Durst CLS 1840 - Need help and advice :) New Darkroom build.

reneboehmer

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Dear photrio community,
I am in the process of finishing my new darkroom space. Before starting to redo the room, I got my hands on a Durst CLS 1840. The whole darkroom is based on this unit and I plan to use it for the rest of my life. I am reaching out to you since I face a couple of problems.

1) I need to find spare 1000W bulbs for my unit. One 750W bulb is installed and that seems to be working fine, but I am sure it won't last forever. Could anyone provide me with a contact that might be able to sell me some?
2) The reflector in the unit seems to be quite damaged, it flakes off lots of little glasslike dust. Is there a cheap way to get a new one? There is a seller that sells them for almost 400 bucks (incl. shipping) on eBay. I am quite unsure about paying such an amount of money when there might be an alternative.
3) My EST 1000 Power supply had the two paper capacitors blow up. They stank like hell. Any ideas why both the capacitors would fail at the same time? (The 6k ceramic fuse also got extremely hot)

I am thankful for any tips you could give me! All the best! -Rene
 

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ic-racer

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Great setup you have there!

A while back one could get replica reflectors from Russia. That was before the current political situation.
I have the 2000W head on mine. I don't know much about the 1000W lamps. There are a few alternatives I know of for the Thorn 2000W lamp, however.
Not sure about the power supply, it depends on which capacitors. Do you have the service manual?

 

koraks

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reneboehmer said:
Any ideas why both the capacitors would fail at the same time? (The 6k ceramic fuse also got extremely hot)
Click to expand...

Possibilities:
1: Functional and physical proximity; i.e. they're exposed to the same environmental (heat) and load conditions, making them fail more or less at the same time. Especially if they're two caps in parallel (effectively making one bigger cap)
2: Failure of another part (like a thyristor) triggering a cascading failure in other parts.
(You use the 6k part is a fuse? A 6k resistor exposed to 230V would dissipate around 9W; a typical ceramic power resistor would get pretty much glowing hot at this level. I don't see how a fuse would get hot).

#2 would be the worrying one, although the caps blowing would also relate to their age/wear by default.
The best approach to fixing this would be to hunt down a schematic of this power supply and start doing some measurements on various components.

These power supplies are notorious. They're relatively complex, and they're getting long in the teeth. A friend of mine has replaced the 1kW light source power supply on his Durst 8x10 by a generic PWM-controlled thyristor dimmer board; he got tired of fixing the endless stream of defects on his unit.
 
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reneboehmer

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Thanks for your input! Yes you are right, I misstyped and wrote fuse instead of resistor. I am sorry my mothertounge is German. Sometimes I mix up words when writing.
I also read online that these Rifa PME 271 Paper condesators are known to blow up and are to be avoided at all costs. I am not well educated on the matter so for me its hard to tell, what the actual issue is. Both the Rifa PME's exploded and the 6k8 5% resistor got so hot that it undid the soldering. Might bring this thing to a friend who studied electrical engineering.
 
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reneboehmer

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Hello Ic-racer,

Is there any chance you could forwoard me the contact you had in Russia? I might be able to get a couple reflectors smuggled and distribute some here on the forum.

I will try to find some spare bulbs to and update my progess here in this thread to other people who might be on the lookout are able to conact me.

I dont have the service manual! Do you by any chance have one?

All the best! -Rene
 

koraks

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reneboehmer said:
Might bring this thing to a friend who studied electrical engineering.
Click to expand...

That'll be perfect.

Those old paper electrolytic capacitors wear out, yeah. In general, electrolytic caps have a limited lifetime (20 years, give or take a decade or two...) so the fact that they failed in this machine is to be expected.
 
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reneboehmer

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ic-racer said:
View attachment 380245
Click to expand...

This is awesome, almost the same setup as I have. What kind of negative carrier is this? Do you use this professionally or is this your personal unit? I also have a full set of spare Light mixing boxes (Altough the ones I have might have been for the vertical 10x10 unit Durst made.) Also I have one more question for you, I also own a set of Trinomasks, the ones that are intended to be used without glass. They do not fit my normal 10x10 holder. Do I insert them instead of the glass? The holders a slightly smaller than the glass insert area.
All the best!
 

gary mulder

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The Trinomask’s fit into the Laradap. The Laradap replaces the glass in the Rapidinsert. The top part of the Rapidinsert will not be used in this configuration.
 

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ic-racer

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My negative carrier is the Negateil. When the enlarger is used for horizontal projection, the Negateil can shift the negative vertically. This allows multiple horizontal strips of 50" paper to be exposed and later spliced into a massive mural.

With the 2000W head, glass/glass carriers are usually needed as there is a second blower that blows right on the negative carrier.

I repaired two power supplies for the base (EPU1000) and two for the head (EST2000N) but only ran into faulty transistors or resistors.

 
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ic-racer

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The reflectors are mentioned in this thread:

Durst 1840, 184 and 138 enlarger lamps - NEWS !

New OPAL light bulbs for Durst large-format enlargers. Durst used to provide 4 versions of OPAL bulbs for their enlargers with condenser units. They were large and rounded, designed to provide an even illumination of 5x7 and 8x10 negatives. Available in 200W, 300W, 500W and 1000W versions...
www.photrio.com
 
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reneboehmer

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Well, that is very nice indeed! Just such a great enlarger!

I also noticed that two transistors were colored weirdly. It seemed to me that they might have been damaged. I will most likely also replace them when ordering new parts.

Thanks again for redirecting me to the thread that mentions the reflectors. I'll try my best to get some. One of my employees is originally from ST. Petersburg and I am sure he might be able to pick some up for me when he visits family again.
 
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reneboehmer

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koraks said:
This is deceptive; usually, there's no visible damage to transistors that have failed in this kind of device.
Click to expand...

Ok, I see! Excuse myself, my knowledge about these things is limited.
I just made an appointment with my friend, who is the electrical engineer, and he agreed to check the device and swap the parts for me.
 

gary mulder

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The EST 1000 Power supply’s are notoriously unreliable. I stopt repairing them. (For my own usage). I replaced it with a a generic PWM-controlled thyristor dimmer board and a micro processor.
 

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ic-racer

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gary, I don't think I have seen a picture of that setup. Two heads and a single baseboard??
 

ic-racer

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There was a thread a while back about reverse engineering the Durst PRO EST1000, but it looks like you have come up with your own design?

Image: Durst Pro EST1000 Replacement Internal Photo

 

gary mulder

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it looks like you have come up with your own design?
Click to expand...

Yes. I was’t aware that I had already been done. But the Arduno I use can controle the PWM-thyristor dimmer board. By adding a light sensor it’s possible to make a closed loop light source.
 
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reneboehmer

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gary mulder said:
The EST 1000 Power supply’s are notoriously unreliable. I stopt repairing them. (For my own usage). I replaced it with a a generic PWM-controlled thyristor dimmer board and a micro processor.
Click to expand...

Gary, that looks amazing. Can you, by any chance, elaborate a bit on what the functions of your own build are? I am unsure what kind of different functions this unit even supports. In my mind, driving a 1000W halogen bulb shouldn't be very complicated. Excuse my, maybe idiotic sounding question, but an answer would greatly help me understand the unit and would allow me to communicate better with my mate, who's going to fix it.
 

ic-racer

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The EST provides these basic functions to the head after it recieves an ON input from the timer:
Power and timing of the fan including a thermal switch
Regulated power to the lamp, (including low idle current when off)
Power to the shutter and timing for opening and closing

I think that is it, but I hope Gary chimes in with a more detailed description of his masterpiece!
 

gary mulder

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That sums it up nicely. Except that the CLS1840 don't have a thermal switch. Maybe not that evident it also has to make sure that te inrush current from the bulb is handled in orderly manner. The cold bulb resistance is less than 1 Ω ! And also turning off the blower introduces a lot of electronic noise. These two aspects are not very wel addressed in the original EST 1000. Maybe causing the premature failing.
What I left out of my design is delaying the power down of the bulb making it not necessary for repeated powering up the bulb while making test strips in the usual manner. But that’s a software matter in my design. I do not make test strips in the traditional way.
 
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reneboehmer

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Awesome, thanks guys for clearing that up. Gary do you, by any chance, still have a parts list? Id love to build this version of yours, seems way more trustworthy then the original.
I'd be really greatfull if you were willing to share this
All the best!
 
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