Lots of enlarger bulbs blowing....why?

[Tom Stanworth]

Hi,

I started using my used devere 10x8 recently when two bulbs blew. There was a little flash ( which I could see from the small amount of light spilling from around the carrier onto the wall) and the two right side LEDs went out, showing that those two bulbs had gone. I inspected them and they had blown. I replaced them and within a few prints the left two bulbs went. This time there was no flash, the light source just dimmed and the LEDs went out. I have replaceed these two so there are now 4 new bulbs in the head.

Being used to smaller enlargers with less bulbs and having only one bulb go in 3 years, can you help on the following:

I once heard that all bulbs should be replaced when one fails. Is this true and if so, why?

Could it be that there was some form of surge which blew a bulb in a sudden way (flash) taking another with it immediately due to an increase in load and damaging the other two, which then shortly after gave up the ghost? (I hope so)

Could there be a more serious problem? (I hope not)

I have made a few prints and all seems well for now, but heck, the bulbs cost a fortune and if I have a bulb eating enlarger it could hurt a lot.

Thanks

Tom

 

[Nick Zentena]

Bulbs have a certain life. If you change them all at the same time then it's reasonable to expect them to die more or less at the same time. Obviously it won't be 100% exactly the same time but within a window.

The other issue is bulbs age and change colour. If you're printing colour then having a mix of old/new bulbs might cause problems.

I'm guessing this is a new to you enlarger? The bulbs could have gotten jostled in the move. They may just be old. When I got my smaller Durst the bulbs died not long after it got home. The replacement bulbs have lasted since then.

 

[Bob F.]

Not familiar with that enlarger, but if it has a voltage regulator of some description, you may want to check the voltage at the lamp sockets to make sure it is not feeding them excess voltage.

If they are halogen (you probably know this already but it's worth repeating for anyone that doesn't) do not touch the lamps with your bare fingers: the oil from your skin will cause hot-spots that will cause the lamps to fail prematurely.

Thinking about it, it is possible each pair of lamps are wired in series, in which case only one of a pair may have actually died and that one of each pair is still OK.

My best guess is that Nick has hit the nail on the head and you will have a couple of years wait for another surprise...

Cheers, Bob.

 

[Tom Stanworth]

Two bulbs were of one brand and two of another, so they probably were not of the same age, but may have taken a few knocks I suppose. They blew in their respective pairs. It is stabalised and I will definitely check the voltage. One bloke I spoke to said that if oldish bulbs have sat idle for a while (this head has been in storage for 18 plus months) they tend to blow soon after being used again. May not be true, but worth a thought (cant see the mechanism tho)

I printy mono only so no real colour balance issues.

Thanks
Tom

 

[Bob Carnie]

hi Tom

I have run into this problem before , operated a lisle camera with I believe 16 bulbs, they seemed to blow in pairs and around the same time, once you replace with new they will last for a long time , you may unfortunately need to replace all and continue with new.

 

[Bob Carnie]

Tom

sorry , didn't mention this, when replacing bulbs make sure you wear cotton gloves. the oil from your fingers is not good for longevity on these types of bulbs.

 

[noseoil]

If there is a chance that the bulbs may have been touched by someone, they should be cleaned. A cotton ball with denatured alcohol will remove any residue of noseoil from the surfaces. We had a customer who learned this the hard way on his work lamps. He complained bitterly about the cost and reliability of replacement bulbs until someone asked him if he had touched the bulbs or read the included instructions.

 

[Tom Hoskinson]

A couple more thoughts about light bulb failures.

In general, heat will reduce bulb reliability and a multi-bulb head will tend to run hotter than a single bulb head. Check to make sure you have good air circulation around the head and make sure any cooling vents are not obstructed.

Voltage spikes can cause catastrophic light bulb filament failure. High voltage (that exceeds the bulb's voltage rating) is also an enemy of filament reliability. Your line voltage may be too high and "dirty" as well. You can ask the electric power company to put a voltage monitor on the electrical service to your house.

 

[Tom Stanworth]

About touching the bulbs, I always assumed that this applied to the bulb itself rather than the reflector cone (which I touched) I took care not to touch the glass bubble around teh filament of course. Should one avoid touching the relector?

Tom

 

[Bob F.]

About touching the bulbs, I always assumed that this applied to the bulb itself rather than the reflector cone (which I touched) I took care not to touch the glass bubble around teh filament of course. Should one avoid touching the relector?

Tom

Good point....


I would assume that as long as it is not a sealed unit (where the reflector is part of the lamp itself as opposed to something that simply surrounds the actual lamp) touching the refector would be OK. Having said that, I would be inclined not to risk it as it is going to get very hot too.

Bob.

 

[Claire Senft]

Increasing bulb life

It is my understanding that if you are able to reduce the voltage by even ten percent that the bulb life is greatly extended. I use a condenser enlarger and I use a constant aperture and time. I control my exposure time thru adjusting the bilbs brightness. To control the voltage I bought a lamp dimmer from Home Depot...approx. $10.00 It works very nicely. I also use one on a bulb for viewing wet prints so that the brightness of my print examination is similar to the conditions in which they will be displayed.

 

[Woolliscroft]

Thinking about it, it is possible each pair of lamps are wired in series, in which case only one of a pair may have actually died and that one of each pair is still OK.
Cheers, Bob.

That one is well worth checking. It would be unusual for two bulbs to go at the same time, let alone for the same thing to happen twice. The chances are that two of your old bulbs will still work, unless there is a fairly serious electrical problem that is putting in fairly massive spikes. I don't know the enlarger so don't know how it is wired.

David.

 

[BarryWilkinson]

If you know someone with an electronics background they could check/adjust the output voltage of the power supply using a 500W load. There are cheaper 24V 250W lamps around than the type used by De Vere. Simpy wire two test lamps in series to make a test load. Mount them where the heat will not cause any injury/damage.

I believe that the De Vere power supplies 'bleed' a little current to keep the bulbs warm to reduce the start-up stress? I have a single bulb De Vere head, with the lamp on measuring the lamp voltage shows 22V, Lamp off 1.45V. There are at least two types of De Vere power supplies, Linear and switchmode. Mine is a switchmode which appears to have the 'bleed' facility. Not sure if this is applicable to the Linear supplies?

Another possible cause is the ceramic lamp holders are burnt. They do arc when old and cause additional heat to the lamp.

Barry

 

[BarryWilkinson]

I just reailised that your head is a 8x10, requiring 4 test bulbs. Not sure if these are in series or series/parallel.

Sorry for the mistake

Barry

 

[Tom Stanworth]

two bulbs blew both times. The filaments on both had gone. I now have spent a whole day printing on the new bulbs and all seems well, touch wood.

 

[Randolph Bracey]

Had a similar problem years ago. It was amazingly simple to correct, and cost NOTHING!

I had a Beseler 67S dichro head that used the original quartz-halogen bulb for years until it died. Paid $25 for a new one that lasted only a few hours. Went back to shop to complain. They graciously replaced it gratis and then told my why BOTH had failed! Not a bad lamp, not a voltage spike (already reduced from 120 to 24V), but bad AC plug prong.

This was years ago before polarized plugs and before three prong, grounded plugs. We dinosaurs remember the old plugs had only two identical prongs. Each was made of bent copper, slightly separated from itself so that it expanded to meet the metal in the receptacle. Over time, the bend becomes flattened and acts like a single blade. When plugged into the receptacle it makes initial contact, but occasionally the contact is momentarily broken, then immediately restored. This happens repeatedly, sometimes very quickly causing arcing in the receptacle, which you cannot see or hear. Naturally, this is detrimental to the bulb and soon burns out the filament. The solution then was to separate the bent metal of each prong of the plug, and keep them separated. This I did and the problem never occurred again. Bulbs lasted for years. The salesman at the photo store was 100% correct.

I, too, have a DeVere, and it has solid plug prongs. If your plug prongs are folded copper that have been flattened, separate them with a small screwdriver. But since almost all electrical equipment today has either polarized plugs or three-pronged plugs, I doubt that is your problem. However, the wiring to your receptacle or the wiring from the plug could be intermittently defective. If you are getting unperceivable, split second interruptions of current to the lamp, you are shortening the life of the filament. Two things could be wrong. First, check for tightly fitting plugs, bad wiring in the receptacle, or bad wiring to or from receptacle. Frayed or cracked insulation could indicate old or damaged wiring and could be suspect. Inadequately spliced or poorly wirenut-joined wires also are suspect.

Second, and this is a long shot, check the ground. If non-existent or insufficient in the receptacle, fix it AND run a redundant ground wire from the enlarger chassis to a nearby metal plumbing pipe, bypassing the receptacle ground.

Barring any electrical problem in the enlarger (intermittent short or open), this could correct your problem.

Good luck and let the rest of the world know how you solve your problem.

 

[Tom Stanworth]

All appears to be well now. I disconnected all the plugs and connected again in case of a bad connection. Either this was the cure or the bulbs were old and tend to fail in pairs.

Tom

 

[craigclu]

This may be too simple but it sounded as if you were using the enlarger after buying it used? It seems that when used electrical devices are moved, the fragile elements are more apt to be stressed and fail. Even moving an electrical clothes dryer invites a failed heating element. I went through this on two different used dichro heads that had bulbs fail almost immediately after putting them into use. The replacements have continued on with normal life.