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Electrcity Help! Enlarger bulb keeps blowing out!

Rosie A. , Dec 28, 2006; 07:53 p.m.

hello, i believe i have quite a crazy story... here it goes..

I have a darkroom in my bathroom. I inherited an enlarger from my grandather... an Omega C700 color dichroic. I used this enlarger off and on (not often) for a few months. In preparation for a small show i began to use it much more often. The bulb Blew out (no big deal it was old) so i got a new one. used that one for a week, then it blew out.. (now that seems funny, it said 40hrs worth of use)... i bought another bulb and it blew out the first time i turned on the enlarger. so i talked with a few people at my local camera/photo shop. (very experienced and knowledgeable people) we thought that the enlarger socket was probably bad and causing the short... Since i had this show coming up, i couldnt wait the few months it would take to send it into Omega so i bought another enlarger. This time an Omega C760. It worked Great... for a week and a half or so but then (just when i was done printing what i needed thankfully) it blew out again. Now this whole time i had had a voltage stabilizer between the the timer (Gralab) and the enlarger, but no surge protector on the wall outlet. So I bought a surge protector before i tried to use it again. when i did (about 3 weeks later) I tested the enlarger for about 10-20 seconds and it worked fine. when i switched it back on to focus it blew again. wahts going on????????

So---- I find it hard to believe that BOTH enlargers would have bad sockets. and would have believed that it was b/c i didnt have a surge protector, but on the last try, i WAS using one!

Is it possible for the electricity to be so wonked out that it surges even through the surge protector and the voltage stabilizer?

Could it be my timer? (most people seem to think that unlikely)

Could it have something to do with the humidity level since it is used as a bathroom as well as a darkroom? (though i dont print directly after showering)

NOne of the other appliances or light bulbs in my house, or the radio or safelights in the darkroom (different outlet)have done anything even remotely crazy like this.

I have read a few other threads about electric problems- receptacle isnt grounded correctly,the polarity is out of whack..... i will get a plug-in checker to check these, but does anyone have any other thoughts? i don't know much about electricity so i am learning as i go...

also, i read on a thread that color enlargers must "have forced-air cooling fans in addition to the heat-absorbing glass". I am 99% sure mine does not.(i certainly dont see or hear one!) could this be the problem? would the heat blow it out as soon as i turn it on?

Please help! I want to get back in the darkroom... but 30 bucks a pop for the bulbs is ridiculous.... I'd like to have an informed hypothesis before i go trying stuff!

THank you!


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Michael Axel , Dec 28, 2006; 08:06 p.m.

I have a Chromega BXL (about 20 years old), and have never had to replace the bulb. As for cooling fans, they don't need them because of a heat sink built into them. You didn't say exactly "when" it blows. When the timer comes on?

I'd put the surge protection before the timer, and not in between. It could be a short in the enlarger or timer, I suppose. How many bulbs have you gone through? Maybe you just got a bad replacement bulb.

Andrew Limiti , Dec 28, 2006; 08:45 p.m.

I suggest you find a knowledgeable friend that knows how to use a receptacle tester to ensure the hot leg is correctly wired, the neutral is connected, and the safety ground is okay. Reversed wiring, a bad neutral, or no safety ground could result in voltage spikes when the unit is switched on resulting in a blown bulb. These low level surges may be enough to fail the bulb and connecting a surge protector won't help if the outlet is wired incorrectly.

I would also expect that the head would have forced cooling, though I can't confirm that as I have the Beseler head. Mine has a fan that comes on when the head is powered up. Do you keep the enlarger in the bathroom all the time? If so the humidity could result in condensation on the bulb, resulting in a short life span. I would check the obvious first, you may find that the outlet is wired wrong.

BTW, you can get cheaper bulbs on line, probably 1/2 the price of buying it locally. I bought locally once, over paid big time, and ordered the bulb and spares online for a fraction of the local cost. Try: www.replacementlightbulbs.com as a start.

Conrad Hoffman , Dec 28, 2006; 10:11 p.m.

It's hard to blow a bulb because of bad sockets, arcing, or even *normal* surges- unless the problem is so bad it overheats and destroys the bottom of the bulb! My guess is you have a bad voltage stabilizer, and it's either doing something really bad on startup, or provides too high a voltage in general. Bulb life goes down by some rather large factor for increased operating voltage. Get somebody who knows what they're doing to measure the voltage at the socket under load.

Andrew Limiti , Dec 29, 2006; 02:38 p.m.

Didn't realize the voltage stabilizer was not part of the enlarger. If you can take it out of the equation, that could prove whether the stabilizer is good or not. I still recommend checking the outlet wiring for two reasons, it may be wired wrong, or the grounding may not exist which can result in a shock or worse when working in a damp environment such as a bathroom. Bad wiring, specifically lack of a neutral can result in overvoltages that can blow bulbs, it happens quite frequently. I'm not sure what the stabilizer's role is here, but I assume it attempts to maintain constant voltage so that the lamp output is constant (a guess. Testing a lamp under load could be difficult to do unless you know someone very comfortable working around electrical components.

Gene E. McCluney , Dec 30, 2006; 11:44 a.m.

I had the same problem with a larger 4x5 Chromega enlarger that had a separate Omega voltage stabilizer. Turned out to be the voltage stabilizer, and so I just stopped using the voltage stabilizer, and my bulb problems went away. Modern color papers are far less sensitive to minor bulb fluctuations in color temperature, and VC papers don't care much either about the very minor bulb fluctuations due to voltage variance. And...in general, our electricity is more stable voltage than it was 30 years ago.

If your voltage consistently runs above 120volts (USA) or 240volts (Europe, elsewhere), then you have an issue with your electric service provider, and they must correct it.

McCluney Photo

Jim Appleyard , Dec 30, 2006; 12:03 p.m.

I have a C760 with the same problem and at $16.00 a bulb it get expensive and frustrating. I was never able to figure out just what was causing the problem. I did send the head back to Omega and they soldered in a couple of new gizmos (don't know exactly what they were), but the problem still exists.

Omega makes a fine enlarger capable of doing nice prints, but IMO, there's not way to get rid of all the heat that builds up, even with colling fins.

The Omega now sits in a corner and I'm using a Beseler 4x5 with a built-in fan. Haven't blown a bulb yet, which leads me to believe that power surges are not the problem with the C760.

This may not be of much help, but at least you know someone else has the same problem.

Andrew Limiti , Dec 30, 2006; 03:47 p.m.

If heat turns out to be the problem, a muffin fan from Radio Shack could solve that pretty easy.

Jim Appleyard , Dec 30, 2006; 07:10 p.m.

I tried a small electric fan, blowing on the enlarger head from about 12" away. It gave me about an extra day of bulb life.

I'm not familiar with the Radio Shack model.

Andrew Limiti , Dec 31, 2006; 08:11 a.m.

Muffin fans are used for electronics where heat sinks can't dissipate the heat fast enough. See here:

Radio Shack Model: 3" AC Fan | Catalog #: 273-242

Avoid hot spots by spot cooling with this powerful 120VAC 3 cooling fan.

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