OK i have posted this question on another site already and found the response very disappointing hopefully this might be the right place to be.

And hey to anyone!! Yep i know my first mistake was buying one of these amps in the first place still i will never make that mistake again and in fact Marshall can stick all their amps where the sun don't shine because i had a lot of trust in them so i will take my money and my business elsewhere!
But i still need to get this amp sorted so any body please any answers or if you have had the same problem i would like to know! The valvestate basically works on BullS*** in that the valve in this amp is useless and sits there not doing really very much except for Marshall to make a nice bit of cash from a concept which really is totally bull.
I have a Marshall Valvestate AVT275 combo which has developed a fault causing the amp to lose all sound but all lights stay lit. As soon as the tube was replaced all was ok but it seems that there was nothing wrong with the first tube and somewhere here is a very strange fault.
The amp if fiddled about with like a new tube put in will work from anything of say 2 minutes or all day and then lose all sound. I have taken this amp to be repaired and all the obvious things according to the engineer was replaced but still the fault exists?
He has finally thrown the towel in and given up so i need to find anyone who has experienced the same problem and how the problem was rectified.
Yes i can send this amp back to Marshall but they would probably find themselves in the same position and end up disposing of the electronics inside altogether. This amp is less then about two years old it has been gigged but i am very carefull how it is transported. The amp has not been dropped, Kicked.
In fact i had performed a five hour gig using this amp and had been using it for three or four hours before and there was not any indication of anything being wrong.
The amp was stored after the gig and was not played until a week later when i found this oddball fault.
This has put me right off of Marshall amps i have had some very good amps in the past which i sell off after about three years of use but this Marshall amp is very disoppointing.
Any help please?

what are you trying to ask?

OK my question is this. Can anybody help me in nailing this problem i have with my Marshall AVT275 Valvestate amp. Or maybe someone out there has experienced the same problem with their amp?
The problem:

The amp is switched on all lights on and the pedal board lit up guitar plugged in i go to play no sound nothing at all? Except all the lights lit up on the amp but no sound.
I fitted a new Tube suspicious that this was causing the problem. On fitting a new tube the amp worked fantastic then the sound went went off again after about 7 minutes.

The amp was taken to an engineer who stated that he had the amp working with no tube inside at all. He repaired a number of loose solder joints etc then asked me to collect it. He had this amp on test no problems showing.
I collected the amp took it home plugged in brilliant i had sound.
However 2 minutes the sound went off again. I took the amp back but after a number of weeks the engineer is at a loss as to what the problem is.
He replaced all what could have caused this problem but still the problem was there. He has finally thrown the towel in now so i need to find someone who could repair this amp or at least tell me what it could be that is causing this problem.
Or someone who has a similar experience and have since repaired your amp.
I would like to hear from anyone who could be genuinely of assistance to me.

Sounds like a poweramp failure.

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Does it keep blowing fuses somewhere? Maybe a loose connection is causing it to short out all the time. Sounds like a crap tech that can't solve the problem, take it somewhere else.

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The guy that was looking at this amp is very good and i always use him for any repairs i need. The problem is that the fault we are dealing with is absolutely stupid because you could have the amp on for a week and nothing will happen or maybe have the amp on for 1 minute and the sound will go off.The engineer obviously has other work to get on with and had spent a good deal of time trying to sort this problem out.
I have had the amp back since and so far it has been on now three hours and is still working with no problems at all and i have really hammered it with very loud distortion and still it refuses to switch off this is how frustrating this problem is!
I have now had to purchase another amp set up for our gigs as you can bet that i will turn up for a gig and the amp will switch off half way through a solo You know its going to happen!! So i aint taking any chances.
I am taking the Marshall to band practice Sunday so i will really put through something to see if the sound will go off again.
Valvestate especially the 275 i have been told is a very good amp unfortunately i have the duff one? But then again thats typical

Sounds dumb, but maybe its a faulty on-off switch? I dunno if you say the guy is a pro tech, then I haven't got much chance of identifying the problem. Get in contact with marshall and see what they say. Also post this over on the Marshall AMp forum. IF you decide to keep the amp then I'll give you a tip: change the speakers. I did on my AVT100 and it made a huge difference.

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Thanks for the answer.
As for the Marshall amp forums i would post this on there if i could find the link which allows me to register.
Amp still working fine?? no cut out as yet.
I do not wish to change the speakers as these are Celestion probably the most best speaker around.
I have just purchased a Beringer stack 4x4 BG142H and a GMX1200H Vtone
This would have been a Marshall full stack but as for the problems on the AVT i thought no chance i am buying another Marshall amp ever!

Nah trust me, those speakers may be celestions, but they are the worst piece of crap ever put into an amp. 'Specially developed' my ass. Just another sign of Marshall cutting corners. Oh and the register button is in the top right-hand corner, its a little button under 'PM'.

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