I believe there is a power conditioner you can plug into your outlet to help filter out noise. Perhaps someone on this forum knows of one. Glad to hear your amp sounded ok at practice. :Cheers Dana's blues I use a Furman A210AE. 10 Amp compact power conditioner with auto-resetting voltage protectio...
I cannot complain, I receive an excellent treatment. But if Marshall say that issues are because I used wrong or whatever. I will pay 2 times the amp. It's a combo is full of marks. I have carried it everywhere. I have used it a lot.
Good news. The amp have full warranty. Marshall will fix It.
But I don't know what tubes it's better send to UK. Stock tubes? They are new, I don't use It. A new ones? Or an used ones that they worked until amp blowed HT fuse? The amp don't work with any of them. It blows HT fuse.
I bought It in UK on 17-05-2019. Maybe still in warranty. I asked today to the store. Let's see. I don't know because brexit.
Already got a response from the store (guitarguitar). They will get in touch with Marshall on Tuesday when they reopen to check my warranty terms. Let's see It.
Maybe try to do the mod recommended by Steve... replacing the humdinger by 2 resistors? Yup i would follow Steve's advice and ditch that pot and then see where that puts you. It's really easy replaced It and Install two resistors. But I would like disassemble the board first and take a look on back...