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Ever changed a tube in an amp while it is on?
Old 11th April 2010
  #31
js1
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I wouldn't do it, but the biggest risk with preamp tubes is burning your hand. Current's pretty low, doubt that you'd get much in the way of arcing happening, and you'd have to work pretty hard to touch the high voltage or short two pins together. Tube stages typically are in series, so you're basically interrupting the circuit.

Power stage - a slightly different story.

js
Old 11th April 2010
  #32
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glenn Taylor's Avatar
 

No but I have.....
1. Played guitar on a wet rug with bare feet. (peed my pants)
2. Discharged a 250v cap with my bare hands. (felt a little quirt in the dirt).
3. Threw a towel over a honey bee then lifted it up. (it stung me).
4. Told my wife I bought a Manley vari mu. ( had to by her a car )
5. Stuck a butter knife in a toaster ([email protected]$##dm that hurt like a motha)
6. Put up goofy post's on GS........
Old 11th April 2010
  #33
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This is pretty close to asking if we have ever touched a ground wire.

No. But I came pretty dang close one in a live sound situation XD.

Bad, bad idea sir.
Old 11th April 2010
  #34
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Do what you want, but realize that the plate voltage on the power amp tubes is as high a 400 VDC.

That is A LOT of wallop because it is DC.
For perspective... I accidently touched the 250 VDC supply in my MCI 538C's plasma meter power supply once.
I'll describe it as gentleman-like as I can and still get the experience across...
It knocked the F*CK out of me.

The pre-amp tubes run at a lower voltage, but it still isn't good for anything in the circuit to be stressed that way.
THere is just no point in doing it.
Old 11th April 2010
  #35
ktf
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Quote:
Originally Posted by glenn Taylor View Post
No but I have.....
1. Played guitar on a wet rug with bare feet. (peed my pants)
2. Discharged a 250v cap with my bare hands. (felt a little quirt in the dirt).
3. Threw a towel over a honey bee then lifted it up. (it stung me).
4. Told my wife I bought a Manley vari mu. ( had to by her a car )
5. Stuck a butter knife in a toaster ([email protected]$##dm that hurt like a motha)
6. Put up goofy post's on GS........
Luv you man!

Changed allot of hot tubes - still typing. Glass is not a good conductor. Still it better to turn it off.
Old 11th April 2010
  #36
I hate when that happens.....

Quote:
Originally Posted by dbbubba View Post

I'll describe it as gentleman-like as I can and still get the experience across...
It knocked the F*CK out of me.
I hate when that happens..........




Willie and Frankie

Frankie ... Christopher Guest
Willie ... Billy Crystal


[Hallway in an office building at night. Uniformed security guards Willie and Frankie -- two working class nebbishes with thick New York accents -- carry flashlights and walk down the hall testing the knobs on the locked office doors.]

Frankie: Hey, Willie.

Willie: Hi, Frankie.

Frankie: How's the west wing?

Willie: All secure.

Frankie: That's good.

Willie: You know somethin', Frank?

Frankie: What?

Willie: I - I - I don't like bein' a night watchman. There - there's nobody here.

Frankie: It means we're doin' our job, Willie. And doin' it well.

Willie: Yeah, but I - I - I - I - I liked it better when we - when we was messengers, I mean, and then I - I was out - I was meetin' people.

Frankie: Like that woman over at Scheidelman's Suits, right?

Willie: [reluctantly] I dropped her. Yeah, she was all over me. All over me, she was. I - I - I need room to breathe.

Frankie: I know, Willie. The stallion needs to run. [Willie nods solemnly in agreement] And run free.

Willie: [rubs his shoulder in pain] Shoo, boy.

Frankie: What's the matter?

Willie: Eh, my shoulder hurts. You know - you know that narrow hallway in the boiler room? The one with the, uh--?

Frankie: Exposed bolts comin' out o' the wall?

Willie: Yeah. Well, every time I walk past it, the bolts dig right into my shoulder. I-- It's very painful.

Frankie: Boy. You wanna talk about some pain? I bought one o' them linoleum knives the other day, you know?

Willie: With the double edge?

Frankie: Right.

Willie: Yeah?

Frankie: So, I go home, you know, and I spread my toes apart and I just start sawing, back and forth and back and forth, you know?

Willie: Mm hmm.

Frankie: And I take a little thing o' Tobasco sauce, you know?

Willie: Yeah.

Frankie: And just dump it on there. Talk about a hotfoot, mister! Boy, that was rough.

Willie: Yeah, I know what you mean. You know, the other day, I took one o' them, uh--?

Frankie: Meat thermometers?

Willie: Yeah! And I just shoved it into my ear, you know? As far as it could go, you know? But then I took one o' them, uh--?

Frankie: Ball-peen hammers?

Willie: Right. And just whacked it a few times right in there, you know.

Frankie: Boy, that must smart.

Willie: I know! I HATE when THAT happens.

Frankie: You know what I hate?

Willie: What?

Frankie: I go into the kitchen, I open the drawer, you know?

Willie: Uh huh?

Frankie: And I take out a, uh--

Willie: Carrot scraper?

Frankie: Right. And I stick it up my nose, you know, and I'm rootin' it around, and, you know, gettin' all the mucus membranes out o' there, you know? And then I take one o' them, uh--?

Willie: Mentholated eucalyptus cough drops?

Frankie: Right. And I stick it-- wedge it up there, you know? I take a couple o' whiffs, boy. Heh, ya feel like your head's gonna explode.

Willie: Boy, isn't THAT the truth? It's like the other night. I'm in the attic and I got a bunch o' mousetraps, ya know?

Frankie: Right.

Willie: And, for bait, I used a big piece of, uh--

Frankie: Camembert?

Willie: Right. So, so I set the trap, right? A-a-a-a-and I wanna see if the trap was gonna work, right? So I got the Camembert in there.

Frankie: Right.

Willie: But every time I went to taste the cheese, the thing came down right on my tongue! ... I'm tellin' ya -- after forty, fifty times, I - I - I couldn't even feel the cheese, much less taste it. I hate when THAT happens, I'll tell ya that.

Frankie: Boy, you know what I hate? I hate-- I got a gross o' them, uh--?

Willie: Razor blades?

Frankie: No.

Willie: Fish hooks?

Frankie: No.

Willie: Ah?

Frankie: Thumb tacks.

Willie: Ah! Yeah.

Frankie: Right?

Willie: Yeah.

Frankie: So I bring 'em home, you know, and I sprinkle 'em all out over the floor, you know?

Willie: Points up?

Frankie: Right.

Willie: Uh huh.

Frankie: Then I strip down to the nude and I just ROLL back and forth across the room, ya know? Stickin' in all over my body. Then I jump in a hot tub and just soak.

Willie: Mm hmm.

Frankie: Hate that.

Willie: Sounds very painful.

Frankie: Very painful.

Willie: [heavy sigh] Boy. So what're ya gonna do now?

Frankie: Eh, I'm gonna check fifteen.

Willie: Yeah. I'm gonna check nine.

Frankie: Okay.

[They head back up the hall, testing doorknobs as they go. Finally, they pause to give each other a friendly pat on the shoulder.]

Frankie: Good night, Willie!

[Grinning, they exchange dismissive waves and exit in opposite directions around the corners at the far end of the hallway. Fade out.]
Old 11th April 2010
  #37
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rkopald's Avatar
Quote:
Originally Posted by dbbubba View Post
Do what you want, but realize that the plate voltage on the power amp tubes is as high a 400 VDC.
My amp runs at ~460 or so (my idle current is 36 mA), and I've read that some amps get near 600!! YIKES. I get this high 500 figure from a Ted Weber reference book on tube amps, which I'm sure a lot of you have.
Hiwatts I think run the highest plate voltages?? That's KRAZY.
Old 11th April 2010
  #38
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Quote:
Originally Posted by norman View Post
did it cross your mind to turn it off?
Up until the 3rd tube.. yes. After that, I completely spaced it - but I turned it back off for the 5th one.
Old 11th April 2010
  #39
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jp22's Avatar
 

Quote:
Originally Posted by adeptusmajor View Post
wow...

and you're still alive?!

congratulations!!
A question I often ask myself.
Old 11th April 2010
  #40
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jp22's Avatar
 

Quote:
Originally Posted by Bater View Post
WHY?
mistake
Old 11th April 2010
  #41
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jp22's Avatar
 

Quote:
Originally Posted by js1 View Post
I wouldn't do it, but the biggest risk with preamp tubes is burning your hand. Current's pretty low, doubt that you'd get much in the way of arcing happening, and you'd have to work pretty hard to touch the high voltage or short two pins together. Tube stages typically are in series, so you're basically interrupting the circuit.

Power stage - a slightly different story.

js
This sounds pretty logical. Incidentally, I used my bare fingers, as usual.
Old 11th April 2010
  #42
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Quote:
Originally Posted by carllock View Post
No, but once I tried to light a shot of Barcardi 151 on fire...
Never tried that before. I take it didn't go over so well for you? Doesn't sound like too big a deal..
Old 11th April 2010
  #43
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Quote:
Originally Posted by FFTT View Post
Not a good idea for the amp's circuitry or your own personal safety.
This crossed my mind, but somewhat after the fact. I think I do agree though.
Old 11th April 2010
  #44
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Quote:
Originally Posted by djemberecords View Post
I read that some of the guitar amp techs use an oven mitt and change the preamp tubes hot looking for the perfect combination. NEVER hot swap the power tubes.

I have done some service over the years and never did it. It just does not seem like a good idea to me.
An oven mitt.. sounds a bit clumsy for such a small area where preamp tubes usually reside. I'm not too sure how possible that would be. As for swapping power tubes, yeah - I assume that does need extra care, in which case I would probably unplug the amp from the wall before doing anything.
Old 11th April 2010
  #45
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jp22's Avatar
 

Quote:
Originally Posted by Dimes View Post
That just seems like a bad idea all the way around. Why would you not turn the amp off? Do you also change your oil with the engine running?
I did actually.. 3x, the 4th I spaced it but the 5th I did again. Yes, oil into a car with the engine running would be a mess !
Old 11th April 2010
  #46
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jp22's Avatar
 

Quote:
Originally Posted by indravayu View Post
Preamp tube - yes....power amp tube - no (that could damage your amp).
I would assume..
Old 11th April 2010
  #47
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jp22's Avatar
 

Quote:
Originally Posted by MasterTrax View Post
Nope, never tried that, but once when I was 12 I tried to pull out a tight plug from a plugged-in extension cord with my teeth.

Haven't done that again since.
I think most of us have probably done something like this. In my case, I was a bit younger and it involved an electrical outlet. The only thing I remember is my fingers were all completely purple and a bit charred looking. Fortunately, I didn't sustain any permanent damage (in my fingers that is).
Old 11th April 2010
  #48
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jp22's Avatar
 

Quote:
Originally Posted by sniperschool View Post
ashamed to admit that i do it all the time when testing tubes out
Wow.. so judging by most comments in this topic, many might agree that would be somewhat like playing roulette?
Old 11th April 2010
  #49
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rkopald's Avatar
Being from Detroit, this may not come as a shock, but I knew a guy in junior high that liked to "get high" by touching the exposed wires of a plugged in, stolen exit sign to his tongue.
Detroit. Geeyah.


edit: ha. Shock.. I guess it is an actual shock..

Last edited by rkopald; 11th April 2010 at 08:16 AM.. Reason: "shock"
Old 11th April 2010
  #50
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Quote:
Originally Posted by kafka View Post
I once touched the spark plug on my lawnmower while it was still running. And I lick 9V batteries to see if they're still fresh. Does that count?
I've done both of these as well and I do in fact test batteries the same way. This might be pretty common though, not sure..
Old 11th April 2010
  #51
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I guess this thread goes to show that the vast majority of folks on this forum think something can kill you based on a complete lack of understanding about how one might actually be killed by a preamp tube.

Putting a tube in a socket gives you several seconds while it warms up to run to the other side of the room and hide.

Take what people say on here with a grain of salt. Lots of misinformation.
Old 11th April 2010
  #52
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Quote:
Originally Posted by cavern View Post
it doesn't matter, you won't get a shock from a tube anymore than you would from touching just one electrical wire.
i've been doing it for years, so does the tech at my local music store. he puts it on the counter and checks for bad tubes that way.
use a paper towel or gloves,you could burn your fingers. don't do it if you feel uncomfortable with it.
working inside the amp is a different story though."carefull there".
and never touch two electrical wires.heh
Funny.. the tubes in my amp don't seem to get that hot. Maybe it's how the amp is setup or something, not sure. I used my bare fingers and it didn't bother me. I think I'll probably use some type of thin glove next time though. The "oven mitt" suggestion someone said was interesting. lol Although, I don't know how possible that would be in such a small area.
Old 11th April 2010
  #53
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Quote:
Originally Posted by corworld View Post
I guess this thread goes to show that the vast majority of folks on this forum think something can kill you based on a complete lack of understanding about how one might actually be killed by a preamp tube.

Putting a tube in a socket gives you several seconds while it warms up to run to the other side of the room and hide.

Take what people say on here with a grain of salt. Lots of misinformation.
Sounds logical. Hide ! (with an oven mitt)
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