Marshall Bass Guitar Amplifier MB450H schematics

[sirNemanjapro]

I'm having a problem with this Marshall MB450H amp. It seems that there is something wrong with the power line coming to the tube (ECC83 pre-amp valve (Classic channel)), not the tube itself. I've replaced the parts that I've could and knew, but the problem remains.

Can anyone please share a scheme for MB450H or at least point me where to look?

or

If possible I would like just a scheme for pre-amp for ECC83.
The problem is that the signal is coming through, but it's very weak.

[Anks]

When you say weak were are you measuring and what are the voltages on the pins of the ecc83

[fleuroman]

try youtubing Daves world of fun stuff, contact him and ask if he might know where you can get schematics for it, he mainly does base guitars but I've seen him do a few amps