2:90 volume jumps

[yakim]

Hello,
Recently my 2:90 makes volume jumps.
I'm playing with Boss GT-8 and after couple of minutes the volume reach really high for about 20-30 seconds and then returns to the normal volume - and that's happen again and again through the playing.
I searched for an answer and I read somewhere that dust in the tube sockets can cause the problem. So I clean every socket and I still have the problem.

Does someone know about this problem ?

Thanks,
Mickey

 

[ando]

It will mostly likely be bad tubes or bad volume pot. Try turning the volume knob from min to max back and forth very forcefully many times. Sometimes that will dislodge any dust build up on the contacts. If anything changes, you might have to change the pots. Although it fight fix the problem altogether.

If that doesn't work, try some new tubes.

 

[yakim]

Thanks , I'll try that.
I played again half hour ago and there was no volume jump.

How many hours life a 6L6 tube has?

 

[r_cod_81]

Try turning the volume knob from min to max back and forth very forcefully many times. Sometimes that will dislodge any dust build up on the contacts.

Get some switch/ contact cleaner, open up the amp and spray it into all of the pots. Leave for a few seconds then turn the post bothe ways through their full range of motion. This should help a lot! You don't need to do it forcefully (you could damage the pots), the cleaner dissolves grease and crap and then it flows out of the way.

 

[yakim]

Thanks , I'll try that also.

 

[ando]

Personally I don't like using contact cleaner. It often works to start with but can cause the dust inside the pot to become sticky and gummy - if that happens, it can make the problem worse. I use the dry method I mentioned above or I pop the casing off the pot and give it a manual cleanout. Just my personal opinion.

 

[elvis]

I had the exact same problem. Sent it to Mesa, they couldn't reproduce it. I think it was the volume pot. It was just one channel.

 

[yakim]

so how it got fix eventually ?

 

[elvis]

When it came back from Mesa it was fine. They said they resoldered some connections as a matter or maintenance, and they burned it in for several hours. Could have been as simple as bumping around during shipping dislodging some crud in the volume pot. We'll never know.