Is an on/off switch for my amp's fan possible?

[mr_sooty]

I have a Classic 50, have had it for 9 years or so. Really love my amp. It has a fan cooling the tubes. Always whirred away in the background quietly, and never bothered me. But as the amps gotten older (and gone through a few repairs) the fan is getting noisier. It's not a problem at church or gigs, because the amp is up loud and you don't hear the fan at all (it's not THAT loud!), but it's starting to bug me at home when I'm practicing or jamming.

I don't think I should disconnect it completely, because it keeps the tubes cool. In 9 years I've never blown a tube. I recently replaced the power tubes because they were starting to crackle a little, but that's the first time I've ever replaced any.

So I was wondering if it would be possible to install an on/off switch for the fan, so that I could have it on unless it was bugging me, then I could just switch it off. From what I can see there are two black wires going to the fan. I don't know if the fan is an important part of the circuit or not, that is, I don't know if the power still needs to flow through with the switch off.

So what do you guys reckon? Do-able? Easy or not? Here's a link to a Scematic:

www.blueguitar.org/new/schem/peavey/c50schem.pdf

Doesn't help me at all cos I can't really understand it. Hopefully someone here can. I was thinking of just mounting a switch on the back panel of the amp.

Thanking you in advance.

[JohnH]

Hi sooty - I can't see any problem with adding the switch, except if the amp then overheats! My Marshall DSL401 also has 2x EL84 valves like yours, and did not come with a fan - so I added a couple of them because it did get really hot. Mine is rated at 40W while yours is 50W, which is alot to be getting out of these valves.

As to the switch, it would be good to know if the fan is running at mains voltage or at a lower dc voltage. Either way, a mains rated toggle switch mounted in a hole should do the job. I dont think that disconnecting the fan will affect anything else electrically, just thermally.

John

[sumgai]

sooty,

Why not just replace the fan, and be done with it?

It's just like your tubes - it's making noises like it's warning you that it's on its last legs. (Tube -> crackle...... fan -> noisy.)

Most likely you can do this yourself, but if your comfort level is suffering any anxieties, then let an amp guru look at it, and give you an opinion.


HTH





sumgai

[mr_sooty]

sumgai said:

sooty,

Why not just replace the fan, and be done with it?

It's just like your tubes - it's making noises like it's warning you that it's on its last legs. (Tube -> crackle...... fan -> noisy.)

Most likely you can do this yourself, but if your comfort level is suffering any anxieties, then let an amp guru look at it, and give you an opinion.

Oh, and John, mine has 4 x EL84's, not 2. Thing is, I'd only switch it off when I was running it quietly in my room or a studio. When it was getting driven harder the fan would be on.

So how do you hook up the switch? Are they just 2 points? How do you know which point is which? And how do I know which wire is positive and which is negative? (they're both black)
HTH





sumgai

Well I would consider that option, except that I wouldn't have the foggiest idea where to get a fan from.

[mr_sooty]

OK, I went with Sumgai's suggestion and replaced the fan. Managed to find one at a local shop that was an exact fit. Just about killed myself with a rather decent jolt at one point (it's amazing how those thing's store voltage when off), but got it all sorted, and it's much better now.

Thanks!

[sumgai]

sooty,

Glad you survived! ;D


Peavey has a reputation for using stock off-the-shelf parts and pieces, just so's you can more easily repair their gear. Fans tend to be standard sizes anyway, so you were doubly lucky. ;D



sumgai

[ashcatlt]

Yeah, umm.....

Don't do that again, whatever it was.

Sumbody or another around here had a link to the safe way to discharge those caps, no?

Coures, it's too late for sooty.

[mr_sooty]

The big lesson for the day - never work on an amp in bare feet! Can anyone say 'permanently grounded?'