Amp getting hotter than it should

tom once dead · #1 11-02-2009, 01:56 AM

At a gig on saturday after our half hour set I went to take the speaker lead etc out of the back of my svt 3 pro; and I noticed the amp was a LOT hotter than it should get. Its in a gator 4L rack, in the bottom two spaces with a tuner in the top space, and a non-rackmount wireless that sits in between the two. The gig was very hot (Being in the tropical north).

seeing as the head is designed to be put in a rack, I cant see why doing so would cause it to heat up so much.

pdubya · #2 11-02-2009, 02:09 AM

hmmm....know the feeling.every time i toured north of brisvegas i got the same thing.......ampegs are notorious for that mate.i would suggest maybe getting a fan installed if you haven´t already got one.
also turn it off when not using it.sounds like it´s due for a service?my old svt was notorious for getting hot,and would blow capacitors before the transformer because of the heat.hope that helps

www.myspace.com/dubthemagicdragon

spideyjg · #3 11-02-2009, 08:13 AM

I see a fan or exhaust port in the back. Where does the air come in and go out?

Some brainiac amp makers have the thing suck cool air in from the back or front, and rather than the heat blast out the opposite end of the rack, they have it blow out the side of the amp into the rack. Makes it your own little 4RU easy bake oven.

That is lousy thermal management in my book. Get a fan.

Jim

BassmanPaul · #4 11-02-2009, 01:40 PM

If the amp is a few years old it could be that the cooling tunnel has a build up of crud partially blocking it. It may just meed to be thoroughly vacuumed out.

Paul

phatbass · #5 11-02-2009, 01:57 PM

Aussie conditions - make sure there's plenty of airflow around the amp and ensure any vents have plenty of clearance. Personally I'd leave at least one rack space totally clear on top of the amp.

And +1 to opening it up and cleaning out the dust and crud that builds up....

tom once dead · #6 11-02-2009, 03:07 PM

It is an SLM, so maybe dust is the culprit. How would I go about it though, just take off the top and get a vacum in there?

RickenBoogie · #7 11-02-2009, 03:11 PM

...or a feather duster, or compressed air (in a can).

BassmanPaul · #8 11-02-2009, 04:29 PM

No not compressed air!

The muck that's inside an amp could consist of almost anything including bacteria, asbestos and mould. It should be considered hazardous and disposed of accordingly. I use a vacuum with a crevice tool and a soft paint brush. If you use air all that stuff becomes airborne. Not such a good idea. Wear a mask.

Paul

kranahan · #9 11-02-2009, 07:46 PM

do not vacuum.. you could break off and possibly suck up some of the parts. use compressed air and a mask. I just used compressed air on my svt-cl and blew a fortune of dust and grime out of there. Be sure to spray every spot including the fan.

Fine Cut · #10 11-03-2009, 02:46 AM

i've seen a few guys set their racks up with a space open over their amps, and rig up a couple 40mm or 80mm computer case fans at the rear to blow air into the rack over the top of the amp. if the amp has any venting on the top, it'll help scavenge the heat off and away from the amp. it can still help to keep interior temps down a bit even if there's no direct ventilation on top by keeping the air inside the rack around the amp cooler. i plan to do something similar to this once i ever get ahold of a decent rack...

ps. use LED fans for a cool lighted effect

tom once dead · #11 11-03-2009, 05:46 PM

I opened it up, and it really wasnt that dusty at all, hardly even any on the fan.

jellymax · #12 11-03-2009, 06:48 PM

the output mosfet transformers can get very hot if not adjusted properly (mosfet bias).
obviously your fan has to be operational...

there is a blue adjustment control inside. a small movement makes a big difference
so be very careful. cold means lower output, hot means higher output. you need
to be somewhere in between. i did it myself, but cannot recommend that to anyone

hope that helps

Jerrold Tiers · #13 11-03-2009, 08:34 PM

Does the fan speed up as the unit gets hot?

if not, the temperature control circuit isn't working right, and the amp might be without overtemp protection.

The temperature sensor for overtemp also operates a fan speed circuit. As it gets hotter, the fan is supposed to speed up, keeping it cool. if the fan isn't doing that, the overtemp may not be capable of shutting down if it get really hot.

tom once dead · #14 11-04-2009, 12:56 AM

Is it possible that the fan is getting as fast at it can get? The gig would have been in at least 30 degrees Celcius.

BillMason · #15 11-04-2009, 08:39 AM

Hate to ask, but keep in mind that I don't know you or your experience at all - but what impedance are your cabs?

Jerrold Tiers · #16 11-04-2009, 08:04 PM

Quote:

Originally Posted by tom once dead

Is it possible that the fan is getting as fast at it can get? The gig would have been in at least 30 degrees Celcius.

of course.... but the point is whether the fan was slower and quieter when you turn it on, and whether it speeded up.

if NOT, problem with temp sensor/fan speed

If fan DOES speed up, then maybe another issue. 30C isn't very hot, was it also sitting out in the sun (outside gig)? The sun can make a 30C day into a 50C day for the amp.

Could have been hot day/sun

Could be bias set high

Could be you beat heck out of it.

Can't tell from here. Does the fan change speeds?

tom once dead · #17 11-04-2009, 11:12 PM

running a 4 ohm 410. It was inside a hall with no ventilation, about 50 people inside, and lights heating up the stage. I do run high input gain, but not near full, if I play normally the light doesn't come on.

I was thinking it could be the rack, but that doesnt make sence as the head was made to go into a rack.

spideyjg · #18 11-04-2009, 11:19 PM

Quote:

Originally Posted by tom once dead

I was thinking it could be the rack, but that doesnt make sence as the head was made to go into a rack.

How does cool air get in and hot air out? Just cause it is meant to mount in a rack doesn't mean it is ideal.

A buddy had a SWR rig that vented side to side inside the rack and overheated often.

Jim

Nightlyraider · #19 11-05-2009, 08:06 AM

I'd vote that the amp was just too enclosed in the rack.

I have my SVT4 rackmounted (this can make alot more heat I know, but just sharing) in a 5 unit rack all by itself in the middle. Both ends of the rack are open and there is at least an inch or two around the chassis that air can flow through.

I haven't looked inside a 3 before, but I know other ampegs use a fan on the far right of the amplifier blowing over heatsinks with air exiting on the far left of the amplifier. There is almost zero front to back air motion. If your amp is anything like this, having little to no space around it is a bad thing.

If you "need" all your equipment in a single unit, they do make cases with side vents and would highly recommend that.

boombap · #20 11-05-2009, 08:16 AM

1- Ditch the tuner or set it on top of the rack.

2- Move your wireless up a space so that you now have a space between the two.

3- Get a fan.