HELP / Strange amp failure : white noise even on standby

[FredPhil]

Hello all

My HT Stage 60 had a very strange behaviour the other day. When powering it on (but still on standby), it made some quite loud white noise.
With standby off, the noise remained, and no sound from the guitar I plugged. No matter what control I used (gain, volume, ...), the white noise kept the same and still no guitar sound.

I brought it to a specialist who'd never seen this kind of behaviour before. He ruled out tube problem, main power... It seems the problem is the power supply for tubes heating. He tried to change an IC (power supply controler it seems) from the main board but to no result.

I'm from France, so we depend on Blackstar Spain who told him that the best would be to send them the main board for analysis or even to replace it. I don't now the delay for such operations, nor the cost of a new board, but either way it would be a costly and probably long process.

Does anyone out there have encountered the same problem? A magical solution would save me money and time!

Thanks in advance
Fred