Pathetic question about Superior Electric Powerstat terminal boards

[D.Doerschuk]

Hello Everyone,

This is my first post, and I'm afraid my question is pathetic. Here goes: I'm rebuilding the carriage drive to an old lathe, and the manual controller uses a Superior Electric Powerstat Type 21 (specifically, 21-1004). The field wiring comes into 5 screw terminals and attaches normally to the front of the bakelite terminal board. The factory connections to the coil and wiper are made to ~~24 AWG solid wire connectors at the rear of the 5 screw terminals. The embarrassing part of my question is that while cleaning up the Powerstat I broke off one of the factory wires at the connector. The pathetic part of my question is that I cannot see how to re-open the rear-of-terminal connector to install a spankin' new wire. I have pushed, turned, pulled, removed the front terminal screw and looked inside, and danced the Dance of Humiliation. Shown below is a photograph of the back of the bakelite terminal board.

I did say this was pathetic.

Please help.

Thank you!
Dave

 

[Visitor]

Have you tried loosening the screw in the front? It looks like the screw may pull in the back piece to clamp the cable.

 

[D.Doerschuk]

Thank you, Visitor! Regrettably, your idea didn't do it. I also tried unscrewing the terminal screw part way, and then putting pressure on the screw to try and pop the back clamp piece open. No dice. If it really can't be opened, I suppose I could solder on a slightly longer wire and ring-terminal it to the front of the terminal board, but that would be kind of bush league.
Dave

 

[JimB]

I cannot remember if I have ever seen connections like these before in 50+ years of experience.

However, if I was confronted with the problem as you describe it, I would simply solder a wire to the back side of the terminal.
My best guess is that the terminal is made from brass and plated with some material (Tin? Nickel?), so I would clean the plating from a large enough area to make a solder joint and solder the broken wire back on.

It will probably need a fairly large soldering iron to heat up the chunk of brass in the terminal.

JimB

 

[Les Jones]

A small variation on Jim's suggestion extend the broken wire by soldering another piece of wire to it. Then drill a small hole through the panel and pass the wire through the hole and pass it round the external screw of the terminal under the external crimp tag. (Or put a solder or crimp lug on the end of the wire.)

Les.

 

[dr pepper]

Looks as though theres a tube in a tube, the inner one having a hole in for the wire to go through, tightening the screw pulls the 2 together and pinches the wire.
Undo the screw and see what happens.

 

[shortbus=]

Kind of looks like the lug that holds the wire is slotted. Like a round nut that screws down to pinch the wire to the lug. Like this one -

 

[D.Doerschuk]

Thank you all very much for your thoughtful contributions to solving my problem! I suspect that several of you are on the right track, but the clamping mechanism is either a one-shot deal or it has self-welded over the course of its very long lifetime.

JimB's suggestion was the one I finally took. The terminals were, as he suspected, plated brass, so a swipe or two of a file and a large wedge-tip on the soldering iron ended up making a reasonably respectable connection.

So again, I thank you all!

My next problem is sourcing an IP67-rated Fahnestock clip. Any thoughts?

Best regards,
Dave