Epiphone Constellation V Amp - Need Power Switch

[CoopDaKill]

Hi. I have a mid 60's Epiphone Constellation V tube amp. The power switch is busted and I need to find a replacement. The only marking on the switch is SW78A. I found a rotary switch on the Bay, would this work?
http://pages.ebay.com/link/?nav=item...d=200611893863

[52 Bill]

Hi. I have a mid 60's Epiphone Constellation V tube amp. The power switch is busted and I need to find a replacement. The only marking on the switch is SW78A. I found a rotary switch on the Bay, would this work?
http://pages.ebay.com/link/?nav=item...d=200611893863

I couldn't get your link to work.

What is wrong with the original one?

[CoopDaKill]

The middle part broke. Fell apart. Dry Rotted. I'm looking at a
4-pole-5-position-4P-5T-Ceramic-Rotary-Switch-RF-Power

4 Pole 5 Position 4P 5T Ceramic Rotary Switch RF Power | eBay

[52 Bill]

They don't have any ratings listed, but it will probably work as well as the original one. You might be able to modify the stop to make it into a 4 position switch.

The other problem is the shaft is different and the old knob won't work.

[CoopDaKill]

Thanks 52 Bill. I think I'll give it a shot. I've never rewired a switch like this, so I may call upon you guys for guidance. thank you so much for your help.

[Chuck H]

For safety it should be best to include a grounded power cord and snip out C18.

[52 Bill]

Good point, and if the contacts seem too flimsy, you can use the set that were used for the ground reverse to parallel one of the other functions.

This switch would probably be a good one for R.G's Vox power switch/relay circuit.

[TimmyP1955]

On the schematic I have, the switch is only a 2 pole, 3 position (mains open, HT open; mains closed, HT open; mains closed, HT closed).

Unless you like to use the Standby switch as a mute, you don't need the standby function. (I prefer starting with an amp at 0 volume, in which case the standby is of no importance.) That will save a pole and position. So all you need is a SPST. I'd consider a toggle.

You should also eliminate the polarity switch and the cap.

Connect the mains lead ground wire to the chassis. Rewire the mains lead so the live routes to the fuse post, which goes to the switch, which goes to the PT. The neutral of course goes right to the other lead of the PT.

[Chuck H]

I thought the same thing. I held my tongue figuring there was some priority on maintaining stock operation. But I totally agree. Retrodesign a toggle into the circuit.

[52 Bill]

R.G. designed a replacement for the Thomas Organ power switch that could be modded to work for this amp.

The schematic is posted in the first post. The switch turns on and off the ac power, disconnects the B+ for standby, changes the ground cap polarity and switches on and off the standby and operate pilot lamps. By removing the ground cap and adding a 3-wire cord, the switch can be a 3 pole, 3 throw with OFF/Standby/Operate positions.