Marshall Valvsestate Problem - Power but no lights or sound

[XxRoadHogxX]

Hi Guys,

Amp is a Marshall Valvestate AVT150.

Before asking the question I have sifted through to see if this has been answered and i can only find something similar but not the same.

First of all, I am brand new to Marshall and Valve amps and I have only just purchased this is really good condition.

It worked perfectly for the first two days and just this evening I moved it upstairs carefully and now it doesn't work.

When I turn the power on, you can he the amp kick in the a slight thud and you can hear a very quiet humming of the speaker but apart from the red on/off switch, none of the lights on the panel light up and no sound comes from a guitar or from touching the end of the jack cable.

Any ideas what this could be? I have been told by a friend who has done a lot of work on his, that if it was the valve, it would still work it just wouldn't sound right.

I have done voltage checks from the transformer to the fuse. and checked the fuse - all fine there is power to the main board that has the Valve on it.

The fan doesn't run, I don't know if it is supposed to all the time or if it should only run when it gets hot?

Also the Valve doesn't glow, again this may be due to the heat sync/chip if this is what has gone?

Does anybody have any idea's where to start?

Please forgive any "Newbie" questions, i have played for almost 10 years but I have never really got in to depths of amps until now so this is all new to me.

Also I don't have the manual or any diagrams.

Any help would be much appreciated, I am really enjoying this amp and cant wait to get it up and running again

Thanks

[Stevem]

[Stevem]

These amps need the fan to run or the output IC packs go outs to lunch when they get hot enough, sometimes with out taking out the fuse.
In a darkened room you should see that 12ax7 tubes filament light up if the tube and it's power supply section are ok.
These amps also have a mute circuit that fails, the circuit stops the amp from making a turn on and shut down thump noise out thru the speakers.
Does the headphone jack work, if not you do have a problem somewhere in the preamp section or power supply.
In the mute circuit there is a transistor and or a Zener diode that fails, you can just clip out the transistor from the top side of the board if you do not mind a small popping sound out thru the speaker when you turn the amp off.
I would suggest you take the amp to a pro for its repair!