Durst Lab 1200, CLS450, TRA 450 power supply

I've posted this question on another forum, with lots of views but no answers, so I hope folks don't mind if I post it here too.

I've acquired a Durst Laborator 1200 enlarger with CLS 450 head. I also have the TRA 450 transformer/power supply, but not the ST450 Stabilizer/Timer unit.

I've found a brief discussion of this setup here: http://www.apug.org/forums/archive/i...p/t-40367.html.

My question is whether I can use a conventional (eg Novex) timer to drive the TRA 450. The TRA 450 has a timer power outlet on the back which supplies 220/240 volts (correct for us here in Australia) for the timer, but I'm wondering about the correct input voltage from the timer to the TRA 450. I would hope that the ST450 Timer unit would output at normal mains voltage, but would like to check. The timer input socket on the TRA 450 has a conventional pin pattern but has a moulded bar in the socket to prevent insertion of a standard plug.

Short version: for the Durst TRA 450 (Australian version) what is the correct voltage for the input from the timer?

Alternately: what is the output voltage of the ST450 (Australian version)?

Thanks.

Chris

I have always run the TRA450 after a standard timer - mine is a old electromechanical Klimsch timer for process cameras. You will run into problems with many electronically switched timers, though - very few can handle that 250W transformed load.

I don't know whether the timer outputs low or high relay voltage (or rather, whether the timer input accepts high voltage) - if the latter, you could hook up any third party timer though the timer loop on the transformer as well.

It may be similar to the Durst EST2000 and EST1000N units. These power supplies for the CLS1840 and CLS2000 heads have a timer input circuit that is optically isolated from the rest of the circuit. It is like an optical relay and it can be triggered by any voltage from like 80v to 220v without damage. In other words, none of the current to the CLS bulb comes through the timer input. It is just a trigger.

I have had mine hooked up to a regular timer and it worked fine. Your smaller CLS transformers may be similar.

This part of a schematic is NOT your unit, but yours MAY be similar.

Thanks Sevo and ic-racer. That helps. I also found some nice pics of this unit and the timer at the bottom of this page.

On closer inspection, the socket for the timer input is an identical design to the socket for the mains input, so logically it should accept mains input. The moulded bar in the socket is apparently an early form of this connection (I think it's called an IEC connector - similar to those on the back of computers). One of my sockets is cracked, so I'll replace them both with new ones without the moulded bar.

I have high expectations that I'll be able to get this TRA 450 unit working ok. But just for interest, would a unit such as this one listed on ebay be able to power the CLS450 head? 24 volt, 350 watt, switch-mode power supply. My enlarger has a 24v 250w bulb. I'm no electrical engineer (obviously!) but to a layman this looks like it might work.

Thanks!

I never had the Durst timer/stabilizer for my CLS450 TRA450 combination I have always used a simple Philips PDC011/04 timer which is rated at 250w no problems.
Good luck.

Thanks Tony. I took the plunge and tried it, and it seems to work fine for the few short test runs, using my little Novex timer. As IC has pointed out, the timer just triggers a big relay that actually carries the big current so there's very little load on the timer. The CLS head is quite interesting, as it needs 24 volts for the bulb, plus mains voltage (240 volts here) for the fan and the panel lighting.

Now my only problem is that the enlarger is too big and heavy for me to set up in my temporary darkroom (ie the bathroom)! Roll on Christmas holidays, when I'll have time to start building! :)

Enjoy Chris, I love building and modifying darkrooms and adapting and modifying various things for darkroom use.
Good luck.