Solve one question...

[CharvelRocker]

...and then have some more Okay, heres a weird one. I just noticed that my amp is making an odd burning smell, and it kind of scares me. This is actually the second time, first was when a speaker cable touched the power tubes for a split second. No smoke anywhere and the tubes look fine. It sounds fine too. My first thought is I had the tube guard (picture of one on a Crate VC Series setup identical to mine) that I had out and maybe just now since its on the tubes again, the smell is of the foam on it. The only other thing I can think is my filter cap(s?) are going bad. Any tube amp people have an idea of whats going on?

[yard dawg]

Maybe it just farted hahah

[Dreamland_Rebel]

you might have burned through a screen resister and or a tube. i would have it checked out.

when that happened to my mesa mark III i had been using it on 3 tubes from the time i smelled that smell till i took it in.

[CharvelRocker]

you might have burned through a screen resister and or a tube. i would have it checked out.

when that happened to my mesa mark III i had been using it on 3 tubes from the time i smelled that smell till i took it in.

Out of interest, can this have any negative effects on the amp? Also how long did you run yours before taking it in? I want to fire it up one more time to make sure its not something simple, like some dust got on the tubes or something and that my tubes are glowing like they should, but I don't want to if it could damage my amp.

EDIT: If it helps, it only happens once I've had it on for about 5 minutes.

EDIT 2: Well, I pulled out the chassis today, and everything looked good. In fact, it looked like it had just come out of the factory. No damaged looking parts, no odd looking filter caps, no burns on the PCB....maybe it is just a bit of residue from the speaker cable on a power tube or dust on them.

EDIT 3:
EDIT: Ok, now this is bothering me again. I noticed its not a lingering smell. Something on the tubes should start to smell as it heats up, and linger awhile due to the heat of a tube shouldn't it? Like I said, its not a dust burning smell, or cigarette smell (which is what blown filter caps and sometimes output transformers smell like from what I know/been told), just a wire burning one, like when you're soldering and tag the wire. I think its going to have to a tech, as this one has me puzzled.

[Rsmacker]

Is this the same amp that you pulled the Power Valves out and weren't sure if it was important to plug them in the correct sockets?

[CharvelRocker]

Is this the same amp that you pulled the Power Valves out and weren't sure if it was important to plug them in the correct sockets?

Yeah, but I was thinking as to plugging them in the right way. Either way, I guess it was just some crap on the tubes, as I tried it one more time and it stopped, amp sounds good, everything looks and works fine.

[JacksonDean]

Yeah, but I was thinking as to plugging them in the right way. Either way, I guess it was just some crap on the tubes, as I tried it one more time and it stopped, amp sounds good, everything looks and works fine.

... then BOOM!

[Dreamland_Rebel]

dude you've fried a tube and a screen resistor.

i smelled the same thing on mine. that is the smell of the screen resistor burning internally. i ran mine for 6 months after it happend, unaware of the damage i had really done. and it was still able to be fixed back to perfect. you won't notice a drastic change in sound because you are now running on 3 tubes instead of 4.

my tech called me the day after i took it in and said, "you did know you had only been running on 3 tubes right?" and then said "i'm surprized you didn't smell the screen resistor burn up when it happened." i told him that i had a while back but everything looked ok. then he asked me if i had plugged a tube in the wrong way...

so yeah, this is a direct result of plugging in your tube the wrong way. you need to take it in and have it taken care of.

[CharvelRocker]

dude you've fried a tube and a screen resistor.

i smelled the same thing on mine. that is the smell of the screen resistor burning internally. i ran mine for 6 months after it happend, unaware of the damage i had really done. and it was still able to be fixed back to perfect. you won't notice a drastic change in sound because you are now running on 3 tubes instead of 4.

my tech called me the day after i took it in and said, "you did know you had only been running on 3 tubes right?" and then said "i'm surprized you didn't smell the screen resistor burn up when it happened." i told him that i had a while back but everything looked ok. then he asked me if i had plugged a tube in the wrong way...

so yeah, this is a direct result of plugging in your tube the wrong way. you need to take it in and have it taken care of.

What doesn't make sense though is if I was running on only 1 (I have 2 in mine btw) I would notice a sound drop would I not? Volume is still consistent. Likewise, they both plug in the same way, so by that logic both screen resistors should of burnt up

[Rsmacker]

So how the fuck did you manage to plug the valve in the wrong way (sorry, a tube is something you use to insert a gerbil with), surely the socket is a key-wayed affair, you must have forced the thing in (bit like a gerbil I guess). Be gentle, if it doesn't go in, don't push - you'll bend the pins at the very least.

If your amp has 2 power valves, and one is fucked you would notice it, at least you will when your output transformer goes. That is going to be fucking expensive.

Get it checked.

[CharvelRocker]

So how the fuck did you manage to plug the valve in the wrong way (sorry, a tube is something you use to insert a gerbil with), surely the socket is a key-wayed affair, you must have forced the thing in (bit like a gerbil I guess). Be gentle, if it doesn't go in, don't push - you'll bend the pins at the very least.

If your amp has 2 power valves, and one is fucked you would notice it, at least you will when your output transformer goes. That is going to be fucking expensive.

Get it checked.

I'm not saying I put them in wrong. I thought there was the chance of it, but I ruled it out for several reasons: They went in the same way (oh bite me), it sounds the same, and they glow the same. The reason I came back to the debris-on-the-tube theory is because because it ended with no adverse effect on the tone, tube, or anythign else.

[Soap]

Maybe it just farted hahah

In the voice of Beavis, "hah, hmn, hah, mghmn you said farted."

[Rsmacker]

Have you replaced the output valves yourself, or did the previous owner (if it had one)? If so, was the amp properly biassed? If there's no burning but it smells like "hot wire", do the valves look OK - is there any red glow on them, on the plating, rather than on the tips? Does it feel like the amp is getting seriously warm?

I take it you are still playing it and it hasn't gone pop on you yet?

[CharvelRocker]

Have you replaced the output valves yourself, or did the previous owner (if it had one)? If so, was the amp properly biassed? If there's no burning but it smells like "hot wire", do the valves look OK - is there any red glow on them, on the plating, rather than on the tips? Does it feel like the amp is getting seriously warm?

I take it you are still playing it and it hasn't gone pop on you yet?

Its previous owner was an amp tech. It is biased well, with everything a nice warm glow. Besides occasional tube noise, its quiet. There was no burning I could see anywhere on the amp, even on the PCB. The amp isn't getting any warmer than it ever has. I'm still playing and its fine. Also, I di dmentiont his smell stopped about 2 weeks ago right?

[Rsmacker]

Its previous owner was an amp tech. It is biased well, with everything a nice warm glow. Besides occasional tube noise, its quiet. There was no burning I could see anywhere on the amp, even on the PCB. The amp isn't getting any warmer than it ever has. I'm still playing and its fine. Also, I di dmentiont his smell stopped about 2 weeks ago right?

So what's the problem then??? :ROTF:
Only trying to help you get to the bottom of your original problem!

Incidentally, how do you know it is biassed well, have you metered across the grid, or is there a probe point (oo-er) like on a Fender Twin? The previous owner being an amp tech is no real comfort, they are more likely to re-biass slightly "hotter" to get that sound, at the price of lower valve life etc, whereas mere mortals like you or I would tend to leave things the fuck alone unless we understand them. Kinda like a car tuning expert tinkering with ignition settings - I know a little about cars, but it runs fine thank-you-very-much, I'll not mess with it!
Maybe get him to give it a once-over, for your peace of mind, and tell him a load of armchair experts have been telling you allsorts of shite on the Interweb, and you need to tell them all they are wrong!!!

Finally, if you haven't metered the voltages, because you are not technically that way inclined, DON'T!!! I'm sure you are well aware of this already, but valve amps carry (and hold, long after they are switched off), SERIOUS voltages which will spoil your day. Permanently. Not to be fucked with lightly!!