There is a Fender Deville at the house where my band practices, and I use it instead of having to lug around my amp.
Today, since it was 60 degrees out and sunny, we practiced outdoors. I used the Deville, and had the volume at about 5 .
After playing for about a half an hour, it started making wierd noises. They were sort of like out of tune distortion/grinding noises. The problem got worse over several minutes, and then the amp stopped working alltogether. I turned it off, and removed the fuse, which was blown.
The amp is still under warranty (thank god), but since I don't own the amp, I am very worried as to why the fuse blew. The amp was plugged into a very heavy extension cord, which was plugged into an outlet on the side of the house. I won't be able to replace the fuse until tomorrow, but want to know if anyone has ever experienced something similar with one of these amps, and if anyone has any ideas as to why the amp failed.
I would take it back since its still under warranty. To start with a fuse never blows without something else being wrong. There are a few reasons that can cause to happen. Like if the AC shorts to a grounded chassis, a power surge and the AC line current exceed the fuse's rating, AC power wiring or B+ power wiring is faulty/shorted, a power tube shorted out, a failing power supply filter cap, it lost bias or biased incorrectly, the power section maybe oscillating at a to high a frequency to hear, faulty power transformer.
These should at least give you some information as a starting point. Which also will give you some knowledge if a tech does have to work on the amp. Maybe even ask if you can watch as its being worked on to learn more about tube amps. Think Safety
Joe
How long was the extention cord you were using? No matter how thick of a gauge it was they have a distance rating. The longer the chord the less true power you are getting the unit and can casue serious problems.
My first thought since you were out side it, that you were underpowering it, but over working it. IN any gig I have played with many amps indoors or out I have never had volume past 3 and even that probably was too loud.
I hope the fuse fixes it, and it has cooled down enough to have no issue, but if it was an electrical supply issue, you will be lucky if the manufacturer covers it under warranty.
Best of luck,
Josh
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Joe's suggestions are right on target. Out of the causes he listed, I'd guess a failing power tube as the most likely cause. They're supposed to be "vacuum tubes," but the vacuum's never perfect. If one's got slightly too much gas in it, ionized gas molecules will hit the negative control grid and remove electrons from it, making it more positive. That lets more current flow, which ionizes more gas, and the tube gets hotter in the process, which "cooks" out even more trapped gas molecules from the inner structures of the tube, and it just gets worse and worse. if there were no fuse to blow, something else would. This is called "thermal runaway," and is a common death mode of power tubes. An amp with a runaway tube in it behaves pretty much as you described.
Catastrophic tube failures are far more common in new tubes than in tubes that have been in service for a while, BTW. That's why I'm not a proponent of swapping tubes for the heck of it in hopes of finding a special tone, or to replace them for "preventive maintenance." If they're working, leave 'em alone.
"A cheerful heart is good medicine."
Playing at 5 is not that hard on this amp, I have played entire gigs with my HRD at 6 and never had a problem. Now, if it was getting improper power, that is another story. But these are tough amps and can handle a lot.
But 5 is pretty darn loud. :D
I am not an amp tech by any means, but I think Ricochet is probably correct. 90% of tube amp problems are the tubes. Perhaps a power tube started cooking and the fuse blew as he suggested. Take a look at the tubes first.
How old is this amp? If this amp has been played hard for a year or two, it is very likely that one of the tubes just wore out.
Good luck and let us know what you find out. Hopefully it was just a tube. That is not too expensive at all.
If you know something better than Rock and Roll, I'd like to hear it - Jerry Lee Lewis
Ok, that power tube theory seems plausible. This amp is relatively new, and i don't think that it's real owner has ever had it cranked before. I think it was bought about a year and a half ago, and has enjoyed only light use. Therefore, this was the first time that these power tubes had a real workout. It there any way to check if they're ok?
Also, the power cord was about 100' long. That theory was actually my first thought, and is still possible.
Obviously, the power supply failing is possible. Let's keep our fingers crossed that that isn't what's wrong.
Oh, and Wes, playing it on 5 was awesome!
xg5a
Your best bet is simply to take it in for servicing under the warranty. It may have been the long powercord, or perhaps it had nothing whatsoever to do with that. I would put the blown fuse back in and take it in just as it was when it quit on you.
If you know something better than Rock and Roll, I'd like to hear it - Jerry Lee Lewis
xg5a
Your best bet is simply to take it in for servicing under the warranty. It may have been the long powercord, or perhaps it had nothing whatsoever to do with that. I would put the blown fuse back in and take it in just as it was when it quit on you.
Well, I think the amp's owner is going to put a new fuse in it, and see if it works normally. If it doesn't, he'll take it in for servicing under the warranty.
That sure sounds good to me!
Update:
Well, we got the new fuse in it, and the amp seems fine.
For now, i'll leave well enough alone.
What a scare!
If it was a gassy power tube, it'll happen again when you play it hard and get it good and hot.
"A cheerful heart is good medicine."
If it was a gassy power tube, it'll happen again when you play it hard and get it good and hot.
Hmmm, i'll let the owner know. He may want to go ahead and replace the power tubes just in case.
Is there a way to test the power tubes to see which one is faulty(if there is a faulty one)? If so, would both tubes have to be replaced?
Heat can be a factor. If the amp was in direct sunlight and with limited ventilation (maybe a jacket dropped over the back?), it might overheat and then misbehave.
If it was purchased at a dependable place, they should be willing to give it a thorough check-up, not just change the fuse and say "See, fixed it."
Laz
Is there a way to test the power tubes to see which one is faulty(if there is a faulty one)? If so, would both tubes have to be replaced?Many of the old tube testers have a "GAS" test. The way it works is that the tube's warmed up, a plate voltage is applied, and a resistance is switched in and out between the grid and ground. If there's more than some specified maximum change in the plate current, it's because of gas ions changing the grid bias. The test isn't conclusive. The tube's not being operated under full power conditions, and the gas becomes more of a problem the hotter the tube gets.
Usually these tubes are replaced in pairs, and lots of folks get them matched. As we've previously discussed on the board, some of us (like ForrokStar) think that's very important, and I don't. With new tubes, if I could identify the one causing the problem, I'd just replace it with one like it, but that's my approach. (And from messages I've gotten from others, it seems to be the approach of factory Fender and Marshall techs when an amp's returned for a problem.) I don't want to start a squabble, but there are differences of opinion on whether to always replace in matched pairs. Not knowing which one was the problem, I'd replace both anyway.
"A cheerful heart is good medicine."
