CLS 301 Restoration

[jp0186]

Hi all. I recently acquired a Durst L184 base with CLS301 head and am trying to get it to working order. Unfortunately, the bulbs that came with the machine did neither have the right sockets nor the right operating voltage to work in the machine. A bit of research showed that the CLS301 model takes 2x ELH 300W/120V bulbs. I ordered some and sure enough they fit into the sockets.

When I installed them everything seemed to work fine for a moment and then one of the bulbs went dead. I opened up the machine and looked at the circuits inside - basically just two bulbs in parallel - but when I measured across the contacts at the sockets they showed a steady 160V (which probably explains the destruction of the 120V bulbs).

The only other component in the circuit is a little black cylinder on the neutral wire (see attached picture, the print on the side says R87-154).

I was wondering if anyone here knows about this type of enlarger head and if the wrong voltage is more likely to be an issue with the power supply or with the (potentially more easily replaceble) black cylinder.

Thanks for your help.

Henning

[ic-racer]

Are you using the EST301? What is the output voltate of that?

[Luis-F-S]

The TRA 301 has jumpers to be set for 120, 220 or 240 current. I would check that first, before you do a complete re-wire as Drew suggests below. There are inputs for both 120 and 240 and the fan runs on 240 v. This was my backup power supply, I sold my EST301 pictured in the post above when I sold the CLS 301 head. The TRA was my backup, which I still have for some reason.

[Drew Wiley]

Should add: most of the power supplies were international. But they'd blank up unwanted plug positions for specific export reasons. The ELH bulbs are more durable than most if purchased from a quality mfg. But they are intended for a 115V circuit, so the voltage must be stepped down to this for the bulbs themselves. Otherwise, the pattern of the sockets on the power supply identifies things, since US NEMA and various European plug and outlet patterns are so different.

[LabRat]

Should add: most of the power supplies were international. But they'd blank up unwanted plug positions for specific export reasons. The ELH bulbs are more durable than most if purchased from a quality mfg. But they are intended for a 115V circuit, so the voltage must be stepped down to this for the bulbs themselves. Otherwise, the pattern of the sockets on the power supply identifies things, since US NEMA and various European plug and outlet patterns are so different.

+1 to use better ELH lamps... One of my color heads uses GE ELH lamps, and even after hard use, they are good for about a year and a half in my head (without a blower)...

I agree with removing the power supply, as Durst electronics are not reliable, and over-engineered to a fault... You can wire the two lamps in series for 240V, and skip the box... But the power supply might be reading high if you are measuring the voltage not under load (without the lamp in circuit)...

Lamp sockets will fail sometimes, so both should be replaced now while you are working on this...

Steve K

[plaubel]

I agree with removing the power supply, as Durst electronics are not reliable, and over-engineered to a fault...

In my opinion, they have been reliable decades ago.
Reading the electrical drawings sounds very professional and brainful.
The Dursts have been sold to thousands of professional photographers who normally preferred reliable equipment.

What we are using today is a 40 to 50 years old electric box, which often layed in dark cellars before.
Not using this units is of course the second reason for a sudden death.


""But the power supply might be reading high if you are measuring the voltage not under load (without the lamp in circuit)...""

This step could be the main reason for killing EST units - I have been taught never to start them without lamps in circuit.

JP, after reading my EST 300 / CLS 300 repair manual twice, there are some possible reasons for destroying your bulbs.
Unfortunately this manual is for german voltage only, but listen, their exist two versions of my EST 301 one for 220 Volt, and another for 240 Volt.
So it may exist 120/140 or other versions?
Check this first, because this results in different control units.
Changing the main voltage results in changing the bulb voltage, which the EST has to avoid via special groups, and maybe one of this groups has too much to do, or is already broken.

I am not able to translate the complete manual, and of course I am missing electrical knowledge, but I am sure that an electric special force could run your 301 after checking and/or adjusting the EST unit.

The main part of your EST is stabilizing the voltage to the bulbs which gives best results to your prints.
Try not to give up this option.

The unit contains thermo control and upheating systems, so after plugging to voltage, waiting for some minutes is required - says the manual.

Best,
Ritchie

[Drew Wiley]

I fully refurbished one of these a year and a half ago, along with the L284 chassis itself. Now it looks and operates like new. The trickiest part was cleaning all the dichroic filters. But my philosophy is that the bells n' whistles of the power supply are redundant. If the unit was intended for export to the US, only the cooling fan needs 240 voltage. So I toss the power supply (which has most of the headaches on older units), and split the circuits, isolating the fan from everything else, which is ordinary 115 voltage. Of course, you want to check your specific voltage fluctuations first, at the outlet, using a good meter. But often residential voltage is plenty consistent. So my fan is plugged right into one of my single-phase shop outlets with a dedicated footswitch, while everything else is on a clean 115V 20amp outlet, with a timer to the bulbs of course. Durst deliberately put the two bulbs on a serial circuit with a jumper wire, rather than parallel-wired, so that when one bulb fails, the other won't illuminate either. A continuity tester is essential to figuring this out.

[Michael Kadillak]

I acquired a CLS 301 with a Durst 184 a number of years ago and I discovered (much to my dismay) that it was incredibly under powered and not the right match for this enlarger. This head belongs on a Durst 138 IMHO. Cut to the chase and get some power on top of the 184 if you are planning to use it to its full potential. Not trying to derail this post, just share my experiences.

[jp0186]

Thank you all for the comments. Great to see there is an active community still working with these old machines.

First off I should clarify, I am from Europe and I have reasons to believe that the power supply and head were also previously operated in Europe.

@ic-racer: On the backside of my EST301 it says it has an output voltage of 120V (see attached picture: Backside_EST301.jpg).

@Luis-F-S: What is the difference between the TRA301 and the EST301? In any case the insides of my EST301 look different from yours in the picture (see image: Inside_EST301.jpg). Couldn’t find any jumper switches.

@Drew: I have to admit that I didn’t realise that the bulbs were a serial circuit with a jumper (although that would explain why when one bulb failed the other went out as well. I assumed I killed both of them at the same time…). Could that also explain why I measure 160V in the circuit?
Perhaps everything is fine with the EST301 and I just had bad luck with the bulb that blew out. When I did my test run the bulbs were running for several seconds. I then switched them off, waited a couple of seconds and then switched them on again, killing one of the bulbs.

@Michael: I am currently only shooting 4x5 B/W and this is my first enlarger, so I am keen to test out how it performs before upgrading to something else. It’s already a big step up from the machines in the community darkroom that I am used to. The fact that it’s reasonably easy to get replacement bulbs (ordered from the US) is also a big plus for my requirements.

[Michael Kadillak]

@Michael: I am currently only shooting 4x5 B/W and this is my first enlarger, so I am keen to test out how it performs before upgrading to something else. It’s already a big step up from the machines in the community darkroom that I am used to. The fact that it’s reasonably easy to get replacement bulbs (ordered from the US) is also a big plus for my requirements.

With all due respect if all you are shooting is 4x5 and this is your first enlarger the amount of overkill is just enormous. These are massive machines that are heavy, tall and everything about them are of of enormous proportions because while they can do 4x5 this is not what they were designed for. I am a strong advocate for using the correct tool for the job. A 4X5 enlarger that would actually facilitate your introduction into enlarging IMHO should be light, small and easy to use and learn from and sit on a countertop. Just my $0.02.