Fault with Blackstar HT100 Metal Head Overdrive channels

[rkrjaymz]

I was playing through a Blackstar HT100 Head and a 4x12 cabinet for a couple of months. Now that I have stopped playing due to a faulty HT100 head.

I used to play super loud in an industrial area and can crank the OD1 / OD2 channels to about 75% gain and volume. That is annoyingly loud as I need to keep up with the loud band group I am in. It was all so great.

However, on May 14th, 2021, the OD1/OD2 started failing. They work but not properly. The overdrive channels are spitting weird fuzzy tones like an X wing in Star Wars on fire and the volume/gain drops lowly and then suddenly returns. It's so uncomfortable to hear that. So the distortion is not smooth and not great anymore. The gain diminishes for a few seconds and returns louder. Normally, I will plug my guitar direct into the amp head. I don't prefer pedals too. So it's a problem with the HT100.

Yesterday, I changed all the 4 stock 6L6 tubes power tubes, and swapped the 2 x ECC83 and 1 x ECC82 to new matched pairs of JJ tubes. I spent close to $200 on these new tubes. Now when I am gigging with the head, the same old situation happens when the tubes heat up after 15 minutes.

The OD1 and OD2 channels are still bad. So tubes/valves are not a prime suspect here.

Any advice or help would be greatly appreciated. I am in Singapore and there is a Blackstar agent and dealer that sells these products but I think they may not offer any help. I'll try anyway. The head I bought is a used amp head so I don’t think they will offer help. I love this HT100 to bits and pieces. I got crazy over it’s cranked tone but now I am so sad it isn’t working in the way it should. Clean channel is still good.

Did anyone come across such a problem with OD1 and OD2 channels? Is it a common issue?

Please help. Thank you

[iivel]

I have exactly the same problem. After the Amp has warmed up, sound suddendly goes fizzy and dies completely away, just to come back a few seconds later in another loudnes/gain structure. then it happens every few minutes, intervalls increasing.
Does anyone know hov this problem can be solved? Some part(s) apperantly to have gotten very temparature sensitive!
I am capable of soldering and servicing the amp by myself, so any advice which part might possibly needs replacement is welcome (I have already re-soldered some weak soldering contacts on the main board, with no effect). All tubes new.

Cheers,
Michael