Fender Super Champ X2 add a standby switch?

[mresistor]

Guy wants to add a standy switch to his SuperChamp X2 pcb board amp.  Has anyone here ever done this or similar? I'm thinking this isn't really a good candidate for one. I guess I could interrupt B+ but I'm futher looking at the screen and inverter. Also don't know if I have enough room on the panel.  What do you guys think?


Heres the service manual link


http://music-electronics-forum.com/attachments/30019d1407933697-fender-super-champ-x2-service-manual.pdf

[mresistor]

What about breaking the ground connection to the power tubes?

[Colas LeGrippa]

just put a switch on the pt center tap to gnd


Colas

[mresistor]

Thank you Colas - wouldn't that be just like another ON/OFF switch? in that it would shut off all the power in the amp, bias, and all the nodes.


This amp doesn't have a center tap on the HV ..  it's got a solid state rectifier, but the rectifier has two ground points that could be interrupted.  The HV , screens and the PI are fed off this winding.


So I'm thinking interrupting either the grounds on the HV rectifier or the ground to the power tube cathodes.  Which would be better? The ground to the power tube cathodes would entail a pretty simple switch.
I'm wondering if that is OK to suddenly turn on the tubes like that..  Would it be a shock to them and detrimental or would it be safe?

Anyone?

[SILVERGUN]

Since there is no center tap on the HV winding I'd interrupt P9 or P10 like the snip from Merlin's site

[mresistor]

Thanks SG  looks like a good idea.. 

[mresistor]

I suppose I could use a standard Fender Standby switch  ( carling ) ..  and tie on the 47K 2 watt resistor.. 

[mresistor]

Well as luck would have it I don't have a 47K 2 watt resistor.. closest I have is 18K .

[sluckey]

It will work just fine with no resistor.

[mresistor]

Thanks Sluckey - that's good news. Also  think I'll use a mini switch which requires a smaller hole and is smaller in size but has the same rating as the Carling.

[mresistor]

It worked perfectly.   Thanks for the help.

[PRR]

> has the same rating as the Carling.

The Carling is not rated for 385V DC.

We "know it will handle it" from 50+ years of experience with Carling's over-built clunkers.

Are you still confident about that mini-switch?

(Do you care? Is this "guy" a good customer or friend?)

A "Mute" (but call it stand-by) can be done with about no load on the switch. HV stays up, but that should not hurt tubes, unless the standby goes on for many weeks.

[mresistor]

Thanks PRR -  I looked at other ways to do this and invariably they involve modifying or messing with the main PCB. I think the switch will be OK. Interrupting the ground of the power tube cathodes would have been a good way too, right? only 40ma at that point.