Durst M605 Electrical Problem - Explanation Needed

[pentaxuser]

I have a M605 with colour dichroic head which may be irrelevant to the issue but I thought I had better include the information.

I had noticed on the night before last that the enlarger lamp(75W) would momentarily fluctuate in terms of light output on the odd occasion i.e. not every time I was doing an exposure.

I looked inside the lamp housing and noticed that I could make the output fluctuate if I touched the wires which after coming in from the mains supply going into a small junction box, connect to two wires which come from the "female" ceramic holder which pushes onto the two prongs in the back of the lamp. Once the light had been on for a few seconds the blue wire from the mains going into the junction box began to get very hot. So hot in fact that the plastic junction box began to soften.

At ths point I turned the lamp off and examined the junction box. On the side where the blue mains wire is connected via the junction box to the brown wire going into the ceramic holder, the junction box had distorted with heat.

It was time to get rid of the junction box. I couldn't undo the two screws on the hot side to take out the wires. The box had become distorted and the screws seemed to have solidfied and looked rusted.

I cut the wires and replaced the junction box with a standard box and reconnected the wires. I also cleaned out the small holes in the ceramic holder as Stewart Band, late of Nova had said that a form of arcing inside the ceramic holder over months/years built up material which could affect the power from the wires and result in fluctuations in light output.

Once the junction box was changed I switched back on again and apparently no fluctuations and no heat being generated along the wire or in the junction box.

I an no electrician but I had always thought that along as two wires were connected in a junction box that either the electricity flowed or it didn't and that heat generation wasn't possible. but everything that happened seems to contradict this.

So calling al those enlarger experts out there and especially those who are electrically knowledgeable and maybe Durst 605 experts to boot, can you shed any light on this phenomenon?

The junction box is the original and must be many years old but do they eventually wear out and if they do can they cause this sutuation to happen?

Incidentally all four wires both in and out of the box were the tight and the lamp never went out as might be the case if wires were making intermittent contact and yet touching the hot side wires caused the lamp's power to fluctuate.

I am aware that lamps fluctuate when they are about to blow completely and I cannot rule this out as a possibilty but the last time this happened and I had to change the lamp, I don't remember heat in the junction box and I couldn't then reproduce the effect simply by touching the wires. As I recall things the lamp's power fluctuated a few times and then quickly the filament blew and the lamp was useless. This doesn't seem to be the case this time.

I am puzzled and a little worried as without an explanation as to cause I have no idea if I have really solved the problem or whether the heat build up has begun again and I'll be back to square one.

Any help on this would be appreciated.

Thanks

pentaxuser

 

[Nicholas Lindan]

Incidentally all four wires both in and out of the box were the tight

Mmmmm, I'll wager 20 quid "You thought they were tight, they seemed to be tight. Weren't they? They must have been tight. Otherwise ..."

What you describe is a typical loose connection and is very common with halogen lighting systems and seems to be 100% de rigueur in photographic enlargers. The designers of the equipment don't allow for the very high surge currents when the lamps turn on. If the connections are close to the lamps the heat from the lamps compounds the problem. Halogen lamp fixtures themselves are a replaceable item, just like the lamp. The connections suffer heat-cool cycles and the connections work loose over the years. Much equipment is designed without even allowing for the very high steady-state current that low voltage halogen lamps draw all the time.

I wouldn't worry about it, just make sure the fix you put in place looks like at least a 10-times overkill and you will be OK.

 

[Nicholas Lindan]

http://en.wikipedia.org/wiki/Quantum_tunneling

Even when they are not connected, they are connected.

 

[Ralph Javins]

Good morning;

The fluctuations and variations in electrical connections. It is amazing to me that our house wiring is as reliable as it is, although there can be problems even there. Occasionally the Fire Department people will identify as the cause of a fire "faulty wiring." Usually this translates to an electrical connection that has loosened from years of temperature cycling, then oxidation and further increase in resistance, and finally overheating.

This kind of thing can happen inside electrical equipment also. Yes, unplugging the equipment, allowing time for any filter capacitors inside to dissipate their charge, and opening the cabinet the recheck the quality of the higher current electrical connections is a good idea. If you do not feel comfortable doing this yourself, then do not, but take the equipment to a qualified electrical technician or equipment repair facility and have them perform this service for you.

Please note that for industrial electrical services, there are scheduled routine checks made of the equipment, the electrical contacts and wiring, the current draw and voltage of each circuit, and even monitoring the circuit board or panel assembly with an infra-red temperature measuring device to detect spots and connections that are beginning to develop problems and their temperature is beginning to rise. That is a reliable indication of a circuit that needs attention and repair in an industrial setting. It would be a nice thing to afford the equipment to do this with our equipment and our houses also.

I never thought that 28 years of experience working on traffic signals, roadway lighting systems, electrical power services, pumps, pump control systems, telemetry systems and other public service agency electrical systems would find a useful application in a photographic forum.

 

[pentaxuser]

Thanks for answers. Nicholas.Put it like this. When I cut the wires to free the junction box, the remains of the wires in the box cannot even be freed by pulling with pliers! Maybe by that stage and looking at Ralph's statement the wires had actually melted together. If so I was perhaps only minutes from a potential fire.

The distortion to one side of the junction box was clearly caused by the heat in the wire and not the heat generated by the lamp.

I'll keep an eye on the new junction box and re-check the tightness and even undo the wires periodically to check for signs of oxidation

Thanks again

pentaxuser

 

[Paul.]

Pentaxuser,
Am sure you have cleared the fault, classic case of loose connection causing arcing and overheating. It is helpful if you renew the lamp holder from time to time, I change mine every second lamp, as the spring contacts in the holder anneal with the heat cooling cycle over time and will eventualy burn out.
It is usual to smell a burning connection before it actualy ignites and even then if you turn it off at the plug it should self extinguish once the power/heat is removed, In my experiance 38 years an electrician, I have seen many burned connections with melted insulation but never one that actualy caught fire.
I know the fire statistics talk about electrical faults but I did 10 years as a stand by electrician answering fire calls amongst others and can think of only one fire I could say with any certanty was caused by an electical fault, but if you had seen the state of the rest of the wireing it was amasing the house holder had not been elecrocuted.
If you still have concerns you could have a Periodic Test and Inspection of the electrical instalation and a Portable Appliance Test of all appliances carried out by a competent person Qualified to City and Guilds 2391 inspecting and testing for the instalation and P.A.T. qualified in the case of the appliances. It would not be cheap. In my area £180 for the periodic test and £40 for the appliances.

Hope this of help to you, Regards Paul.

 

[pentaxuser]

Pentaxuser,

It would not be cheap. In my area £180 for the periodic test and £40 for the appliances.

Hope this of help to you, Regards Paul.

Thanks. Sounds like big bucks. I think I'll simply undo the head periodically and check the wires. Your post has reminded me of something. I had been told that the inside of the ceramic lamp holder is also inclined to arcing and that a periodic clean out with a miniture round file small enough to penetrate the holes is worthwhile. I haven't been able to find such a file but have simply scrapped out the inside of each hole in the holder with a large sewing needle.

This won't be as good but presumably will still help dislodge any build-up caused by arcing which will eventually result in resistance and light intensity problems.

Appreciating you are possible the wrong side of the Atlantic to answer but is the ceramic holder peculiar to Durst enlargers or is it a universal fitting and obtainable from non Durst sources.

I hope so as items which are peculiar to Durst enlargers and only made for Durst are getting hard to find.

Thanks

pentaxuser

 

[pentaxuser]

Sorry Paul Re-reading your post and seeing figs quoted in £'s, I now assume you are UK based so any sources you know of for ceramic holders for Durst enlargers would be pertinentand very useful.

Thanks

pentaxuser

 

[Nicholas Lindan]

the inside of the ceramic lamp holder is also inclined to arcing and that a periodic clean out with a miniture round file small enough to penetrate the holes is worthwhile. I haven't been able to find such a file but have simply scrapped out the inside of each hole in the holder with a large sewing needle.

The large sewing needle is not a good idea, neither is filing in general. The bulb socket contacts are most likely nickel plated phosphor bronze. When you remove the oxidized nickel the bronze below will corrode even more quickly. The holder/dichroic reflector should be treated as a disposable, just like the bulb.

The proper file to do what you should not do is a 'Swiss Pattern Needle File' - ask at the ironmongers. If you were in the US I would send you to Sears. At Amazon: http://www.amazon.com/General-Tools-S475-Pattern-Needle/dp/B00004T7WP

 

[Paul.]

Pentaxuser,
I know Oddysy has the lamp holder for the DeVere enlargers which if I remember correctly is just the push on connection for the lamp and 2 short peices of heat resistant flex to connect to the connector block, the lamp is located by the reflector on my 504. so would assume the lamp holder is a pretty universal thing and would fit or could be adapted to most halogen lamp enlargers. I have found Oddysy to be most helpful and while not the cheapest of suppliers their quality and service is second to none and they won't try and sell you what you do not need, when I first baught my 504 I found I did not have the expected contrast with the filters so rang Oddysy to inquire about new ones, they had them in stock but told me it was more likely that the filters were dirty rather than faded and how to clean them, the filters were over £30 each so x3 ment a saveing of £100 which in all honesty they didnot have to tell me about. Give them a ring I am sure they could help.

Regards Paul.

 

[pentaxuser]

Nicholas and Paul Thanks.

Paul I gote my last ceramic holder from Nova and as they are local (17 miles away) I'd try them first but I'd thought I'd try and find other sources as well, as "bits" for Durst enlargers must be getting scarcer.

Filing, the thing I shouldn't do, would be done on a preventative basis or perhaps NOT based on advice given but anyway ot would be without any science attached.

In general what do I need to look for that tells me when the female ceramic holder needs changing?

Paul. On the filter front you mention, are these the dicroic filters built into the head? If so, I haven't noticed a problem with mine but any idea how you clean or even check the state of the YMC filters on a Durst. It would be great if you could clean them. My understanding is that they must eventually get dirty as everything does but by and large don't actually fade. I always have the nagging doubt that you never know how bad something can be until you do something to improve it. A bit like not realising you are short sighted until the optician tests you and puts the right spectacles on your head.

Maybe filter cleaning is another question for Odyssey?

Thanks

pentaxuser

 

[Paul.]

Pentaxuser,
Yep it was the dicroic filters, on the DeVere they are made of glass and I was able to clean them in situe by takeing the light mixing box out and working from both sides carefuly clean one filter at a time with medical alcohol on a cotton wool swab, lots of changes working very gently, the thought uppermost in my mind was break one of these and it's £30 plus postage and the hassel of stripping the head to fit it.

The results were worth the effort as I got back to the expected times and settings.

Before you try it make sure your filters are glass not plastic as I have no idea what effect alcohol would have on plastic.

Regards Paul.

 

[pentaxuser]

Thanks Paul. I'd need to check perhaps with some Durst M605 experts about the nature of the dichroic filters. As you have said - not worth the risk unless I know what the effect of cleaning would be.

pentaxuser