Fender Hot Rod Deville 410

[Prsgtr]

Hi my name is Sean, I'm new to the forum. I've got an issue with my Deville 410 amp. It probably needs new tubes but before I waste money I was hoping maybesomeone could diagnose my issue. The amp sounds great on the clean channel (even when using effects) when I switch over to the distortion in the amp it sounds like the speakers are blown and makes an ugly "wah wah wah wah" sound. The sound gets increasingly worse if I turn any of the tone pots (bass, middle,treble) and if I switch to "more drive" it gets even worse. I've never changed the tubes in the amp and I'm sure its time to change them. I figure if I'm gonna spend any money on getting it fixed (the amp is pretty much mint) I might wanna modify the amp just to make it a little different than if you bought it from fender. I LOVE this amp it sounds great and I got a good deal on it brand new when I worked for a local music store. Any suggestions as far as what I should do or what can be modified to make this a killer amp would be much appreciated.

[Prsgtr]

Nobody has any suggestions for me?

[Jazz P Bass]

If you want to troubleshoot the amp, you will need test equipment, (a volt meter, minimum)& soldering & desoldering equipment.
My take on it would be C36 is bad.
It is a 22uf/ 500 volt capacitor.
With your meter set to read volts ac you can measure the ripple that the cap is supposed to eliminate. (measure directly across the cap)
If the cap is bad, you will see that ripple as a voltage reading.
I don't know why, but the dirty channel will show up as a problem when the cap is bad, but the clean channel will not.
Other than reading the Vac ripple, a well proven method is to temporarily attach another cap, with the same capacity & voltage rating.
If the measured ripple is reduced, the original cap is most probably bad.
I have attached the layout diagram, C36 is all the way off to the left.

[Prsgtr]

Thanks. Ill be looking into it for sure. There's nobody in my area servicing amps, so I guess to save money I'm gonna have to use my limited knowledge and the forums help to get this thing back to normal.

[Jazz P Bass]

Here is the Fender cap.
Link: Capacitor AE AX 22uF 500V 0024819000

[Prsgtr]

Awesome thanks again hope it works, I soldered all kinds of things before should I be worried about trying to do this by myself. I don't have any high end soldering guns or anything. I figured I could test with the multimeter then if I'm afraid to solder it myself... Who would you contact? For instance if I were to search the yellow pages what type of company might help me out with the soldering?

[Jazz P Bass]

An amp repair shop?
Seriously the 'job' is going to be getting the board out of the chassis.
If you do remove it, mark down where every wire you remove goes.(there are about 15)
First you have to identify the problem, no?

[Prsgtr]

Yeah I'm noticing that now looking inside the amp now, amazed how perfectly clean it still is inside there not a speck of dust. Well I'd hoped it was something I could fix. We don't have any amp repair shops in town so guess I'm screwed unless I wanna pay alot of money for shipping back and forth. Still I guess it's cheaper than a new amp.

[52 Bill]

Well, you say that you haven't changed tubes since you got it. If your problem is only in the drive channel, then you only really need to try changing one preamp tube to see if it is tube related. Try swapping the 12AX7 tubes around any difference? I'd mark the tubes so that you know where you started and can return them to the original spots if there is or isn't an improvement.

If Jazz is right about C36, you can test the theory by just jumpering a new cap across the original one without any soldering. Then if the new cap solves the problem you can pull the board and deal with the soldering. The cost of one cap shouldn't be too much of an investment for you.

[Prsgtr]

Thanks ill give that a shot, and get the capacitor ordered. If replacing the tubes doesn't work

[Prsgtr]

I was told by an online amp repair company that "once stuff starts to go... It's only a matter of time before more stuff goes wrong with this amp" I'm kinda worried about that, I'm not worried about it if its just the tubes. How much truth is there to that statement? The amp is like brand new, it was never hauled around or even used that much.

[Jazz P Bass]

While it is true that these Fender series of amps had 'issues', that does not mean a whole lot.
How many thousands of these did they sell?
How many 'break'?
Knowing what can & does go wrong can help in deciding whether or not anything needs to be done to the amp.
After an inspection of the amp.
In my mind, wholesale condemnation before a visual inspection is rubbish.
Fix it.
Play it.

[Prsgtr]

That's what I was thinking. Thanks for all your input and speedy replies

[olddawg]

Before you start removing wires or components, take several pictures of your chassis and lead dress. It will save you a lot of headaches later.

[dmartn149]

Sean. I am only slightly more experienced than you seem to be, so I can't really help you fix this amp. I just wanted to add two bits of advice. #1. Tube amps have voltage in them that is much higher than what comes out of the wall socket, so be very careful. #2. If you decide to send it to a tech you can take the chassis out of the cab, and just send the amp chassis (no speakers or cab) it's not so much to ship that way.