Replacing enlarger power supply

[treddy]

I got at the capacitor (which I deliberately left off overnight and also discharged just in case). No signs of charring either there or on any of the wires. Without actually charging it up and testing it, I'd say it looks fine. My (limited) familiarity with electronics is all in computer circuits and low voltages, not with high voltages and power supplies. For that reason, I think I'm not going to go any further in testing the components.

Chan, thanks for the bit about the voltage regulation coming from the battery -- I hadn't thought that through all the way.

Tkamiya -- if you come up with anything that might work, I'd be happy to hear. Might cruise some craigslist too and see if I cant find something that might suffice.

Tim

[treddy]

I was thinking about this route too -- just switching out the light source whole-sale with something more modern. Sunk cost of the bulb I just bought would be annoying, but a big deal. Thanks for the links. I'll check them out.

Tim

[mr rusty]

Thanks for the links. I'll check them out.

I didn't do too much research for them....... There are probably many alternatives out there. Still don't know where you are UK or US??

[treddy]

I'm in the US (Filling out profile now...)

Philips makes a 75W 12V bulb with the same base. That might be a nice solution.

Most bulbs seem to be "multi-reflective," having what looks like a faceted inner surface. It seems to me that would be a huge problem with printing, but maybe I'm wrong. Anyone know if by the time the light gets down to the negative it won't matter?

Tim

[mr rusty]

On the V1 with its "light pipe" I doubt it will make any difference if the bulb refelector is faceted or not. The end of the "pipe" is diffuse.

Have you got the manual? It tells you how to take the condenser apart to clean it. I think it may be online somewhere, but if not say, and I'll scan mine.

[treddy]

Thanks for the offer. I got the manual from Ollinger's Guide to Enlargers.

[polyglot]

Please don't set about modifying mains-powered electronics unless you know exactly what you're doing, which clearly is not the case here. A darkroom fire and/or electrocution is not worth it.

If it's a 19V bulb, the cheapest and safest option is to use a laptop power supply of sufficient power rating. It will even have better regulation than the old magnetic supply!

If it's a 24V bulb, you can buy 24V switching power supplies off eBay for peanuts, well under $100 for 300W+.

The faceted reflectors on some bulbs will be irrelevant for an enlarger; they're just a slightly different approximation of the parabola behind the filament. If you're replacing the bulb with a new/different kind, what matters with a condenser enlarger is that you get the filament in the exact same spot or the condensers won't be focused right and you will get uneven lighting of your negative. If you're building a replacement bulb mount, include some fine sliding adjustments to get it all aligned. Don't put a higher-powered bulb in the enlarger unless you upgrade its cooling.

[ic-racer]

Looks pretty nasty inside. I'm guessing the orange/yellow coating all over the inside (some sort of fluid leaked out all over the place?).


Attachment 64244

Is the big thing in the middle the capacitor in question, or is that the transformer?

I found a laptop power supply listed at best buy that is 19V, 100W for something like $30. Might be an easier way to go, I'm thinking? If the output is controlled enough to not fry a computer, I imagine it would be ok for enlarging too?

Tim

Is that dry? It does not look different from the usual lacquer that most transformers are dipped in. I don't see a regulated supply, just a transformer. Is there any more to it. Can you check the resistance on the primary and secondaries of the transformer. This sparked and smoked? Is there a fuse?
What do the two white wires go to? What is the structure the red and yellow wires go to?

[ic-racer]

Here is a replacement transformer but it only has one set of secondaries.
http://www.alliedelec.com/search/pro...x?SKU=70181275

[DWThomas]

Actually, the transformer visible in that picture of the internals looks like a ferro-resonant constant voltage transformer. Note that there appears to be core between the two winding sections. This was pretty typical for CV stuff - Sola is one brand name I remember. I'm not sure what the gizmos on the plate on the left are but looking again, they are probably terminals of a capacitor clamped down and sticking out the underside of that plate/chassis.

What is under that plate presumably holds the key. There are indeed usually capacitors in ferro-resonant supplies and caps do not age gracefully.

(Of course, it could be good now that you've let the smoke out. )