Beseler 45M Wiring

Ggtz91 · Apr 20, 2025

I recently decided to try printing at home and I found a Beseler 45M enlarger for free. It's in great shape despite its age. The one issue is that the original power cord is extremely brittle, frayed, and has exposed wire in multiple spots.

I was thinking about simply replacing the the original 2-prong cord with a new 3-prong cord. Upon opening up the motor housing and removing the original cord, I encountered my issue. I don't know which wire of the original cord is the "hot" and which is the neutral? I checked for continuity and know which wire goes with which prong but since it isn't polarized it is of no use.

Since I'm new to working on enlargers (and anything electrical), all I know is that one of the original cord wires had a spade terminal that was connected to the motor toggle switch and that the other wire was soldered to what I'm calling a "panel" where the three wires from the motor where connected as well as wires to/from the "light socket" and the toggle switch again.

I can't find a wiring diagram anywhere. Any chance someone here knows where the hot and neutral wires go before I give up on this project?

Doremus Scudder · Apr 20, 2025

If the original two-prong plug does not have a wide and a thin blade, i.e., is not polarized, then it doesn't make any difference. The original plug could be plugged in either way. That's the way the motor was designed to run. Ground to the chassis of the enlarger.

Best,

Doremus

Nicholas Lindan · Apr 20, 2025

Usually you would wire the hot wire to the switch so that when the switch is off the motor windings are neutral. But as Doremus has pointed out it doesn't matter much. And either way it would be an improvement over the original ungrounded design.

mshchem · Apr 20, 2025

Need to be cautious. 1970's and back, what looks like an "outlet" on the front of the motor housing is for a switch for the lamp.

If you get a multimeter the ground and the "neutral" will have continuity to the chassis. If this is one of the original black units, 1950's, not grounded units you need a proper 3 wire grounded cord, not hard but should have someone who knows what is going on.

mshchem · Apr 20, 2025

Ollinger's Guide to Photographic Enlargers

A short guide to and description of various photographic enlargers.

www.jollinger.com

Ggtz91 · Apr 21, 2025

Thanks to everyone for the information. With your help I was able to get everything wired up and properly grounded and its running like a dream...and a lot safer.

f/Alex · Saturday at 10:07 AM

Late reply, but oh god is the stock wiring on this enlarger absolutely insane. It's designed (At least the 45mrx I have) to use a toggle switch (or mechanical timer) to interrupt mains hot via a 2 prong outlet, the entire thing is ungrounded with the stock cord, mine had a more modern cord, but the grounding wire was just floating, the motor drive can't run unless your timer is in focus mode, etc.
Personally I bypassed the toggle switch plug on mine (I have a digital enlarger timer), but I have been thinking about maybe replacing the entire wiring box on mine at some point, just to remove the need to touch metal switches that are carrying mains voltage and all. Unfortunately I have no experience with Mains-voltage circuitry design that I'd need to do what I want.
Also, I would recommend opening up the motor box, checking the brushes, and replacing the lubricant with a modern synthetic like lithium grease. If that motor kills itself, it'll be a pain to find a replacement, and they do die.

f/Alex · Saturday at 10:23 AM

Here's an image of my wiring setup, I'm not proud of it, but I think it's slightly safer, and definitely much simpler than the stock wiring. I wouldn't let anyone who isn't me use it. Again, it's only supposed to be temporary.

Chan Tran · Saturday at 10:48 AM

It's been a long time since I had the 45M but if I am not mistaken the motor is a DC motor and the amature wires would be reversed in respect to the field wires to reverse the motor. So the polarity would change depending you move the carriage up or down.

f/Alex · Saturday at 11:43 AM

Chan Tran said:
It's been a long time since I had the 45M but if I am not mistaken the motor is a DC motor and the amature wires would be reversed in respect to the field wires to reverse the motor. So the polarity would change depending you move the carriage up or down.

90% sure motor is AC, I don't see anything to rectify the mains AC coming in. It does seem a bit old to be an AC motor, but well, there's no rectifier, and the motor runs plugged directly into mains just fine.

Chan Tran · Saturday at 2:00 PM

f/Alex said:
90% sure motor is AC, I don't see anything to rectify the mains AC coming in. It does seem a bit old to be an AC motor, but well, there's no rectifier, and the motor runs plugged directly into mains just fine.

You can run DC motor with AC power as long as you supply the field winding with AC as well. This is done also with sewing machine motor.

f/Alex · Saturday at 5:07 PM

Chan Tran said:
You can run DC motor with AC power as long as you supply the field winding with AC as well

My apologies, I'm not an engineer. Just kinda an idiot when it comes to the science behind electronics

Beseler 45M Wiring

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