try cleaning the gain and volume pots with some switch cleaner, and if that didn't work I'd bite the bullet and buy a new set of valves.

Hope that helps