Using a modern power supply with an old enlarger (Durst 1200, DIY)

Not sure if what I've done is interesting enough to show here, but someone may find it useful.

I have a Durst AC1200 with a bum power supply, and even when it was working I spent more time troubleshooting 30 year old circuitboards than I did printing.

I was able to find a good deal on a VLS501 head with no power supply, so I figured I could use a modern "Switching" power supply instead.

http://i.imgur.com/8D7Zii0.jpg

The Durst EST500 outputs 23.5 VDC at 275 Volt-Amps (11.7A). I figured that any modern "Switching" power supply of similar capacity would work. A hopeful sales guy from work dropped off a 24 VDC 10A power supply as a "freebie", so I figured I'd give it a shot. Seen below is a PULS CP10.241-S1 Power Supply and my Open Source F-Stop Timer (link).

http://i.imgur.com/9SCEggt.jpg

Here is a diagram of how I connected the power supply to the enlarger:

http://i.imgur.com/MRXYw5f.jpg

http://i.imgur.com/XuSV7vy.jpg?1

And so far, I'm getting very consistent bulb warm-up times, extremely consistent prints, and best of all, I'm not dependant on a 30 year old Italian power supply.

Let me know if you have any questions.

Note: This is a very expensive industrial power supply meant for high-reliability environments. Virtually any inexpensive DIN-rail mount power supply with sufficient specs from Mouser or Digikey would function equally as well. I've seen similar power supplies go for ~$25 on eBay.

Disclaimer: Not an electrician, so mess with electricity at your own risk. There is enough power here to kill you, so be careful out there.

Thanks for posting, sure is very useful for future reference, there quite a few of these machines out there !

Best,

Cor

My favorite trick is to install bulbs that run either straight 115v or straight 240v, then throw away the stupid power supply! Works every time if your in-house voltage reads consistent and you isolate any odd circuits, which are generally 115 anyway.

Very simple and basic thing to check out on any "rewired" enlarger. The plug has 2 prongs. The wide one is the neutral and attached to the female screw part of the bulb's socket. The narrow one is hot and attached to the center piece of metal in the bottom/back of the bulb's socket. If the connections are reversed, the outside of your enlarger may be hot and in the environment of a darkroom a VERY, VERY dangerous thing.

When eliminating the low voltage power supply recall some 120/115V MR 16 lamps fit a GY5.3 socket (flat pins). Whereas the common low-voltage MR 16 lamps can have the round pins with GU 5.3 base. New socket is a good idea for any enlarger refurbish project anyway.

One concern is that many SMPS P/S's have a turn on delay, and sometimes a ramp up voltage, so for short exposure times with a timer, this might affect exposure...

Steve K

For anybody else with the same problem, All Electronics (www.allelectronics) has a similar power supply-24VDC-10 amp. Catalog # is PS-2401 and price is $37.50. Hope this helps!

Quote:

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Originally Posted by LabRat

One concern is that many SMPS P/S's have a turn on delay, and sometimes a ramp up voltage, so for short exposure times with a timer, this might affect exposure...

Steve K

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Steve, that was a problem when I was running my relay on the wall power side of the power supply. I had inconsistent ramp-up times, sometimes 1.5-2 seconds. By moving my relay to the 24V side, the power supply is "on" during the entire darkroom session, so it has a turn on delay in the milliseconds once the circuit is closed.

I have an AC1200 with a failed controller. I sent it for repair but it came back as uneconomical to repair.

fj55mike - If you need me to measure voltages etc, let me know and i'll dig out the PSU. Obviously i'm on 240vac in the UK and the readings would be unloaded.

I ended up going for an MG500 head and controller instead.