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Tube Blown, Or Problem? (dt25)


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#1 thatoneguy759

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Posted 15 April 2014 - 06:05 AM

Hey, overtime I noticed a popping sound was starting to occur in my amp. A couple days ago I found that whenever the popping sound occurred, plasma appeared in the tubes, sort of like something electricity zapped across the tube. I have also noticed that that tube was much hotter than the others, but later that day it popped one more time, and then the amp powered off, and it would not turn back on. Is this just a tube blowing out? Or something else. As far as it being a short, the plasma, or electricity was not like a lighting bolt, it was more like a purple-blueish glowing cloud in the tube. This is my first tube amp, and it has been a year since I got, I have not changed the tubes since I got it.


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#2 Brazzy

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Posted 15 April 2014 - 06:10 AM

Sounds like the tube leaked. I think you get that color you describe when the tube loses it's seal. I've had the snap, cracle, pops, and fizz's in my DT50 a few months ago and now it needs service after 5 months of home use. My tubes don't have any signs of problem in fact it will come on and work a little while before going cold again, my problem seems intermittent.


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I mostly play at home  and am always having fun learning how to play guitar so when I post a reply to try and help give ideas you know where I'm coming from. Rock-On!! Oh, and if I don't respond promptly I'm probably playing guitar or my computer locked up from multitasking 'cause I'm using Gear Box, HD500 Edit, Audacity and tab filled browsers all at the same time, Hahahaaaa. Surprisingly enough my 'puter handles the load more times than not. Lastly I'm not a salesman, I'm not trying to sell anyone anything here. "Riffcasts Riffworld" "RiffRumble Entry" "Shifftie" "M.O.S.U.A Two" "Bass Catszz" "Blasted Runtime Error I" "Match 30" "The Playlist"
 

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#3 radatats

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Posted 15 April 2014 - 06:15 AM

sure sounds like tubes to me!  Once that popping starts, that is an automatic tube order...  before something more serious occurs as the tube blows out.

 

A tube is sort of like a light bulb.  It has filaments inside that conduct electricity and heat up.  Over time they simply wear out or burn out and the filaments can break and short out.  You don't want that to happen as that is when other parts get taken out too...  Best to simply replace them at the first sign of trouble.  Definitely stop playing through it once it starts to give problems until it is sorted out...


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#4 Brazzy

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Posted 15 April 2014 - 06:27 AM

sure sounds like tubes to me!  Once that popping starts, that is an automatic tube order...  before something more serious occurs as the tube blows out.

 

A tube is sort of like a light bulb.  It has filaments inside that conduct electricity and heat up.  Over time they simply wear out or burn out and the filaments can break and short out.  You don't want that to happen as that is when other parts get taken out too...  Best to simply replace them at the first sign of trouble.  Definitely stop playing through it once it starts to give problems until it is sorted out...

 

I'm starting to beleive the underlined to be gospel in the tube amp world. Amen to that Brother!!!


Edited by Brazzy, 15 April 2014 - 12:32 PM.

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I mostly play at home  and am always having fun learning how to play guitar so when I post a reply to try and help give ideas you know where I'm coming from. Rock-On!! Oh, and if I don't respond promptly I'm probably playing guitar or my computer locked up from multitasking 'cause I'm using Gear Box, HD500 Edit, Audacity and tab filled browsers all at the same time, Hahahaaaa. Surprisingly enough my 'puter handles the load more times than not. Lastly I'm not a salesman, I'm not trying to sell anyone anything here. "Riffcasts Riffworld" "RiffRumble Entry" "Shifftie" "M.O.S.U.A Two" "Bass Catszz" "Blasted Runtime Error I" "Match 30" "The Playlist"
 

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#5 thatoneguy759

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Posted 15 April 2014 - 06:31 AM

So I removed all the tubes, the amp won't turn on. I check the main fuse to, and its still good. I think that means it may not be the tubes... or is that normal if you remove the tubes?


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#6 radatats

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Posted 15 April 2014 - 06:40 AM

So I removed all the tubes, the amp won't turn on. I check the main fuse to, and its still good. I think that means it may not be the tubes... or is that normal if you remove the tubes?

 

First and foremost, there are voltages in a tube amp that can kill you dead even when not plugged in or turned on

 

If you do not know what you are doing, keep your hands out of the amp and take it to a qualified service technician.

 

Do not try to troubleshoot this on your own.  You made a significant investment when you bought this gear and you are well advised to spend the few dollars to maintain it properly.

 

Second, yes it's normal.  Get the power tubes replaced.  The 12AX7 is a phase inverter and can be replaced, but generally lasts much longer than the power tubes. 


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#7 egkor

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Posted 15 April 2014 - 07:13 AM

It sounds to me like a power tube went out, and that blew a fuse.

As I understand it, there is more than one fuse. I will have to let someone with more knowledge expand on that.

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#8 stumblinman

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Posted 15 April 2014 - 10:33 AM

There are two fuses. One below the power cord plug on the back of the amp, and another slightly above and to the right. Check both with a meter. They are designed to blow to prevent damage to other components. I hope for your sake they did their job since you didn't stop playing when you saw lightning in your tubes.
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#9 thatoneguy759

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Posted 16 April 2014 - 10:32 AM

I stopped playing, and tried to see what was going on, 30 sec latter is when it blew. Now that I think about it it probably was a leaky tube, otherwise their would be no gas inside the tube to create the plasma I saw. Also i found some "ash" in that tube I pulled out.


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#10 stumblinman

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Posted 16 April 2014 - 11:04 AM

Catastrophic failures are always scary. I've had a few slow fades where you knew what was coming and a few "pop snap silence" incidents, and those always freak me out.

I stopped playing, and tried to see what was going on, 30 sec latter is when it blew. Now that I think about it it probably was a leaky tube, otherwise their would be no gas inside the tube to create the plasma I saw. Also i found some "ash" in that tube I pulled out.


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#11 thatoneguy759

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Posted 16 April 2014 - 02:22 PM

I just checked the main fuse, its blown. The tube protection fuse is still good though. (Thank you fuse for saving an investment!) So my next question is does this mean it might not be the tube?


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#12 TheRealZap

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Posted 16 April 2014 - 02:24 PM

probably doesnt mean that....

fuse blew for a reason....

basically to protect the rest of the electronics from whatever wasn't right.....

most likely it's still not right...

 

I just checked the main fuse, which blew. (Thank you fuse for saving an investment!) So my next question is does this mean it might not be the tube?


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#13 radatats

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Posted 16 April 2014 - 02:35 PM

I just checked the main fuse, its blown. The tube protection fuse is still good though. (Thank you fuse for saving an investment!) So my next question is does this mean it might not be the tube?

 

ABSOLUTELY NOT!  you already described the tube as having "ash" in it... the tube blew and shorted out causing the fuse to blow which hopefully prevented other more serious damage.  As I already stated, take it to a service center or a qualified tech.  You are risking further damage and personal injury or death mucking about with gear you are unfamiliar with.  Please follow this simple advice...  But, its your life and money...


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#14 stumblinman

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Posted 16 April 2014 - 03:32 PM

I lost my main fuse when a tube blew on my dt25. Sounds about right to me.

I just checked the main fuse, its blown. The tube protection fuse is still good though. (Thank you fuse for saving an investment!) So my next question is does this mean it might not be the tube?


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#15 thatoneguy759

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Posted 24 April 2014 - 01:19 PM

New tubes = fixed, for anyone still viewing this post


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#16 stumblinman

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Posted 24 April 2014 - 02:24 PM

Glad to hear it. 👍

New tubes = fixed, for anyone still viewing this post


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