Durst M605 - Bulb keeps blowing

[chatanooga]

Hi Folks,
I recently got a Durst M605 (with color head) and it's been quite the pleasure to get prints 'into the hand' this way. Only prob - and a big one of course - is that the bulb is lasting perhaps for no more than 1 or 2 printing 'sessions' ( typically about ten short exposures). Anyone else experiencing similar issues?

Just a bit more detail:
- I'm using the Osram 100W Halogen (6427 HLX EFP).
- This version of the Durst comes with the bulky transformer (EST 305N). I'm measuring a 12.5v AC output at the bulb holder with no bulb connected. The trafo 3pin output connector has markings for 12v and 11v - I'm a bit curious about that since there are only 2 pins in use within the Enlarger itself.
- My exposure times seem extremely short by what i generally hear. I'm printing 6x6 negs to 4x4 inches and my typically exposure times with a grade-3 filter are about 2 seconds. I mention this as I've seen some chatter suggesting that Halogens do not like a very short on time. (I'm using a smart-plug on the transformer mains input as the timer control so the actual values may be slightly different to this, but based on the prints, they are certainly consistent).
- I replaced the original ceramic bulb holders. Twice. The first ones could be heard arcing after a minute of focussing, and then seemed to lose all contact. The bulb itself was still fine. Got another brand and that issue went away. But then in the next session I heard the dreaded 'zssst' mid exposure and this time the bulb was gone.
- I've been careful handling the replacement bulbs. Gloves, etc.

So, kind of at my wits' end. I've ordered the 75W equivalent of the above, and even a 50W LED version. I'm only interested in B&W so maybe a LED would be ok.

Any advice, suggestions would be very welcome!

 

[koraks]

Hi, welcome to Photrio and sorry to hear you're having trouble with your Durst enlarger.

The problem sounds like the power supply.

the bulky transformer (EST 305N)

These units are becoming problematic due to aging of components. They regularly fail.
There's a few options:
1 Replace with a similar unit in working order
2 Replace with the simpler TRA power supply that's not stabilized (which is OK just as well)
3 Repair the unit; I assume you're not capable of doing this yourself or otherwise you wouldn't be here...it's not commercially feasible to repair these units due to the labor cost, but if you have a friend who's into electronics and they can work safely on HV circuitry, you might be able to bribe them with a six pack.
4 Replace the unit with a generic 12V SMPS (e.g. a Meanwell power supply). You'll have to wire it up, but that's not rocket science per se.

I'd go with option 2 or 4 depending on which is cheapest and easiest - which in practice most likely means option 4.

I'm printing 6x6 negs to 4x4 inches and my typically exposure times with a grade-3 filter are about 2 seconds

That sounds pretty normal for modern VC papers like Fomaspeed etc., a reasonably thin negative and a fairly large aperture like f/8 or so.

Halogens do not like a very short on time

A bulb in this enlarger will typically last for years. If it doesn't, something's evidently wrong and it's not an inherent issue of the bulb type.

There's a reasonable chance the LED bulb might survive depending on its power supply arrangement (which is internal to the bulb).

 

[Sanug]

I would highly recommend option 4. A regulated DC power supply will be the best choice.

 

[chatanooga]

Appreciate the detailed replies. Yeah, it does seem to point to the PSU. I'll probably look for a small DC psu as you suggested. I'm curious though in what way it has gone bad - it clearly is able to drive the lamp, but maybe it has gone out of regulation in some way and is sending too high a voltage into the lamp. This isn't apparent from a simple multimeter measurement though.

And keep myself reminded that the goal is photography, not electronics 'research'...

 

[koraks]

There are a few ways in which these PSU's can create spurious spikes or surges on their outputs. A simple multimeter won't show this. Even with a scope you'd have to capture it at the right moment if it's an intermittent issue, as seems to be the case with yours.

Unless you want to maintain a 'period correct' setup (for which the only reason would be a sentimental one, really), I'd not bother trying to fix it and just move on to a modern substitute. As you said, you're in it for the photography/printing, so skip all the fuss and take the straightest route towards a proper solution.

 

[chatanooga]

There are a few ways in which these PSU's can create spurious spikes or surges on their outputs. A simple multimeter won't show this. Even with a scope you'd have to capture it at the right moment if it's an intermittent issue, as seems to be the case with yours.

Unless you want to maintain a 'period correct' setup (for which the only reason would be a sentimental one, really), I'd not bother trying to fix it and just move on to a modern substitute. As you said, you're in it for the photography/printing, so skip all the fuss and take the straightest route towards a proper solution.

Yep. Sensible talk. And I definitely have no sentiments for that ugly trafo. It's such a contrast to the elegance of the enlarger.

 

[koraks]

Yeah, it's an ugly box, too. I know; I've had a few myself. You could gut out the connector and build a box of your own around a new off-the-shelf DC power supply.

 

[chatanooga]

Power supply ordered. In the meantime I tried a 50W led (Osram with a 36 deg angle). It is ludicrously dim. I could probably focus for 5x7 but would think anything bigger would be nigh impossible. Maybe not - I was not on max aperture - it is not great but not unfocussable either. Will give a print a try.

 

[koraks]

a 50W led

The labeling on LED bulbs can be misleading. This is likely a ca. 7W bulb.
Plenty of people use LED bulbs in enlargers to good effect; they're plenty bright, too.

 

[Lachlan Young]

The lamp socket seems to be an area which can cause all sorts of problems - Durst printed on many of their heads that you should replace it every 5 bulbs - and I've seen the results of not doing so (the socket will arc and crack spectacularly) when subjected to prolonged repetition of very short (0.5-1s) exposures - which the current bulbs don't seem terribly keen on.

 

[chatanooga]

The labeling on LED bulbs can be misleading. This is likely a ca. 7W bulb.
Plenty of people use LED bulbs in enlargers to good effect; they're plenty bright, too.

Spot on. In fact the labelling states '6.5w = 5OW'. Actual manufacturer/ part-code is LEDVANCE/ AC45629.

 

[chatanooga]

The lamp socket seems to be an area which can cause all sorts of problems - Durst printed on many of their heads that you should replace it every 5 bulbs - and I've seen the results of not doing so (the socket will arc and crack spectacularly) when subjected to prolonged repetition of very short (0.5-1s) exposures - which the current bulbs don't seem terribly keen on.

That's interesting. Someone posted on another thread here a workaround - basically a permanently soldered bit of brass on the lamp pins!

 

[Ian Grant]

The lamp socket seems to be an area which can cause all sorts of problems - Durst printed on many of their heads that you should replace it every 5 bulbs - and I've seen the results of not doing so (the socket will arc and crack spectacularly) when subjected to prolonged repetition of very short (0.5-1s) exposures - which the current bulbs don't seem terribly keen on.

That has been my experience, not just with Durst enlargers. I remember replacing a socket and the bulbs stopped blowing. I cleaned the sockets on my De Vere 5108 and that helped.

Ian

 

[Lachlan Young]

That has been my experience, not just with Durst enlargers. I remember replacing a socket and the bulbs stopped blowing. I cleaned the sockets on my De Vere 5108 and that helped.

Ian

Indeed, but De Vere at least designed their dichroics to enable socket replacement at speed without having to do anything other than open the service hatch (or dismantle the head, yes LPL, I'm looking at you).

Given that Durst Pavelle and De Vere were (at the time) essentially based either side of Croydon, it's interesting to see what design/ manufacturing/ serviceability decisions they made, roughly in parallel with each other (after Pavelle's innovation of the technology).

 

[koraks]

Replacing the socket is definitely a good idea. Then again, he mentioned he already did that:

- I replaced the original ceramic bulb holders. Twice. The first ones could be heard arcing after a minute of focussing, and then seemed to lose all contact. The bulb itself was still fine. Got another brand and that issue went away. But then in the next session I heard the dreaded 'zssst' mid exposure and this time the bulb was gone.

Spot on. In fact the labelling states '6.5w = 5OW'. Actual manufacturer/ part-code is LEDVANCE/ AC45629.

Yeah, that might be a little lean for a MF enlarger. Something like 20W or so would probably be OK. More is nicer. The thermal design of the head allows for a much more powerful light source to be used in there, but at some point you have to start customizing things as the thermal design is intended for bulbs that are OK running hot. LEDs don't like to run hot.

 

[Lachlan Young]

Then again, he mentioned he already did that

The halogen lamp will not enjoy sub second exposures to build up a test strip for a 2s final exposure, even if there are only 10 final exposures in a session. I've seen people kill halogen bulbs in very similar ways. The only reliable way to deliver short burst exposures is with shutter control via a press-type shutter or something onboard in the chassis.

It's also general good practice to aim for about a 4s minimum exposure to ensure you're clear of any high intensity reciprocity non-linearity (leaving aside bulb start-up issues)- products like Ilford Multigrade Express are intended for very short exposures, whereas the other enlarger-speed papers are really meant for longer (2-4s and upwards, from recall) exposure.

 

[Ian Grant]

Indeed, but De Vere at least designed their dichroics to enable socket replacement at speed without having to do anything other than open the service hatch (or dismantle the head, yes LPL, I'm looking at you).

Given that Durst Pavelle and De Vere were (at the time) essentially based either side of Croydon, it's interesting to see what design/ manufacturing/ serviceability decisions they made, roughly in parallel with each other (after Pavelle's innovation of the technology).

Pavelle/later Durst UK were (well offices) in Church Road, Epsom, not far from the Stranglers Arm. The locals name for the pub after an incident between the Landlord and his late wife. Mu Aunt and Uncle lived a few doors away.

But we forget how important Kurt/Curt Jacobson was to modern colour photography, he introduced the Dichroic head for colour printing. Ron Mowrey (PE) said Eastman Kodak held him in very high regard.

Ian

 

[Melvin J Bramley]

There are many power supplies out there of varying voltages that can be used.
Just adapt the electrical socket and use the appropriate bulb.