Intermittent tube, poss vibration?

[tref_h]

Hi!

This is an amp mod not FX, so I hope it's ok to ask here...

I have a Trace Elliot Super Tramp Tube.  It's a lovely amp when playing nice.  Basically it's a solid state clean channel, MOSFET power amp and a single ECC83/12AX7 for amplifying element in the lead channel preamp.  Often the lead channel won't work, and then wobbling the amp may bring it back, or re-siting the preamp tube.  This is a pain as you have to un-ship the chassis to get at it.

The preamp tube is mounted on a plastic base, directly on the PCB inside the chassis.  I know the tube itself isn't at fault (no microphony, other tubes = same result).

What I'm considering is getting a new ceramic chassis mount B9A base and screening can and re-siting the tube externally on the chassis.  Does this sound reasonable?  The plan is that the hold down spring in the can will solve any vibration issue and the replacement ceramic base will cure any heat problems in the current plastic item (oldish amp, might have got a bit warm and 'grown' a bit...)

Thanks!

[R.G.]

It's common practice among amp techs to clean, then re-tension tube sockets. You clean them with a pipe cleaner and Caig Laboratories DeOxit 5; you can use other stuff marked "contact cleaner" but Caig's the recognized leader. Then you use a thin, stiff probe of some kind to slightly bend the contacts back into closer contact. An ice pick works very well for this (if anyone remembers what an ice pick is    )

[tref_h]

Isn't an ice pick something you get in your forehead?  ^_^  Whoopee!

Sorry.

I tried contact cleaner, many repetitions of re-insertion and rolling the pins already.  Haven't actually used a probe down there to scrape about, but the cleaner and reps ought to have taken care of any contact corrosion.  Often a hard tap to the right area of the chassis will bring it back too, but I want to actually cure this not just fudge it for a bit.

I'm still holding my theory of poor contacts due to poor choice of mount, poor choice of site or both.

When it's working it's a freaking awesome amp considering it's not pure tube, and I've had lots of proper british valve amps in the past.  I notice that the s/h value of this model is extremely low, usually lower than it's all solid-state, two-channel only sibling.  Maybe inherent un-reliability is the key...

[GibsonGM]

Try re-tensioning the clips inside the socket...I'd put my money on that....

[Cliff Schecht]

It's common practice among amp techs to clean, then re-tension tube sockets. You clean them with a pipe cleaner and Caig Laboratories DeOxit 5; you can use other stuff marked "contact cleaner" but Caig's the recognized leader. Then you use a thin, stiff probe of some kind to slightly bend the contacts back into closer contact. An ice pick works very well for this (if anyone remembers what an ice pick is    )

DeOxit really is great stuff. My dad swears by it for a wide range of applications. Anything that contact cleaner does well, DeOxit does better.