Pultec EQP-1A project, replacing the current DP switch with the original

[albertors]

Hello everyone,
my first post in here after having been a lurker for long. Thanks for the (indirect) wealth of information that I was able to gather in the years, this place certainly helped a lot.

Here is the background story: I have a pair of Pultec EQP-1As whose internals I bought for cheap in the US, years ago, as a bunch electrical guts. They were said to be broken "just because of the rectifier tube" was no longer working, so with young ingenuity I thought "hey I can fix that". Turns out it was more than that and it took me months (and funds) to get them re-done. Lesson to learn: it became almost as expensive as getting a good deal on a used Pultec in working condition..

Now I have a beautiful pair that uses the old transformers and was re-done to work and get matched at the best possible. In re-doing the circuitry, the current switch is no longer original. It's a dual pole single throw that goes more or less as some DIY builds around plan. I attached a picture of the schematics.

Now, I know I can't replace that with the original Pultec switch..but I could if I use a relay.

So my idea would be to get a relay, take the 24V from the lamp or the 12V from a tube heater and use the Pultec switch to turn the relay on and off. The relay will the do the dual pole work as the current switch is doing now.

I attached some pictures to make it easy to see.


- A picture of the actual switch (not mine but pretty identical)



- Schematics of what happens during on/off with the current switch



- Picture of the original Pultec switch I'd like to install



- Picture of a relay that * I think * would work for this purpose



Can anyone help me out and confirm this is doable? Thanks!

 

[Cardinen]

Hello Albertors,

yes you can do it with the relay, but what's wrong with the dual pole red switch ?? only for the aesthetics ??

happy DIY! 

 

[albertors]

Hello Albertors,

yes you can do it with the relay, but what's wrong with the dual pole red switch ?? only for the aesthetics ??

happy DIY! 

Nothing is wrong, only aesthetics. The hole in the faceplate is bigger (original) and the switch is smaller, so it kinda wobbles when moved up and down. It won't break contacts and it stays shielded so it's not even making noises, but I have the old originals here and it's a shame not to see them

So 24V from the lamp would be doable? Will it dim the lamp when on?
I know without ratings it's hard to say but..getting 24V from the lamp rails would be much faster to do.

Also, nothing beats the face of people when they use the bypass free floating position and you go: "oh no, you broke the switch".

 

[radardoug]

Have you looked for a double pole switch with that actuator?

 

[albertors]

Have you looked for a double pole switch with that actuator?

Mh, no! I assumed that type of actuator (and the whole switch) belong to the past and nothing like that exists. But I might be wrong, does it exist?

 

[PRR]

It *looks* like, if you had two of those switches, you could take the pole off one, stack it on the other, and have a DPST switch.

This type switch construction was designed so you could order one to a dozen poles. 6P switches were fairly common then.

You may need a bit of insulation where the first pole pushes the second pole.

Screw-length may be marginal but you can get longer screws.

It also looks like some guitar switches, tho I am not familiar with those pole-counts, bushing size, or level lengths.

 

[albertors]

Thanks PRR! I see what you mean. Between the two solutions it seems faster to do the relay thing (I only have two switches for the moment, and the relays are cheap) but the stacking poles idea is cool, I didn't know about it!

 

[radardoug]

This one says its 2 pole 2 position.
https://www.don-audio.com/pultec-bypass-switch

 

[albertors]

This one says its 2 pole 2 position.
https://www.don-audio.com/pultec-bypass-switch

Well, it looks to me as if it's not. At least in mine you have 4 pins, from top to bottom:
- Pin 1 ..the top one is never connected to anyone, but does grounding
- Pin 2 is connected to 3 only in the "off position"
- Pin 3 is connected to 3 or 4
- Pin 4 is connected to 3 in the "on position"

So if you need to switch two poles in a single throw, it won't happen..looks to me as if it's a simple single pole?