When i use the over drive it will switch back and forth between the clean channel. But when im on the clean channel it is fine.

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.

For the Drive channel you need to use the Drive control AND the MASTER volume control. When the Drive channel is active, the Channel Indicator lamp should be RED indicating the Drive Channel is active. The Drive control knob is used to adjust the preamp volume and distortion level of the Drive Channel. This gives you a clue as to what to check if adjusting the controls doesn't work -- the preamp tubes. Having said that, ONLY try to check these tubes with the amp OFF! Never stick your hand up into the chassis of a live amp. It could be lethal. Your preamp tubes are the ones farthest from where the power cord enters the chassis. They have a rubber like stabilizer on them. They have a tendency to wiggle loose, which is part of the reason for the stabilizer. Again, if you're not familiar with the insides...stay out and get an amp tech to help you.

The Normal Channel only uses the Volume Control to adjust volume.

When i turn on my 212R it turns on in drive channel. if footswith is plugged in, then it turns on in the clean channel, but after switching in drive it is impossible to switch it back in clean channel. What could be wrong? Swith position doesnt change anything and it seems like switch is OK.

Have you tried another guitar?
Switch the cable?
There might be some RF interference

Wayne, There's a time to take the amp to a pro shop andf get it done right. It' saves time and headaches, and also keeps you from inadvertantly smoking other parts or yourself. Now is that time.

This is likely a bad jack for the foot pedal, or a problem with the pedal and cable. The jacks are junk and even with the pedal unplugged the switch contacts on this jack will vibrate and cause your problem.

If the footswitch is not switching correctly, open it up and check for any shorts or a defective switch. Sounds like it's a problem with the switch.

Probably there are dirty contacts inside the assign switch, also it could be a bad solder contact on the switch or there around.

The switch can either be removed and cleaned or replaced.

Cleaning is a bit delicate procedure, but can actually be done, you need to take the switch apart, taking care not to damage any of the parts, then you need to clean the inner contacts and the contact making clamps with some fine sandpaper.

Be sure to put everything back together as it was otherwise the switch may not work properly or it may not work at all (be gentle with the contact making clamps, they can easily be damaged / squashed).

It could also be a problem with faders or preamps, but i would take a look at the switch first.

regards

3rq8 (Triarcuate)

Insain is distorted but cleen is not

Replace the switch. You gave no make/model number for your amp but if it has a jack for foot pedal operation of clean/dist function then try that. (on most amps) it will switch in spite of a bad front panel switch.