a15Mk1 ground problem

Hi,
I think my brand new A15Mk1 has some ground problem (probably due to a bad assembly )
It's a bit noisy, but if I touch the shield on the pre amp tubes (expecially 3rd and 2nd tube (as in the schematic)) it becomes silent as it should be...
What can I do to avoid that hum and hiss? (which soldering I have to carefully check and double check again? any other hint)...of course as I release the shield the amp is again noisy :(...
Thanks again!
Krusty

Re: a15Mk1 ground problem

Hi Mad,
thanks for the answer...
the chassis is connected to eath.
The signal ground is connected to earth throug the chassis (removing some paint on it) (as specified in revision 1.4 no 100 Ohm resistor between ground and earth) and if I measure resistance between star ground and earth I have 0 Ohm.
Probably the problem is the painting (deluxe version)...that Insulate the shield of the tube on the upper part of the chassis....
Do You think I have to remove paint on the exterior side of the chassis just under the socket tube??
what do you mean with "Are the tube sockets grounded?"
The tube sockets are grounded as you mean that the center pin of the socket of the tube 1, 2 and 3 is connected to ground via green wire and then to the star ground point!
Thanks again
Krusty.

P.S. any news about gain pot and volume issue (there is a topic on the forum regarding this)?

Re: a15Mk1 ground problem

Thanks, but you did not answer to my questions about paint on deluxe version chassis...
I have already tried in other wall plug and the noise is always present!