Peavey XR684F Problem...Need help or thoughts here...Please!

[soundgodwannabe]

I just got a XR684F from a friend that stopped using it because he said he could hear crackling in the speakers when he used it a couple of years ago. I bought it from him...took it home connected it and ran it. It sounded fine for the 30 minutes I tested it out. The other night in practice...it shows up after about 45 minutes...crackling from the speakers. I unplugged it from the wall. Put it in a 6 way surge bar and it went away. I turned it on again the other night...it's back. I changed out the fuse from the 8A250V it had and put in a 5A250V (all I had) and it sounded fine up until about 45 minutes of being turned on...nothing going through it...just plugged in. The crackling noise is back.
Anyone got any thoughts before sending it off to be worked on?
Its not a scratchy pot or anything like that...its more like electrical static/crackling.

[Enzo]

OK, the surge bar stopped it? WHen it came back was the thing still on the bar? If a surge arrestor cures the problem, then the amp is not likely at fault.

If it is in the amp, then isolate the problem.

Does turning ALL controls to zero make it stop? Does ANY control have ANY effect on the sound of the noise?

[soundgodwannabe]

Can't isolate it at the moment...

I have looked at the unit after turning it on. I plugged it directly into the wall (like it did the first time) and I turned it on for over an hour and no static or crackling. So, it didn't do it this time. The other times, it would be working just fine then all of a sudden...static and crackling...not like a dirty pot noise. I turned on the laptop in the room with wireless after about 15 minutes, thinking it might be the source as my clock radio doesn't like the wireless connection. However, it still didn't do it after about 45 minutes.
We have practice tomorrow night with 2 vocals going through it. I will see what it does if it does it at all. Not everytime it does it...maybe when it heats ups or something?

[Enzo]

And your surge thing? Does it ever do it while connected to that?

[soundgodwannabe]

Surge protector does not change it...

I connected it to the surge protector tonight before practice. It didn't make any noises all night until we were done and were packing things up. It just started making the electrical noises. I turned every knob back and forth. Unplugged all the connections (except for the speaker cables). Turned down every channel (gain, monitor, and effects)and (0) out all the eq's.

[Enzo]

OK, so the noise is not from the power lines.

When it does it next, ball up your fist and whack the top hard. Does that stop the noise, or change the noise in some way? Or make it worse? We are looking for a loose connection or weak solder joint now.