Tube got so hot it charred the label!

Hey guys!

Check this out:

I ran this tube in my bassplayers Musicman amp, which blew up.
I thought the tubes might still be fine, so I decided to try them in my RT2/50.
Turns out one of them ran so hot it actually charred the red JJ label to black!
(that's not the light, the label is actually this dark!)

Just wanted to share it..
I had turned the bias all the way down to 0.
It actually read zero on the right tube, the left tube read 88 - 90 :shock:
That's when I decided to turn it off and pull them out, before they'd ruin my RT2/50!
Can a tube blowing like this actually harm your amp? (besides blowing the fuse related to it)?

I had a Mesa tube glow blood red on me, not sure for how long and it flacked the mesa label off, and killed my amp.

Tech said, the tube shorted and fried two tube plates and some resistors, so if he was telling the truth then yeah it can hurt your amp, if your getting the same thing happening.

it was covered by mesa warranty for me, so not much worries but it can get expensive.

slashnstrings said:

I had a Mesa tube glow blood red on me, not sure for how long and it flacked the mesa label off, and killed my amp.

Tech said, the tube shorted and fried two tube plates and some resistors, so if he was telling the truth then yeah it can hurt your amp, if your getting the same thing happening.

it was covered by mesa warranty for me, so not much worries but it can get expensive.

Click to expand...

Hmm okay then.

Well my amp seems fine, but one of the channels does have some noise.
I switched the tubes in the channels around to check, and it's definitly only channel 1 that gives noise..

Come to think of it, I only switched the powertubes, maybe one of the PI's is the culprit!

Yeah "RED PLATING" is a very dangerous affair. If you see a tube glow red then you have about 30 seconds until the damage begins. If you see black spots on the glass then you lost the tube and maybe the amp. And yes a PI can cause red plating. As far as damaging your amp, Randall swears that the fuse blowing should prevent damage to the amp. You may also want to check the bias resistors on the amp that did blew the tube. If one of those are blown it can overcook a tube too.

Peace, Joshua

Mister Joshua said:

Yeah "RED PLATING" is a very dangerous affair. If you see a tube glow red then you have about 30 seconds until the damage begins. If you see black spots on the glass then you lost the tube and maybe the amp. And yes a PI can cause red plating. As far as damaging your amp, Randall swears that the fuse blowing should prevent damage to the amp. You may also want to check the bias resistors on the amp that did blew the tube. If one of those are blown it can overcook a tube too.

Peace, Joshua

Click to expand...

I only had the tube in there for about 10 seconds, I spotted the bias reading and hit the power switch right away.
So I guess I was lucky then.

Yeah the Musicman needs to be checked out by a tech, for sure.

OK...I confused about that tube...Is it a JJ or Ruby? Or are they the same??

Mister Joshua said:

Yeah "RED PLATING" is a very dangerous affair. If you see a tube glow red then you have about 30 seconds until the damage begins. If you see black spots on the glass then you lost the tube and maybe the amp. And yes a PI can cause red plating. As far as damaging your amp, Randall swears that the fuse blowing should prevent damage to the amp. You may also want to check the bias resistors on the amp that did blew the tube. If one of those are blown it can overcook a tube too.

Peace, Joshua

Click to expand...

I only had the tube in there for about 10 seconds, I spotted the bias reading and hit the power switch right away.
So I guess I was lucky then.

Yeah the Musicman needs to be checked out by a tech, for sure.

By the way, I swapped the PI tubes, and the power tubes .. and it makes no difference in the noise from channel 1 (well, there's light variation, but still channel 2 is virtually silent and channel 1 is noisy).
It's grey noise type of noise, it get's louder when I turn up the volume..

It's easily drowned out by any guitar sound, but still.. it has me uneasy.

Mattfig said:

OK...I confused about that tube...Is it a JJ or Ruby? Or are they the same??

Click to expand...

Ruby AFAIK does the same as TAD, they select tubes from other manufacturers and sell them as their own brand.
They do do claim to do some selection based on the quality of the tubes..

So those TAD 6L6GC-STR's that you love? Shuguang 6L6GC-STR
(I have both, the tube base of both of these has "TAD" stamped on them.. no discernible tonal difference, absolutely identical looks)

EDIT:
Looky here: http://www.magicparts.com/new/matched_power_tubes.htm
And you'll see they sell JJ's (6L6GCCZ/JJ ), Electro Harmonix (6L6GCEH ), Sovtek (5881R and 5881WXT+ ) etc. etc. you get the point

I blew up my Marshall about a year ago. it was BAD. one of the EL34s burnt a HOLE in the side. My friend borrowed the amp and had it fixed, but that blew me away, and like an idiot I threw away the tube. I took a look when I pulled it out and saw the cared label, when to poke it and it flaked off reviling the hole... I have never liked Grove Tubes to be honest.

MadHatter_Lurch said:

I blew up my Marshall about a year ago. it was BAD. one of the EL34s burnt a HOLE in the side. My friend borrowed the amp and had it fixed, but that blew me away, and like an idiot I threw away the tube. I took a look when I pulled it out and saw the cared label, when to poke it and it flaked off reviling the hole... I have never liked Grove Tubes to be honest.

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Holy crap! :shock: Looks like I really was lucky!
Even with the fuses, I don't really like the idea of testing their protection..

I had a quad set of Ruby tubes that came in my 2001 Koch Multitone... I was playing one day when i heard a barely audible hum that got slowly louder. Decided to take a look round back and one tube was glowing red hot. Turned the amp off right away and used another amp for the day. Came back to it and tried... everything was normal. Played that amp with those tubes for a year after then sold it. Guy who bought it is a friend and still plays the amp with those tubes. Go figure !?!?

MadHatter_Lurch said:

I blew up my Marshall about a year ago. it was BAD. one of the EL34s burnt a HOLE in the side. My friend borrowed the amp and had it fixed, but that blew me away, and like an idiot I threw away the tube. I took a look when I pulled it out and saw the cared label, when to poke it and it flaked off reviling the hole... I have never liked Grove Tubes to be honest.

Click to expand...

Let's not forget the story where he tried it again after the retube, and blew a fuse Then he thought "Oh, it's just blown a fuse for NO APPARENT REASON. I'll just get some aluminum foil and wrap it around the fuse to connect the leads and play through it some more..."

I believe he said it was some pillar of rainbow colored flames?

And of course, MY fumble with power tubes: Biasing up my amp after putting 4 tubes in it (two of my 5881's, two JJ 6L6's) and while biasing the first tube, I had taken the pot all the way up thinking "Hmm.. The value should be going up further than this.. Wait a secod.. the pot is all the way up. What's that burning smell? Why is my.. HOLY HELL MY POWER TUBE IS STARTING TO LOOK LIKE CAPTAIN AMERICA!" (Actually, I was thinking Darth Vader's lightsaber at the time, but Captain America seems more fitting since it was filled with blue and had the beam of red in the center)
I looked at my volt meter and had it set to read 20v, not 2v *facepalm* So, I was running a Sovtek 5881/6L6GC at 183mv for a few seconds. Swiftly took the bias back down after that and proceeded to bias the other tubes.

khingpynn said:

I had a quad set of Ruby tubes that came in my 2001 Koch Multitone... I was playing one day when i heard a barely audible hum that got slowly louder. Decided to take a look round back and one tube was glowing red hot. Turned the amp off right away and used another amp for the day. Came back to it and tried... everything was normal. Played that amp with those tubes for a year after then sold it. Guy who bought it is a friend and still plays the amp with those tubes. Go figure !?!?

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Weird stuff man, I guess tubes have their strange moments too..
How would you compare the Koch to the RM by the way?
I always found them very compressed.. not very organic sounding.
A "too perfect" sound for me, perfect for others of course

great amp... well built... channel one for american cleans, two for light breakup and crunch, three for full on metal. Over all in the recto family of tone. Ultimatly I choose MTS over the traditional three channel amp... not becuase I dislike the Koch or anything... MTS is far more flexible and the tones are as good or better.

the first two channels are voiced warm but the eq and the speaker dampening allows you to alter that. Channel three can sound very clinical with the speaker dampening and eq or it can get tight and dark with a fast attack.

My favorite channels are ch#3 first then Ch#2.

The closest Module to the Koch ch#3 sound is the 1086... thats partly why I like this module so much.
The mid switch on the 1086 closly resembles the speaker dampening of the Koch.

cheers

khingpynn said:

great amp... well built... channel one for american cleans, two for light breakup and crunch, three for full on metal. Over all in the recto family of tone. Ultimatly I choose MTS over the traditional three channel amp... not becuase I dislike the Koch or anything... MTS is far more flexible and the tones are as good or better.

the first two channels are voiced warm but the eq and the speaker dampening allows you to alter that. Channel three can sound very clinical with the speaker dampening and eq or it can get tight and dark with a fast attack.

My favorite channels are ch#3 first then Ch#2.

The closest Module to the Koch ch#3 sound is the 1086... thats partly why I like this module so much.
The mid switch on the 1086 closly resembles the speaker dampening of the Koch.

cheers

Click to expand...

Well that's a good description, because I dislike the 1086 as well haha.
Everyone to his own
I like the Recto-ish character, but not all the time, I far prefer the Soldano voicing on my Salvado to the recto voicing on it.. the mids are much more to my liking there.
I found the scooped setting on the 1086 completely useless to me.

That said: this is all in standard or drop-D tuning, when I tune down lower the 1086 does come alive more to me.

So the EL34s have a problem with red plating and fucking up your amp. I got a quad of JJ EL34s in my RM100 right now and I have'nt had a problem yet. Does anyone know if KT66s have any issues in the Randall?

Talk about resurrecting a thread

So tonight I did some rearranging and plugged my RM1250 back in after it sitting for a month or so after opening it up and checking out it's midi board to compare to a bad one.

And my tubes glowed like no other blue and red in the middle like mojo's. The biasing wouldn't do anything. So after a few seconds I shut it down. Let it sit for a bit and reset bias knob for each and tried again and turned each all the way down and still nothing.

Thoughts on what's going on? It worked fine before I opened and put the top back on, possibly pushed the biasing pots on accident maybe causing the issue? Need to call Randall in the AM and see they suggest and if they have a few of these pots handy.

I peeked inside again before posting this and man those biasing pots have no support so they have to go in just right or risk getting pushed against the spacer ring.

That's strange. I had a similar issue tonight. I swapped out the 6l6s for some el34s. Bias was setting strange then jumped up to some ridiculous number and I had a captain America tube going too. Pulled the chassis and noticed the bias pot bent.

Put her back together, but still only one test point works and I need to turn it pretty far to get to the right bias level. It also farts out on low notes on the sixth string up to arou d the seventh fret.

Funny that you resurrect this one, I had a similar instance last week, where a tube failed and completely burned the lable off.
That was an EHX 6CA7, the set was out of whack for a while (7ma differentce between the two), so i knew it was gonna end soon
Gotta love the RT2/50 for just turning on a led, letting you replace the stuff and just rocking fine after.

Still having this issue with the bias pot anyone know a replacement part number for it? Randall customer service is nonexistent and only says to take to Randall authorized repair, no thanks I can replace parts myself and save $100 plus (bench fee from closest one was $85 just to look at it!)

Guessing it's a bad biasing pot.