Amp is overheating!! Help please!

[0903hunter]

Hey there, I just bought a fender Jazz the other day and the guy I bought it from threw a Peavey Basic 60 in with it (now called a peavey basic 112). The problem is that I can only play on it for about 15 min. before it overheats and shuts itself off. Sometimes it cuts out even quicker when playing at louder volumes. So I took the amplifier out of the actual cabinet and set it upside down on top so that it could have air to keep it cooler. It doesn't cut out as easily when I do this but at high volumes I start to lose power still and the sound breaks up and distorts when hitting notes hard, like slap stuff? There are a few components that get really hot to the touch on the circuit board. Wondering where to start and what to do?? Please help, any advice is welcome. Thanks!

[jackcheez]

Now you know why he threw it in.

For heaven's sake just be careful with that touching stuff.

[Chasarms]

You're pushing it too hard.

The good news is if you keep playing it like that, it will eventually stop cutting out after 15 minutes.

The bad news is that it wont work at all.

[0903hunter]

Yeah, i know. But it cuts out at low volumes after about 10 to 15 minutes of light playing when I am not pushing it at all? There has to be some component on the board that must need to be replaced....but what?

[chokeslam512]

Is there a fan? Are the vents blocked?

[BassmanPaul]

If the amp needs work I suggest you take it to a tech. Finding out just what "bits" need to be replaced is how he earns his pay.

Paul

[craig.p]

One thing that comes to mind is a speaker voice coil that's partially shorted from abuse/overheating, and therefore offering too low an impedance to the power amp section. As a test, can you connect the head to an external cab, preferably 8 ohms or higher?

[RickenBoogie]

It cost you nothing, so, if you want it to work, take it to an amp tech and pay him to get it up and running.

[0903hunter]

There is no fan or vents on the amp or in the cabinet. I was thinking that might solve the problem. I can try hooking it up to another cab and seeing if that works and if it still overheats. I don't really have the extra money to spend right now on taking it to a tech.

[Jerrold Tiers]

Originally Posted by 0903hunter

I don't really have the extra money to spend right now on taking it to a tech.

Then you have a problem.... meanwhile it will only get more expensive to fix if you keep using it.

One piece of data you can get for when you CAN take it to a tech..... if you just leave it ON for 15 min, does it still get hot? or do you have to actually play through it?

if it still gets hot, the bias may be badly set (too high), and you can suggest that to the tech....... or at least tell the tech that you don't need to even play through it for it to shut off. If he has any brains, he will know to look at bias then.

[Chasarms]

Originally Posted by 0903hunter

Yeah, i know. But it cuts out at low volumes after about 10 to 15 minutes of light playing when I am not pushing it at all? There has to be some component on the board that must need to be replaced....but what?

I would be very surprised to learn that it is the speaker.

It is more likely as you suggest. Unfortunately, unless there is very obvious visual evidence as to the culprit, there is no way to identify it without a schematic of the design that includes the correct values and someone with the knowledge and patience to start on one end and test all of parts with a DMM until the issue is found. It could be one or more of any of those transistors on the board.

[0903hunter]

Thank you all for the help! I will probably just take it to a tech as you suggest since it doesn't look like an easy fix for me to do by myself.