Problems on Marshall Valvestate vs100 (Head) - tha amp hums and no sound

[morferic]

Hi all,
I'm a newby of this forum!
I've a problem on my Marshall Valvestate vs100 Head amplifier.
My Amp all at once began to hum and, if I connect my guitar, only at 100% of volume I can hear something (very very low).
If I adjust the volume, the noise also changes.
I've opened the chassis and I see that when I turn on the amp the tube (a 12ax7/ecc83) makes a blaze/flash (..I'm not english and I don't know how translate "bright light", sorry: confused..After few seconds the light fades down to a "normal" tube light.
Is this normal?
Maybe I must change the tube?

Anyone knows what kind of problem my amp have?

Than you so much!

Eric R.

[andyjazz]

yes, change the tube. You can get a Chinese 12ax7 for less than $10 US. worth a try

[Krwkka]

If the tube is the EI brand, the flash is normal.

[morferic]

Thank you all for the replies!
I'll try to replace the tube to check if the problem is in it (maybe my ampeg J12R has a 12ax7...).
@ Krwkka: no the tube is an original Marshall. I don't know if the flash is a problem...I can't find nothing in internet about this!
Thank you all!

Eric R.

[morferic]

Problems on Marshall Valvestate vs100 (Head) - tha amp hums and no sound [SOLVED]

Hi all!
I've replace the "Marshall" tube with a "Sovtek" one but nothing happens...
Hopeless, I've decided to check the welds and i've found many cold ones and the guitar input completely unsoldered.
I've replaced all the bad welds and now my amp is like new one!
The wise said: "always check the welds, before check the tube!".

P.S.: @ Krwkka: On the tube is write "Marshall" but probably the tube is an EI one ..the flash is normal, because the tube works well...with my sovtek I have seen no flash (but the sovtek one is much brighter)!

[Krwkka]

I'm happy that you have your baby back! Good job!!