Durst enlarger lamp conversion

[Stubob]

Hi there, I'm having problems with the lighting on a Durst 370 colour.
It is a 12V/100W dichoric lamp fed from a 240/12V transformer.

Now, I already have Durst 370 B+W which is fed 240V from an exposure timer, and my cunning plan is to replace the colour head's lamp for a 240V unit so I may do away with the transformer and use the timer.

The only drawback I can see with this would possibly be the temperature of the 240v/100w lamp, would it be any hotter than the 12v version.

Has anyone tried such a conversion? And if so had any success? I'm keen to hear.

 

[OzJohn]

100 watts is a 100 watts so the heat should be the same but I still wouldn't do this for 3 reasons:

1. It is unlikely that the two lamps will be physically compatible so you may have to make mods to lamphouse/lampholder - see #3
2. I don't think a 240V/100W halogen lamp will have been designed for enlarger use and may fail early due to frequent switching. In colour printing you don't want to change lamps any more frequently than necessary
3. It is potentially dangerous! 240V is lethal and you will be introducing that potential into a device designed for 12v, possibly only lightly insulated and probably not earthed (although all enlargers should be)

In theory, the safest way to do what you propose would be to use the 240v output from the timer to drive the 12v100W transformer but I doubt that the timer output could handle the 8-9 amp current draw of the 12v lamp. Might be wisest to buy another timer and keep the 12v100w lamp. OzJohn

 

[polyglot]

Heat is the same but it's dangerous because the enlarger head insulation is not mains-rated and probably not earthed; it depends on the transformer isolation for safety.

Secondly, the transformer is probably ferroresonant and therefore providing some regulation that reduces brightness variation with mains voltage.

Seriously bad idea, sorry.

 

[ic-racer]

Most condenser enlargers have that 'lethal' voltage running the lamp so that is not a concern (as you know from your 370 B&W) "Cold Lights" of course, can run at voltages much higher than 240V. You will need to put a new socket in place (pins on the high voltage lamps are slightly different) and at that time you can re-wire it with the appropriate voltage wiring and connectors.

You might find some useful info here: (there was a url link here which no longer exists)

 

[OzJohn]

Most condenser enlargers have that 'lethal' voltage running the lamp so that is not a concern (as you know from your 370 B&W) "Cold Lights" of course, can run at voltages much higher than 240V. You will need to put a new socket in place (pins on the high voltage lamps are slightly different) and at that time you can re-wire it with the appropriate voltage wiring and connectors.

You might find some useful info here: (there was a url link here which no longer exists)

Sorry but I think your advice to a person new to this forum and of unknown experience is irresponsible. A darkroom is not the place for dodgy, jury-rigged electrical gear no matter what voltage it runs on. OzJohn

 

[ic-racer]

Sorry but I think your advice to a person new to this forum and of unknown experience is irresponsible. A darkroom is not the place for dodgy, jury-rigged electrical gear no matter what voltage it runs on. OzJohn

The instructions given are not directed at the incompetent. In fact they are not directed at any specific person. "You" in my post is, of course "you" the reader.

 

[Steve Smith]

I'm having problems with the lighting on a Durst 370 colour.

It would help if we knew what the actual problem was. You can my transformers for domestic 12 volt dichroic lighting so if it's a transformer problem, the easiest solution is to get one of those and keep the 12 volt bulb in the enlarger.

I would also probably do what ic-racer suggests but that doesn't necessarily mean I would suggest someone else does it. It doesn't need to be dodgy or jury-rigged. It can be done properly. Even when something does look decidedly home made, it can still be perfectly safe.


Steve.