deville 410 loud hum

[andrulin1]

hello guys just joined this site. im hoping to find some help on my fender deville 410. about a week ago i started getting what i can only describe as a loud hum. the amp still works as far as being able to hear my guitar but when you crank the volume the hum/buzz gets louder too. i changed the tubes from another amp that works and still same thing. also checked the little ceramic resistors but they seem to be ok. the nearest fender certified amp repair shop is 4 hours away so im trying to see if anyone can help thanx guys.

[Chuck H]

Does this hum happen with nothing plugged into the amp? I mean, it should make some noise when it's cranked up, but more than usual?

Chuck

[Gtr_tech]

Likely a bad pwr tube. Try another set....I bet the hum is gone then.

[tim]

If the hum varies with the volume control, a likely suspect is a broken solder joint (or several) on one of the input jacks, or a hummy preamp tube (the tubes that Fender uses in their preamps seem to be "bottom of the barrel" tubes).

Back a few weeks ago I got a brand new Deville in the shop that was humming like crazy. It turned out that one of the filter caps was bad.

Also, I've seen the solder joints on the filter caps on these series amps break. Much humming, to say the least...

Careful in there. The voltages in these amps can kill you (or make you wish you were dead).

[52 Bill]

I agree with Tim here about the filter cap.

If you've already tried different tubes, have the filter caps in the pre-amp section checked. I've been seeing a lot of failures in those tiny 20uF caps.

How old is the amp? Are you the original owner? This would be covered by the warrantee.

[tim]

Are you the original owner? This would be covered by the warrantee.

As long as he has or can get a copy of his original receipt and it's under five years old. If it ends up being a tube, it's only 90 days.

[andrulin1]

guys thanx for all the replies ill try to answer all your questions. i am the original owner and the amp is about four years old. the hum/buzz does happen without my guitar being connected. it is uncommonly loud and unusual but does seem to increase with guitar connected. im not really into all the tech lingo so i have to ask what and where is filter cap and how can i check it & repair it. i hope i answered all your questions and thanx for the quick response.

p.s. i did try another set of tubes and same hum. thanx

[Chuck H]

Since the hum gets louder when you turn up the volume I'm thinking that is'a a hummy preamp tube or a bad ground in the preamp. Quite possibly on the input. Take a known good 12ax7 and swap it for each preamp tube. If that doesn't help it's not a tube. After that it gets more complicated. You'll need to remove the chassis, bleed the filter caps for the power supply and use a DMM to check for bad grounds.

If this seems overwhelming, good. There are potentialy LETHAL voltages inside a tube amp. Some amps can hold a lethal charge even after they are unplugged from the wall. Novices have no business inside electronics like this, but... We all got started sometime. You would need a multi meter and a schematic if you decide to go inside.

If the hum is there with nothing plugged in AND increases with the volume knob I'll bet it's a bad ground on the input jack. This is the most likely anyway because IIRC it's a PCB mounted jack and it gets alot of abuse. Just for giggles, Make sure your using an actual instrument cable and not a speaker cable between the guitar and amp. Since you said "without my guitar connected" I'm not sure if that means you still had a cable plugged in or not.

Chuck

[andrulin1]

no cable plugged in just the amp by itself. any suggestions at this point for this rookie? is there anyway to test the cable input? tried both inputs and still same thing are they wired parallel?

[tim]

andrulin1,
where are you located?

[andrulin1]

i live in the southern tip of texas.

[tim]

well, that sucks. If you were near where I live, I'd say drag it up and we'll throw it on the bench and I'd show you how to fix an amp..it's not that hard but you do have to know what to watch out for so you don't make a crispy critter out of yourself.

In order to get to the back of the circuit board to determine if you have broken solder joints on the back of the jacks, you have to partially remove the circuitboard from the amp. You said you've had the amp for 4 years. That's enough time to have the jacks break free of the solder pads and maybe even require new jacks (which are available from almost any amp parts place...I like www.tubesandmore.com P/N S-H506 and/or S-H507. I think Fender uses two S-H507s)

There's a good place to check out on the web here > http://studentweb.eku.edu/justin_holton/
It deals with the Hot Rod deluxe but there are more than just a few similarities between the Hot Rod and your amp, in fact, they're almost identical...read through the webpage and it gives you good pointers on making your amp safe to work on, how to replace the jacks, etc....

[oc disorder]

A good place to start is to check the input jacks as Tim says..
"If the hum varies with the volume control, a likely suspect is a broken solder joint (or several) on one of the input jacks"
If the jack nuts were loose so that the input jacks could move slightly
this could indicate the above.
Plugging into the power amp in jack should confirm if the hum is coming from the pre-amp. The signal will be very quiet but the hum should have dissapeared.
It's rather a big task first up to remove the circuit board ..taking off all the knobs and pot/jack nuts, cutting cable ties and perhaps removing some of the power transformer connections. Hint..take several photos of where the spade terminals connect from the transformer if you need to disconnect them or at least note the colour codes and the terminal designations.
Of course if caps need replacing it should be done then too 'cause you don't want to have to go through reassembly then find you have to pull it apart again.

Perhaps if the task is too daunting you could remove the whole chassis and bundle it up to send for repair.

Just a thought

[andrulin1]

thanx tim and ocd ill check out the web pages provided and make my decision on what i will do. either take a stab at it or send it off to get repaired. thanx for taking time to answer my questions.