#1
I just replaced all of my tubes except for one of the preamp ones.

Everything is in properly, I double checked.

Switch on the amp, the tubes start glowing as they should.

Plug in, and the guitar is at about half volume so I knew something wasn't right, and it made faint popping sounds so I turned it off after about 5 seconds.

Had a look around the back and I could smell burning....


Can anyone shed light on this or have I just wasted £90 on new tubes only for them to break straight away?
Last edited by Random3 at Jan 20, 2012,
#4
Did you touch the tubes witb your bare hands? Or allow dust to get in/on them. If it smells like burnt plastic highly possible theres a problem
#6
Try some of the old preamp tubes in place of the old one still in there. It may have been the dud all along.
Touching the tubes causes no problems whatsoever. I bit of a smell when they are new isn't unusual. They can have a bit of filth on them outa the box.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#7
Quote by Cathbard
Try some of the old preamp tubes in place of the old one still in there. It may have been the dud all along.



There was no dud, I was just upgrading the tubes. I wasn't changing them because there was a problem with one of them.
#8
Vacuum tubes are not prone to damage like halogen lamps in cars. I handle the tubes all the time with my fingers.

That burning smell, if it is anything like when my amp went POP! FZZZZZZZT!, I'mma gonna guess the screen grid resistors just went.

Mine is a MIG 50 which uses 6L6 tubes, and the ones that were in there were JJ's. One of them shorted out and took out the grid resistors.
#10
Try cleaning the sockets then. Spray some contact cleaner on the tube pins and work them in and out of the socket a few times.

I would also take one of your old tubes and systematically try it in every position. It is possible to have dud new tubes. You have to do some systematic diagnostics. You say the old ones worked ok so there is your test tube. Now have at it.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#12
You have all the new tubes in. Leave them in and try one of the old tubes in each position where you have the new ones systematically and test it each time. You are trying to test the effect of each one in isolation, so only do one at a time. Careful you don't burn your fingers, use a rag.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#15
So you think you have a broken fuse holder spring? Replace the entire fuse holder.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#16
I've managed to put the fuse back where it was but the amp still isn't powering on at all. No lights, nothing,


Edit: Ok now it has turned on. I shall proceed with tube testing.

EDIT: Now I am confused. The amp is on and there is no smell. Had it on for about 2-3 minutes with nothing plugged in. Every tube was lighting up as it should. Then it started making input jack noises, like touching the end of a cable even though there is no cable plugged in. So I turned it off and the smell came back though no where near as bad as before.


This was with all the new tubes, I decided to switch on once more to check and see if the problem resolved itself. Any ideas?
Last edited by Random3 at Jan 20, 2012,
#17
Ok slight update.

Fuse problem is fixed.

Amp sounds fine.

However after being plugged in and switched on for a few minutes the burning smell comes back.


EDIT: Problem seems to have resolved itself

Thanks for the help anyway.
Last edited by Random3 at Jan 20, 2012,
#18
There can be all sorts of things in an amp that can smell; bugs, dirt, etc. Fair bit of convection in there too so shit can move around. Watch closely for smoke and see if you can identify where it is coming from. If it isn't an actual component burning I wouldn't be too concerned.
Just be thankful it isn't a Bugera about to burn down your house.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#19
Quote by Cathbard
There can be all sorts of things in an amp that can smell; bugs, dirt, etc. Fair bit of convection in there too so shit can move around. Watch closely for smoke and see if you can identify where it is coming from. If it isn't an actual component burning I wouldn't be too concerned.
Just be thankful it isn't a Bugera about to burn down your house.




Cheers man!