Can I use LED bulbs in my Ilford MG 500 head?

[Eric Woodbury]

What's wrong with the way it is using halogen type bulbs?

If it works, don't fix it.

I don't understand the need to use LEDs, especially white LEDs. Personally, I have built 5 LED light sources for use with 8x10. They are a pain to get them right. Diffusion without attenuation is the worst of it. And cooling. And drift. I only made mine because I've been designing LED drivers for customers (for projection and simulation) for years and decided to make one of my own. They all work fine now, but it has been a long road with many problems. I made a few for friends, but no more. Takes too much time and money.

[Larry Gebhardt]

The RH Designs controllers for that head do use full voltage and vary the duration, one lamp after the other. At least that’s how I remember it. It’s been a while since I set my Ilford head up. I will say from my experience building an LED head with 12 blue and 12 green 3 watt LEDs I have my doubts about the brightness of 2 5 watt panels further attenuated by the dichroic filters. I’m also questioning if the beam angle of those bulbs is going to be the same.

[Drew Wiley]

Loss of light output is one problem. Another is that any feedback circuit involves miniature matching specific filters also selected in relation to the specified original halogen bulb spectrum. Change that variable, and you'd need a recalibrated or independent feedback loop too, to handle the timing correctly. Plus the angle of incidence issue relative to dichroic filters themselves, which Larry just noted.

As my mother used to say, you're jumping out of the frying pan and right into the fire instead. Why?

[Thodoris Tzalavras]

So, the answer to my original question seems to be:
Yes it's safe to replace the ENH with LED… But, it probably won't work as intended…

Well, only one way to find out I guess…

Thanks to all who participated, and if/when I try this experiment I'll let you know the results.

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As a side note regarding the "why"…

I'm currently using the L1200 for contact printing larger than 4x5" negatives.
For this purpose, I can continue using the ENH even without the fan, since my exposures are short enough to pose no threat of overheating.

BUT, when enlarging (and regardless of final exposure), you need to spend some time in focus mode (to frame, and well, to focus), which (with the MG500 system) means that the lamp behind the green dichroic filter gets really hot.

So, planning ahead, I need to find a working solution to my fan not working properly.

The idea of switching to LEDs seemed to be the easiest and cheapest… if it works…

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By the way, in case this info means something to one of you, regarding the possible cause of the fan malfunction:

During all my printing sessions of the last few days, the fan operates properly for 2 minutes when I turn the power supply on, but thereafter it does nothing… the click on/off sounds emanating from the power supply are there, but the fan does not start…

[Drew Wiley]

What's the cost of an inline booster fan, pulling the air away from the head, and into an exterior duct? Maybe $75 in this country, unless you need a really quiet one. There must be ample choice in the EU too. It's far less fuss to improvise than what you're contemplating. Seems like you're thinking all this backwards. An inline duct fan can be run entirely separately from your power supply with a simple switch of its own. I've owned several big commercial Durst units requiring far more efficient cooling than the L1200, and in each case opted to run the cooling fan independently of the enlarger light power supply. More reliable that way.

[MartinP]

Small (and not so small) fans for coolling are utterly standard things for PCs and servers and are widely available. They are also cheap and, even better, reliable. Why build a new light-source and light-management system when you only need to swap a fan?

12V or 24V fans can be run from standard 'wall-wart' voltage adapters, so your replacement solution can be independent of the Ilford control system. As long as you remember to switch the replacement fans on you will be fine.

[Luis-F-S]

For the past fifteen years I've been using 120V, 250W ENH Halogen Lamps like this one:

Is it possible to replace them with 120V, 5W LED like this one:

Physical dimensions seem to match.
I'm mostly concerned about safety.

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If you need additional information regarding the specific MG500 setup I have (there were at least a couple) and/or why I'm considering the switch let me know. Hopefully the answer to my question (either positive or negative) is independent of specifics.

If the ENH bulbs work for you, I'd keep using them. You can always buy a new fan. No sense to try and re-invent the wheel. L

[Thodoris Tzalavras]

A long overdue update:

About a week after my last post, the fan died.

I kept using the enlarger without a fan for a while, constantly monitoring the head's temperature.
Since I almost exclusively use this enlarger for contact printing at the moment, exposure times are relatively short, which in turn helps keep the temp down.

At some point, I decided to try out the idea of attaching a PC fan to the outside of the head, as Randy (Tin Can) suggested.

Initially I bought 2 fans, but one of them arrived DOA, and instead of waiting for the replacement before going ahead with the test, I used a nonpermanent clamping device to secure the one good fan at hand to the vent opening at the left side of the head (left side is green, right side is blue filter), pulling air out of the head.

It's been several months now, and the head runs cooler than it did with the internal fan… actually, I can't detect _any_ warming at all now, while the front cover did get warm to the touch when the internal fan was still working…

By the way, since the initial test went so well, I never got around installing the second PC fan…

And the cherry on top, this 8cm PC fan makes almost no perceivable noise…
Compare that to the helicopter landing of the original fan…

So, thank you all for your suggestions, and for helping me find a working solution.

[esearing]

The MG 500 is a special beast with special lighting head, dual light controller, and a finicky power supply - any other type of lamp in its sockets tends to pop and die. (I learned the hard way) . If you want a different lighting system use a different head . You could sell the MG500 while it still works and put the money + more cash toward the Heiland LED system. Or you can buy a dozen bulbs for the MG500 and keep using it.

My system seems to kill the controllers. I've gone through 3 of the original ilford ones, and am on my second controller/analyzer from RH designs. Controllers are getting rare. The power supply can be serviced. The MG500 + the RH Designs analyzer gives you the ability to do split grade printing and baseline customization for different papers, plus control down to 1/12 stops. And I suppose you could do fstop calculation when changing paper sizes based on measured projected densities at the different head heights.

[Thodoris Tzalavras]

esearing,

Thankfully I never had any issues with the controllers.

The original one that came with my enlarger in 2007 was working fine when I switched to the Analyser 500 about 12 years ago.

Also, I still have 6 ENH bulbs from last time I bought a case of 10… that was more than 10 years ago…

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I began this thread, thinking that the easiest and less costly solution to the internal fan misbehaving (and soon thereafter dying), was to switch from Halogen to LED bulbs, since the only reason the fan was there in the first place was to cool down the Halogen bulbs…

Since the consensus was that LEDs would probably be safe to install but unfit for the purpose, I chose to try the next best idea…

I waited a few months before posting an update (to make sure it worked), but it looks like the external PC fan idea was in fact the best solution to this particular problem…

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Come to think of it, a better title for this thread would be "Potential solutions to Ilford MG500 internal fan failure"…

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Amendment:
I gave credit for the idea of attaching a PC fan externally and off the wall to Randy alone, when in fact it was both him and MartinP at posts #09 and #16 how suggested it… sorry Martin, and thanks to you both…