Transformer question

[yellowcat]

I need to get a new transformer for a Durst M605 enlarger that a friend wishes me to fix, the old transformer is a laminated core type.

Looking at possible replacements I see that as well as laminated core there are toroidal transformers and an electronic low voltage lighting transformer.

Are these all interchangeable or is there anything else I need to consider?
The spec for the transformer is 12V 100VA running on standard UK voltage.

 

[Bob F.]

Try the 105VA version of this: Dead Link Removed The voltage and current rating are compatible.

 

[ic-racer]

Are you replacing a fried transformer in the Coltra TRA 305N unit? If so, I'd get one similar to the original.

If you have a Coltra that just does not work, perhaps the transformer in it is still good. If it has 24V secondaries, you can bypass all the voltage regulation stuff and just rig up a half-wave rectifier circuit with a rectifier diode. That will give you about 12V AC unregulated to drive the head. I 'repaired' my Minolta 12V supply this way in 1978 and it is still working fine. The advantage to this method is that you can keep the original power supply box and connectors & cables.

If you are just looking for a whole new power supply, I think that an aftermarket 12v 10A supply would probably work (that would be good for up to 100W bulb).

I agree something similar to the one BobF posted will probably work but make sure you get the 100W one.

 

[RH Designs]

Try the 105VA version of this: Dead Link Removed The voltage and current rating are compatible.

I've been using one of these on my LPL7700 for years without trouble. Remember it's a stabilised output too which is a bonus.

 

[yellowcat]

Many thanks, I will visit my local Maplin at the weekend.

 

[Bob F.]

Note that the 60VA and 105VA units are different shapes and colours - the 105VA one that you need is the black one. On my screen the picture of the white 60VA one comes up by default - roll the mouse over the small thumbnail images and the other one will display.

Dead Link Removed

Of course, life being what it is, when you get there they will both be different to the images in the catalogue...

 

[RH Designs]

Of course, life being what it is, when you get there they will both be different to the images in the catalogue...

Yep, mine looks like the one in the catalogue, but I didn't get it at Maplin! The important thing is the rating not the shape; 105VA seems to be a standard among LV lighting transformers but so long as it's more than 100VA you should be OK.