JMC 800 Artist (2203) with noise

[rbotn]

Help!
I have a Marshall JCM 800 who are rather noisy at High input. I post a video here where you can hear the noise when I put in the guitar at high input. I have tried with 6,3 DC filament for the two preamp tubes, no result. I have change the jack input set at the front. In the video you can see the cables from the input jacks to the tube. They are grounded at the potmeter.

 

[AML]

Can't view the video

 

[rbotn]

Can't view the video

Sorry. had forgotten to set to Publish. Thanx.

 

[anitoli]

Ground issue?
Try changing tubes?
Try it with the PI removed, still noisy?
Single coil guitar?

 

[rbotn]

Ground issue?
Try changing tubes?
Try it with the PI removed, still noisy?
Single coil guitar?

Yes. I have also a suspicion about ground, but it looks like every groundpoint is ok.
I have changed the preamp tubes. No difference
When I remove the first preamp tube, the noise is almost gone.
Even when the guitar volume is totally down, the noise is still the same.