Mark IV Red Plate Problem

[Mark IX]

does someone has a pic of red plate tubes?

Ithink my mark iv suffer of this problem...I hear random noise thru the speaker when amp is on, even with no guitar cable

the inside of the tube is red (6L6 winged c svetlana all new)

please help...I'm really new to tubes...specially tube problem

 

[Platypus]

Is one tube a *LOT* more red than the others or are they all the same hue?

It will be significantly brighter if you're red plating

 

[Mark IX]

all red to me

 

[Mark IX]

can someone post me a picture of a normal tube on
maybe a 6L6 winged c

pleeez :?

 

[Boogiebabies]

If they were red plating, the fuse would blow. Noise with no guitar plugged in could be from the inputs shorting jack being bent and a noisy preamp tube. The input needs this to short the input to ground, thus no noise. I don't think someone is going to wait long enought to shoot you a picture of catastophic tube failure, it's like asking them to blow the amp up for you.

 

[stokes]

There are large grey structures inside the tube,these are your plates.If they are glowing red you have a problem.If you see orange "dots"at the top or bottom of the plate it is likely your filaments which is normal.Turn the amp on and leave the standby off,you will see the filaments glow,after a couple of minutes put the standby in play mode,if you see the plates start to glow,there is a problem.If you just see the same filament glow you saw in standby mode plug in a guitar and play a few minutes watching for any change in the plate.If it starts to glow turn it off.You cant just pop in any old set of tubes,they must be tubes that are graded to be safe for use in the amp or the bias must be checked to be sure they are safe.

 

[Mark IX]

If they were red plating, the fuse would blow. Noise with no guitar plugged in could be from the inputs shorting jack being bent and a noisy preamp tube. The input needs this to short the input to ground, thus no noise. I don't think someone is going to wait long enought to shoot you a picture of catastophic tube failure, it's like asking them to blow the amp up for you.

Ok, I understad about the pic... :lol:

 

[Mark IX]

There are large grey structures inside the tube,these are your plates.If they are glowing red you have a problem.If you see orange "dots"at the top or bottom of the plate it is likely your filaments which is normal.Turn the amp on and leave the standby off,you will see the filaments glow,after a couple of minutes put the standby in play mode,if you see the plates start to glow,there is a problem.If you just see the same filament glow you saw in standby mode plug in a guitar and play a few minutes watching for any change in the plate.If it starts to glow turn it off.You cant just pop in any old set of tubes,they must be tubes that are graded to be safe for use in the amp or the bias must be checked to be sure they are safe.

the grey structure inside the tubes (so now I know what is a plate , Thanks) are ok...what looks to me different from the stock mesa tubes (Now I use Svetlana Winged C 6L6) is the metal stick inside the plates the are incandescent red...maybe is just because the kind of tube is different, with a different internal structure...I'll try tu put all the stock mesa tubes...maybe a preamp tube become microphonics, and I'll let you know...thanks guys

 

[Mark IX]

Today I've changed all the actual pre tubes with stock mesa...same problem random noise, like interference, sometime they become more intensive after a while they appear with or without the guitar connected but only when on...in stand by everything is quiet...also ?'ve noticed that when I turn on the amp (from standby) the same noise came from the speaker...everytime...tomorrow I'll try with stock mesa power tubes


please need help and suggestion....also a couple of days ago it blow a fuse(never happened before) could be a bad quality fuse? the type is the same...just a different brand...could be the fuse microphonics? :roll:

 

[Octavarius]

Today I've changed all the actual pre tubes with stock mesa...same problem random noise, like interference, sometime they become more intensive after a while they appear with or without the guitar connected but only when on...in stand by everything is quiet...also ?'ve noticed that when I turn on the amp (from standby) the same noise came from the speaker...everytime...tomorrow I'll try with stock mesa power tubes


please need help and suggestion....also a couple of days ago it blow a fuse(never happened before) could be a bad quality fuse? the type is the same...just a different brand...could be the fuse microphonics? :roll:

The amp is grounded, right?

 

[Mark IX]

yes...i think so...how can i know...the mine is 2006 version, european...has no ground lift

 

[Buddy]

If my amp started making random noises ....
I'd :
Turn on amp , plug in cord , no guitar .( the cord is good right ? )
Tap , turn , and spin the pots . ANY noise is unacceptable .
No change ? not them .
Grab chopstick . start tapping pre tubes gently . Squeals ? honks ? Increase in interference ? Brain melting , howling screams of agony ? Pre tubes or sockets . ( could be bad component inside the amp ) Try same with power tubes .
No change ? hmmmm. Maybe time to open that baby up .
Carefully .

 

[Mark IX]

good cable I've tryed 3 georg L planet wave van de hull...the noise appear only sometime for a while like an olp LP turntable crackle...and everytime I pass from standby to on on every channel...I've changed the 6l6 olso...no noise from any tube no one

What I know is that a I've played a couple of gig's this summer with a lot of moisture and were the power was in the red zone of my Furman POwer Factor (between 190 and 200, the standard for europe is 230) the tube becomes very hot when is one you can't touch them without hurt yourself

If I open It what can I look for

 

[metalblitz84]

I can't get the link to work

 

[Buddy]

Guiseppe ,
At this point I'd check all the power/simul tube switches with the impact(minor) test ... Are you getting the noise while playing ,certain notes or only when the amp is undriven ?

Are you familiar with working on these thing's ? Research .

I would not suggest opening the amp unless you are sure all voltage is dissipated . It can be perilous in there .

 

[Mark IX]

Guiseppe ,
At this point I'd check all the power/simul tube switches with the impact(minor) test

1What is this?

... Are you getting the noise while playing ,certain notes or only when the amp is undriven ?

2 I get this noise randomly...for few seconds...and in this momentes I've tryed to change channels...with no difference from a distorted one to a clean one, with or without the guitar connected
if I put the master higer I've an higher noise and I get this crackle sound every time i pass from standby to on




Are you familiar with working on these thing's ? Research .

3 no no and my amp is in warranty I don't wanna loose it

I would not suggest opening the amp unless you are sure all voltage is dissipated . It can be perilous in there .

 

[Buddy]

Impact test = whack the cabinet near the switch .
If there is a loose connection or dirt in the switch ,the noise will present itself . Then you can get in there with some contact cleaner spray . This requires pulling the chassis . Normally this will not void the warranty . Clean all tube sockets , input and effects loop jacks while your in there . You dont want to soak things too much , a quick spray and work the switch/pot 20 +times till the noise goes away . You can also gently wiggle the tubes and see if you can cause the noise .

 

[Octavarius]

yes...i think so...how can i know...the mine is 2006 version, european...has no ground lift

Nah, it's probably not a ground issue, so nevermind. But for your information it means that the amp is plugged into a three-prong socket. Hot, cold and ground. It could also be one of those new sockets with metal plates along each side instead of the third prong in the middle.

This is weird. If it was an old amp, I'd guess caps, but yours is practically new. Does the noise come randomly by itself or when you do something? Check all your cables and connections. Power cable too. Is it hooked up with a power conditioner? Try that. Also try changing controls and whatnot to see if you can recreate the noise, like Buddy said.

Also try swapping the preamp tubes around. If you have a spare new tube, change it with each one at a time to see if that helps. Put in good properly matched (Mesa's) power tubes too. The fuse could have blown because of poor matching between the Svetlana's and the amps fixed bias. And no, there's no such thing as fuse microphonics as it's not in the signal path. The fuse is there to cut the electric path when a tube shorts etc.

 

[Mark IX]

I think we are near the solution...here what happens

turn on the amp in standby lead channel (the lead channel is just louder) plug in a cord (with or without guitar) tur on the amp...remove the jack and the noise is re-create

similar but short happens everytime I pass from stand-by to On (with or without a cord...in every channel same noise...with or without a guitar connected)


Thanks

 

[Octavarius]

I think we are near the solution...here what happens

turn on the amp in standby lead channel (the lead channel is just louder) plug in a cord (with or without guitar) tur on the amp...remove the jack and the noise is re-create

similar but short happens everytime I pass from stand-by to On (with or without a cord...in every channel same noise...with or without a guitar connected)


Thanks

Ok, but does it only happen when you flick the standby switch? Also try wiggling the cord in the input jack.