Peavey XR 400B PA Head has an intermitent Problem

[Platefire]

This is the PA I use at home for me and the wife songs used several times each week.

This is the Symptoms:

1-Has cut off completely sometimes. When it cuts off completely, the pilot light is still on, just no sound.  When I turn it on latter, it will come back on operating normal.  That makes me think it's a heat sensor switch maybe cutting things off.

2-Sometimes as your playing the sounds will go down in volume like someone turning the volume down and then come back up within a few seconds.

3-I have gone through periods of time it works perfectly, then all of a sudden it will start doing symptoms 1 and 2 again. 

I have avoided opening it up because it's solid state and Peavey stacks their boards in all different directions to complicate the situation. So I have been thinking of maybe it's time for a new one.
The thing is this little four channel 100 watt head with reverb is perfect for my needs at home, it just needs to work right all the time. So I suppose I wouldn't be worth my salt if I didn't at least try to repair it. So I will look for a schematic and if any of you SS experienced guys has any suggestions--I would appreciate it.
Platefire

[PRR]

You can buy another for under $200 shipped; there's one on Reverb.com

Behringer probably has a similar but better unit under $200 new retail.

In this case, I would call Peavey Support. Hartley probably won't answer the phone (he used to). And they'd be correct to tell you that if you don't buy new stuff once in a while, they go broke and lose their jobs. But I've heard good things about Peavey support going out of their way on old gear.

Does it get hot? A headbanger band could probably toast it, I'm not imagining you and your wife would. So heat would be a sign of some internal problem.

Have you cleaned (at least plugged in/out many times) all the Insert jacks? Especially the ones you never use. Tarnish builds up, sound won't go through. (This does not quite fit the symptom that it comes back on its own, but worth a try.)

[shooter]

But I've heard good things about Peavey support

+1
I called on a couple amps I fixed before I found here, they were great, prices were very reasonable, I asked if they would sell me an un-populated main board, they said sure, but for $50 more we'll sell you a populated one, I chose option 2.

[Platefire]

Thanks PRR and Shooter!

Yeah I realize I can pickup up another head pretty cheap, but you know I'm a cheap-skate so I always milk something for all I can get it, to a fault.

Hate to admit it but I've actually banged on it in frustration and it came back on before. This last time I did that it didn't work. It did come on after I let it sit turned off and turned it back on and worked fine. I haven't noticed it getting hot. Last time it cut out, I felt the back around where the power cord going in the chassis, and it was warm, not hot.

I sent Peavey Customer Service a e-mail requesting a schematic. In the past, they have always complied.

I also got a patch cord, my Deoxit, would spray a little on the plug tip and plugged in and out several times on each unused  input jack. The only ones I use is the XLR's. I fired it up to test after that and it was loud and powerful. So we will continue to use it and see how it does. Platefire

[PRR]

> I sent Peavey Customer Service a e-mail

Seriously. If the Deoxit isn't the cure, *call* their support line. They may know a common fault, save you a heap of time.

[Platefire]

OK, Thanks!

[Platefire]

Peavey sent schematics on pdf files. One was way to big and I couldn't find a way to convert it down to a smaller size on my PC, so I scanned copies. I will also try to attach the pdf of the power amp. Platefire

[Platefire]

I've used it several times for short periods since I cleaned the 1/4" jacks, no prob! Need to do a long session and see how it does. Platefire

[Platefire]

Another follow up on this one. Since I've cleaned all the un-used 1/4" jacks with Deoxit hasn't cut out a single time. Good call PRR. I'm gonna call this a fix! Platefire

[shooter]

I'm gonna call this a fix!

I used to warranty all my work, 5minutes, or 5miles, whichever comes 1st

[Platefire]

Well the head was given to me 9 years ago, was about 20 years old when given to me, been in constant
use  since I got it-----so I'd dare say it's on borrowed time. But I'll continue to ride this bronco as long
As it keeps bucking:>}

[Platefire]

Here two months later, PA Head still working great---no problem. Cleaning those 1/4" jacks sure did the trick. Platefire