Marshall 8080-Channel select button problem

[tommy12]

Hi there,

I have a Marshall Valvestate 80v - Model 8080.
The channel select button from Normal channel To Boost channel is sometimes jumping from one to another, it usualy happens when i play some time (Maybe heat problem ?). But it usualy happens from Clean to Boost as long as i can remember.

Here is an image of the amp and this button.

An externally hosted image should be here but it was not working when we last tested it.

What can be the problem ?

Thanks

Tommy

 

[Enzo]

The switch contacts can be dirty, the solder under the switch can be cracked, the switch can be mechanically failing, there can be a problem with the power supply to that circuit. TR1, TR2 could be going leaky.

 

[tommy12]

Thanks,
I gave the amp to a technician and he said that every thing is O.K. with this switch, but i don't think he is a good technician.
I already paid him and i have warranty so i'm hoping he know how to repair it.
I asked the question in order to know better and if it's necessary i'll ask him if he checked this options.

I already have regrets for not going to a well known technician.

Thanks for helping

Tommy