#1
Alright so a few weeks ago I got a new Jet City JCA2112RC. I love the thing. But, just a few minutes ago, I was playing, and all the sudden I look in the little grate at the tubes and one of them is BRIGHT orange, like it was completely lit up, as opposed to what it normally looks like. The other tube was lit up just as it normally is and looked completely normal. But the one right next to it like I said, the entire thing was completely lit up as if it was on fire. So I put it in standby, and turned the amp off for a while.

Went to play again, had it in standby for a minute and a half, started everything up, was playing, then all of the sudden my guitar volume got lower without me ever changing any volume. I look into the grate again, and the one tube was a very bright orange again and I heard a loud pop and crackle and then it honestly looked like the thing started on fire. There were blue and white sparks and what looked like flames inside of it, coming from the one tube. This is the second or third time I've heard this pop/crackle sound, but this is the first time I've actually been looking at the tubes whilst it happens.

Obviously, this is a problem I am seriously pissed right now, but I have little knowledge with all the technical stuff about tube amps. I'm guess I blew something in the amp? Any help would be greatly appreciated.
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Last edited by shredibanez24 at Sep 30, 2011,
#2
the tube you saw blow up?


that's what you blew up.
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#3
Quote by gregs1020
the tube you saw blow up?


that's what you blew up.

Yeah... I figured, but how and why?
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Fulltone OCD Overdrive
Boss SD-1 Overdrive
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Jet City JCA2112RC 20W
#4
it's gonna take a tube autopsy to figure that out.

post pics of the borked one. is it an EL84?

it could just be a crappy stock tube that took too much abuse in shipping or it just sucked from birth.

if it is an EL84 that blew, pop in a fresh pair of JJs.

(that means replace both EL84s with JJs.)

edit: turn the amp off and unplug it from the power outlet first please.
I wondered why the frisbee was getting bigger, then it hit me.
Last edited by gregs1020 at Sep 30, 2011,
#5
yeah they're EL84's. How do I go about replacing them? Is it a fairly easy procedure?
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10/10 Slater is amazing

Fender Deluxe Roadhouse Strat
Ibanez RG4EXFM1
Washburn D46S
Dunlop Original Crybaby Wah
Fulltone OCD Overdrive
Boss SD-1 Overdrive
MXR M-148 Micro Chorus
Jet City JCA2112RC 20W
#6
yes.

with the amp unplugged from it's power source, you pull the tube directly away from it's base.

you should, i said should, replace them both with a matched pair of jj el84 tubes.

keep the one that didn't go berzerk as a spare.

pull straight out when removing, and push straight in when installing. make sure you line the pins up correctly when installing, they only go in one way and the pins need to line up directly with the pin slots. if it seems like they don't want to come out when removing, slightly, i said slightly wiggle them side to side just enough to get them loose. you don't jack them back and forth, that's a really bad idea. just slightly wiggle, and only if needed.

once the replacement is finished, you can plug it back into it's power source.
I wondered why the frisbee was getting bigger, then it hit me.
Last edited by gregs1020 at Sep 30, 2011,
#7
alright man, will do. Thanks for the help. I'll probably call around town and see if any stores have JJ EL84's in stock so I can avoid ordering them online as well.

thanks again man
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Ha ha love you to dude ;-)

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10/10 Slater is amazing

Fender Deluxe Roadhouse Strat
Ibanez RG4EXFM1
Washburn D46S
Dunlop Original Crybaby Wah
Fulltone OCD Overdrive
Boss SD-1 Overdrive
MXR M-148 Micro Chorus
Jet City JCA2112RC 20W
#8
anytime, glad to help.

i know for a fact that my sam ash has jjs in stock. you are in NY and they have a couple stores out there so phone one if possible.

if they are too far to drive to they can send you a pair if they have them in stock, providing they ship them from the store you would likely have them overnight being in the same state.

good luck.
I wondered why the frisbee was getting bigger, then it hit me.
#9
since you decided to play it again AFTER you noticed it was super bright and it popped and crackled and looked like would catch on fire there is a good (fair) chance you also blew a screen grid resistor. You would have to inspect the circuit board for scarring but that can also be dangerous (opening an amp chassis) and would probably negate the warranty anyway.

It's called 'red-plating' it is not a good thing for a tube amp. Hopefully a new tube will fix her up. Good luck.
Last edited by 311ZOSOVHJH at Sep 30, 2011,
#10
Quote by 311ZOSOVHJH
since you decided to play it again AFTER you noticed it was super bright and it popped and crackled and looked like would catch on fire there is a good (fair) chance you also blew a screen grid resistor. You would have to inspect the circuit board for scarring but that can also be dangerous (opening an amp chassis) and would probably negate the warranty anyway.

It's called 'red-plating' it is not a good thing for a tube amp. Hopefully a new tube will fix her up. Good luck.

The thing is though is that it's made this same sound about two times before this but I was convinced it was just a bad cable or something, until just now when I happened to look at it when it was red plating and realized it actually was a serious problem. I might take it to a tech and have him check it out to see if I ended up f*cking anything else up besides the one tube.
Quote by Robchappers
Ha ha love you to dude ;-)

Quote by fearofthemark
10/10 Slater is amazing

Fender Deluxe Roadhouse Strat
Ibanez RG4EXFM1
Washburn D46S
Dunlop Original Crybaby Wah
Fulltone OCD Overdrive
Boss SD-1 Overdrive
MXR M-148 Micro Chorus
Jet City JCA2112RC 20W
#11
that is probably a wise decision ....just to be sure. If a red-plating tube took a resistor out with it then putting a new tube in will only cause that tube to probably blow and may even cause further damage.

http://www.google.com/search?sclient=psy-ab&hl=en&site=&source=hp&q=blown+screen+grid+resistor&btnK=Google+Search
Last edited by 311ZOSOVHJH at Sep 30, 2011,
#12
yeah I'm gonna make some calls tomorrow and see if I can get someone to look at it. thanks for the help man
Quote by Robchappers
Ha ha love you to dude ;-)

Quote by fearofthemark
10/10 Slater is amazing

Fender Deluxe Roadhouse Strat
Ibanez RG4EXFM1
Washburn D46S
Dunlop Original Crybaby Wah
Fulltone OCD Overdrive
Boss SD-1 Overdrive
MXR M-148 Micro Chorus
Jet City JCA2112RC 20W
#13
you have at least a 1 year mfg warranty from Jet City.

you could always have it checked out for free since the amp is having an issue.

shouldn't cost you a dime.
I wondered why the frisbee was getting bigger, then it hit me.