Burnt my EVH 5153 today

[Coma]

Well, seems like I'm playing a zero-sum game. Three weeks ago I was gonna splurge on rebuildning my pedal board. Fancy loop switcher and all that. Then I stripped the base plate of one of my Floyds. Got the spare parts today, yaaaay! Plan was band practice, then home, pour myself a whiskey, repair guitar. Get to band practice, hit the first few chords... sound cuts out and amp starts giving off a foul, burning smell. Cut the power, pull out all the plugs, check the fuse - it's intact.

Connect the main power again, plug in guitar. All lights working, channel switching working, still no sound. Crank the volume on the red channel, and I get a nasty, thin and tinny distorted sound. Turn off and unplug. No maore amp for Uncle Coma.

What do you guys think? Power tube gone bad? Or something worse?

 

[dxlxntxxlxr]

Re: Burnt my EVH 5153 today

Output transformer maybe?

 

[Gtrjunior]

Re: Burnt my EVH 5153 today

I’d definitely check tubes first....even possible PI tube. Usually when a power tube blows it takes the fuse...not always though...

 

[Coma]

Re: Burnt my EVH 5153 today

I’d definitely check tubes first....even possible PI tube. Usually when a power tube blows it takes the fuse...not always though...

What is a PI tube?

 

[Rex_Rocker]

Re: Burnt my EVH 5153 today

What is a PI tube?

Phase inverter. It's the last 12AX7 in the chain before the power tubes.

 

[Gtrjunior]

Re: Burnt my EVH 5153 today

What is a PI tube?

Yup, Rex nailed it.

 

[devastone]

Re: Burnt my EVH 5153 today

Unfortunately foul burning smell usually means something other than tubes. Could be anything from a transformer ($$$) to diodes or a resistor($) burning out.

 

[Coma]

Re: Burnt my EVH 5153 today

Brought it home and checked the tubes today. Everything seems intact. Really, really hoping it's not the output transformer.

 

[Waterbound]

Re: Burnt my EVH 5153 today

I’m guessing (unfortunately) that it’s the transformer just based on past personal experiences but hopefully I’m wrong. You

 

[devastone]

Re: Burnt my EVH 5153 today

Again, tubes don't make a burning smell when they die, not saying it is the transformer, but I'm 99% sure it's not a tube, although one could have been taken out/failed due to/because of the as yet undiagnosed problem. Hopefully it was just a rectifier diode or something.

 

[Coma]

Re: Burnt my EVH 5153 today

Brought it home and checked the tubes today. Everything seems intact. Really, really hoping it's not the output transformer.

 

[Gtrjunior]

Re: Burnt my EVH 5153 today

Again, tubes don't make a burning smell when they die, not saying it is the transformer, but I'm 99% sure it's not a tube, although one could have been taken out/failed due to/because of the as yet undiagnosed problem. Hopefully it was just a rectifier diode or something.

Last time blew out a power tube I smelled a faint burning smell....you know, that electronic burnt smell.
But it was faint. I suppose depending on just how strong the burning smell is, it could still be a blown power tube.

@Coma. Also, last time I blew out a tube there was no visible signs of damage. So just because you don’t se obvious signs of a blown tube doesn’t mean that they are not the culprit.


All that said, I’m not a tech. My tube amp repair is limited to changing and biasing tubes. I just figured new tubes would be the cheapest route to go first. Especially if you have a spare set already and can bias yourself.
@devastone probably knows way more about the inner workings of a tube amp than I do, so he likely has a deeper insight.

 

[devastone]

Re: Burnt my EVH 5153 today

Tubes are sealed glass bottles, therefore no smell can escape. If you smelled something, something got hot, maybe not hot enough to totally kill it, but something got hot.

 

[Kamanda~SD]

Re: Burnt my EVH 5153 today

I'd certainly be worried it was the tranny. blown tubes usually don't 'look' blown, and they usually don't smell themselves, BUT a blown tube can cause other components to burn up. Bring it to a tech.

Also, if it was/ is the tranny, double check the impedance of your cab (with a multimeter...don't just read the sticker). I've seen (especially on switchable cabs) where one input isn't quite right and the impedance is off, so you think you're plugging into 16ohms where it's really 4...and poof.

 

[Gtrjunior]

Re: Burnt my EVH 5153 today

Tubes are sealed glass bottles, therefore no smell can escape. If you smelled something, something got hot, maybe not hot enough to totally kill it, but something got hot.

Just curious...if the glass cracked and the inner gas leaked out, under heat would there be a smell from that?

 

[dystrust]

Re: Burnt my EVH 5153 today

Just curious...if the glass cracked and the inner gas leaked out, under heat would there be a smell from that?

There isn't any inner gas (or as close to zero gas as it's possible to make), hence vacuum tubes.

 

[Coma]

Re: Burnt my EVH 5153 today

Good news: No blown tubes or transformers. Blown resistor though. The thing was built into a ceramic casing witha metal plate on the bottom, I guess to prevent other components from getting damaged in case it blew up. And blew up it did indeed. The ceramic casing is split wide open, and the metal plate is cracked in two. Smells terrible too. While it was opened, discoveres that one of the preamp tubes' socket connecting pins was never soldered onto the board to begin with. Very strange. Gonna email EVH and see what they have to say about it.

As for the cause: Most likely improperly set load. Lower cab was not plugged in correctly. Not sure if the cable had just shook loose or if the guys we share rehersal space with had bumped it or something. Sucks, but at least its a cheap thing to repair. Ordering new speaker cables as well, just to be safe.

 

[dystrust]

Re: Burnt my EVH 5153 today

As for the cause: Most likely improperly set load. Lower cab was not plugged in correctly. Not sure if the cable had just shook loose or if the guys we share rehersal space with had bumped it or something. Sucks, but at least its a cheap thing to repair. Ordering new speaker cables as well, just to be safe.

It's always a good idea to re-check all of your connections before playing if you have a shared rehearsal space. My band had one of those about 15 years ago and the guys in the other band claimed that they never touched my amp. That doesn't change the fact that I'd often find knobs had been turned or that it was plugged into a totally different cabinet. One of them even broke the input jack on my 2555 and wouldn't own up to it.

In my defense this was in 2002 when Jubilees weren't worth a ton on the used market. I'd never leave that amp in a rehearsal space now.

 

[GoldenVulture]

Re: Burnt my EVH 5153 today

Good news: No blown tubes or transformers. Blown resistor though. The thing was built into a ceramic casing witha metal plate on the bottom, I guess to prevent other components from getting damaged in case it blew up. And blew up it did indeed. The ceramic casing is split wide open, and the metal plate is cracked in two. Smells terrible too. While it was opened, discoveres that one of the preamp tubes' socket connecting pins was never soldered onto the board to begin with. Very strange. Gonna email EVH and see what they have to say about it.

As for the cause: Most likely improperly set load. Lower cab was not plugged in correctly. Not sure if the cable had just shook loose or if the guys we share rehersal space with had bumped it or something. Sucks, but at least its a cheap thing to repair. Ordering new speaker cables as well, just to be safe.

- http://www.synthmanuals.com/manuals/evh/evh_5150iii_50w_amp_head/schematics_vietnam/ -

The ceramic encased resistor is a high wattage resistor. Has the board got a number where the resistor is ? EG R132.

PS: if you crack a valve it will usually discolour to white on the inside of the glass .

 

[Coma]

Re: Burnt my EVH 5153 today

It's R19. 390 ohm 10 w. And I unfortunately can't get it from the electronics store I usually source stuff from, but will order one through my budy's work. Might take a while til it gets here, though.