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Mystery motor controller, anyone recognize it?

Does anybody recognize the DC motor controller in the photograph at

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?

There are a few other photos in the same directory showing detail views of a few items in the enclosure. There are no names, part numbers or any other identifying marks that I can find on the board. The only IC visible is a National 741NC, I think the date code reads February, '81. The Reliance Electric output device is a 701819-X, described as a rectifier. With six leads it might be a thyristor of some sort, but web searches haven't confirmed it.

I'm looking for information becasue I'd like to change the wiring harness to relocate the controller for better space utilization. Before I mess with it I'd like very much to know how it works, so if/when I make a mistake there's a chance of fixing it.

At the same time it would be helpful to know what it'll take to replace it, in case I can't or don't want to modify/repair it. The motor is a half horsepower shunt wound DC 1750 RPM Browning. Web searches for the various numbers on the nameplate come up mostly with firearms links, so I gather Browning is no longer in the motor business.

The application is an old South Bend lathe. Apparently somebody wanted to wind coils, so they added a soft-starting variable speed drive and a turns counter. If I kill the DC setup I can always fall back to a traditional fixed-speed motor but the present setup is very nice and I'd like to keep it working if possible.

Thanks for reading,

bob prohaska .

Reply to
bob prohaska
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It might help if you could move the wires that obscure the marks on the

6 leaded module not on the circuit board. Barring that what does it say?
Reply to
MOP CAP

Main board looks more 1970s than 80s with carbon Rs and canned opamps, if 80s perhaps JFET ones. The lower left white board is later with MO resistors. At least the opamps , easy to monitor DC levels and then try a compatible opamp in the socketted one.

Reply to
N_Cook

Sorry, it's a reliance electric 701819-X . Web searches find it for sale, but I haven't found anything like a spec sheet. It's described as a rectifier, but with six leads it's likely to be more than just that.

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contains a few more images.

Thanks for reading,

bob prohaska

Reply to
bob prohaska

It is a full bridge rectifier but two arms of the bridge use SCRs instead of diodes. Their gates are controlled (via the G1 and G2 terminals) to switch on for a variable portion of a cycle thus varying the power transferred. A Solartron variable bench power supply of that vintage used the technique to reduce the input to the linear regulator when then output voltage was dialled low and the 5 Amps would have resulted in too high a dissipation in the regulator transistors.

Reply to
Geo

Ok, now the fog is lifting, slightly 8-)

Many thanks for reading and replying!

bob prohaska

Reply to
bob prohaska

An early 70s (?) local Canadian electronics catalogue (R.A.E. Industrial Electronics) has some of these SCR/Bridge rectifiers listed on pg. 138 - made by IR. See if you can find anything on the PACE/paks design. Happy to email the two pages showing the IR versions...these devices with 6 terminals have up to six different internal configurations.

1-Single Phase hybrid bridge with common cathode connection 2-Single Phase hybrid bridge with common anode connection 3-Single Phase, all SCR, controlled bridge (8 terminals) 4-Single Phase hybrid bridge with doubler connection 5-Single Phase, all SCR, AC Switch. (anti-parallel controller) (4 or 6 terminals) 6-Single Phase, hybrid AC Switch. (anti-parallel connector) (5 terminals)

John :-#)#

Reply to
John Robertson

PACE/pak turned out to be the keyword needed. That found

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which is plausibly the modern device series. most likely the single phase hybrid bridge common cathode version.

Now, if only somebody could give a similar hint about the board..... With no numbers visible I know that's a long shot.

Fortunately, no parts are needed now, I just want to understand what I'm dealing with before redoing the external wiring.

With thanks,

bob prohaska

Reply to
bob prohaska

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