Which Rotary Switch?

[retrorod]

I am having to replace a rotary OFF-STANDBY-ON switch on a vintage Premier amp. I am looking at the PH-600 switch that AES sells...
P-H600
Catalog Page 68

Switch - Rotary, 1 Pole, 3 Position
Solid 1/4" Shaft, 6A 125VAC, 0.39" bushing diameter.It is a non-shorting switch. Would that be the correct one for this function, or do I need a shorting switch?
Besides physical size limitations, is there more to consider for a replacement?
Thanks, Rod

[Enzo]

What are the attributes of the old switch? Is it 1 pole 3 positions? Or is it two or three poles 3 positions. 1P3P doesn;t sound like it would be what you need. In most standby systems, one part of the switch turns the main AC on, then a separate part of the switch turns the B+ on.

DO you know what shorting and non-shorting mean?

A shorting switch is one that connects the moving pole to the next contact before breaking contact with the previous contact. SO for a moment the two are shorted together. Generally, power switches are not shorting.

Can you link to or post the schematic for the amp, so we can see what they did?

[retrorod]

I do not have the amp in my posession right now to get a visual again. This is as close to a schematic as I can find.....
http://schematicheaven.com/bargainbi...60_bassamp.pdf
Not sure if it helps. I don,t understand the one pole , two pole thing as applied to a power switch. I,m hoping to get one ordered before I get the amp back in my possession, Thanks, Rod

[Enzo]

That schematic is no help, it doesn;t have a standby function.

A pole is a movable contact. In a simple switch it is the common connection. IN a 1 pole three position switch, the pole terminal can be connected to one of three different terminals by turning the switch. Assuming we leave the end one unwired for OFF, that leaves two other positions. If you have the AC power coming into the switch to the pole terminal, then the switch can select OFF, or it can connect the AC to one of the two remaining terminals.

If you wanted a switch that was OFF, then turned power on in positions 2 and 3, then wire 2 and 3 together and from there on into the amp.. Now whenever the switch is set to 2 or 3, AC power flows through. Then standby usually turns B+ voltage off an on. But B+ is high voltage DC, and no related electrically to teh AC power. So we need a separate switch section. SO a two pole rotary switch has two identical sections just like the signle one described above. One section we wire for the AC power as described. The new second section has the B+ wired to its pol, and then only terminal 3 on that section is wired to the rest of the amp.

SO combining the two, we find OFF ( position 1) means everything is off. Thehn in position 2 only teh AC is on, and finally in position 3, the AC is on AND the B+ is on.

[retrorod]

Thanks for the explanation! So if I follow you right....I would need a 2 pole non-shorting 3 position (6 total) adding both poles ....switch, to perform the OFF/STANDBY/ON function?

[Enzo]

Well, assuming what I see in my head. The amp itself may have other ideas, but I;d say you need at least that.

You don;t want shorting. And 2 pole 3 position says it all, you don;t need to add them up. If you tell someone 6 positions, you will get a switch with that many switch positions. And since it will be used in your mains AC circuit, the switch needs to be rated for 120VAC (or 240 if you are not in the USA) service at some reasonable amount of current.

ANy number of old Gibson/Epiphone amps used a rotary switch in this fashion.

[retrorod]

AND rated for at least 500VDC to handle the B+... ...Back to the Mouser catalog....Yuk!