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]

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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.
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[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.

[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.

[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 (https://www.dropbox.com/s/7gsq8btauqoh2l9/Backside_EST301.jpg?dl=0)).

@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 (https://www.dropbox.com/s/8tnscrzwi3zdzhq/Inside_EST301.jpg?dl=0)). 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.

[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

[Luis-F-S]

I believe that the EST 301 is "stabilized" while the TRA is a transformer. They pretty much do the same job. Like Michael said the 301 works well on a 138 n is a bit underpowered for 810. If you rewire I would use an external blower and run it all the time like DeVere does.

[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.

[Luis-F-S]

Like an LPL 4500 series with a VCCE head !

[jp0186]

I think I will give it another try and sacrifice one more bulb in the interest of science. If it blows I will follow Drew's and LabRat's advice and connect the bulbs in series to the main without the EST301. For my next batch I will try to source some 'quality' bulbs, need to find a European supplier to save on shipping.

@Michael: Why do you think that a 'light' enlarger is better for printing from 4x5 negatives? In terms of ease of use I find the Durst 184 better than the DeVere 504 that I am used to. Floor space is not an issue in my case. Interestingly, 'beasts' like the 184 or the 138 tend to be cheaper than the classic 4x5 enlargers which in the tiny Swiss market fetch $1000+.

[Michael Kadillak]

I think I will give it another try and sacrifice one more bulb in the interest of science. If it blows I will follow Drew's and LabRat's advice and connect the bulbs in series to the main without the EST301. For my next batch I will try to source some 'quality' bulbs, need to find a European supplier to save on shipping.

@Michael: Why do you think that a 'light' enlarger is better for printing from 4x5 negatives? In terms of ease of use I find the Durst 184 better than the DeVere 504 that I am used to. Floor space is not an issue in my case. Interestingly, 'beasts' like the 184 or the 138 tend to be cheaper than the classic 4x5 enlargers which in the tiny Swiss market fetch $1000+.

The smaller lighter enlargers are considerably easier to work with. Unless you have a 15 foot ceiling you are likely going to be doing a lot of bending over with the floor standing units which can easily be put at an operations access point that is very comfortable to work with. Spend four + hours printing in a session and you will get a taste of what I am talking about. Could this possibly be one of the reasons the classic enlargers are commanding a premium? Maybe you could broaden your investigative reach in this regard. I just acquired a like new Omega D5500 with an Ilford 500H multi contrast head and three Nikkor enlarging lenses for $100. And I have a Durst 138 with the same Ilford 500H multi contrast head on it. Yes, I could have used the 138 very effectively, but the Omega is much easier when I work with 4x5. Over the years I have gained an appreciation for efficiency and operator comfort in the darkroom. I have been where you are and I am just raising some issues for you to consider. How you proceed is completely your decision.

[Drew Wiley]

Gosh, I disagree with you, Michael. Yeah, if you are trying to make a 30X40 inch print from 8X10 film using a 184, you need a 240 lens and will have the baseboard all the way down. But 4x5 is a completely different story and quite convenient, as are smaller enlargements from 8X10 itself. I'll admit that I generally print 4X5 and smaller negs using a 138 chassis instead, but that's just because I tend to dedicate my bigger enlargers to actual 8x10 use. When these true commercial Durst machines are all tuned up, they're a joy to work with. Nothing fabricated with anodized aluminum has that kind of precision or long-term durability.

[Michael Kadillak]

I can see where you are coming from Drew. "When these commercial machines are tuned up they are a joy to work with". Two things along these lines. First is that they are indeed commercial machines and assume a certain level of commercial experience in knowing how to tune them up, knowing the lenses to use and most importantly knowing how to print so you have some reference as to getting the most out of the process. Working with as you say with fabricated anodized aluminum is a right of passage I see no differently as the waste paper bucket you have to fill with crap prints before you know what the hell you are doing. Experience is the operative word.

[Drew Wiley]

Avoid Chinese-made bulbs like the plague. I prefer Japanese-made Ushio bulbs. True US-made GE bulbs are also good, but most of what they GE label for mass-market and home-center sales is imported utter trash. There are also good EU-made bulbs. I only deal with dedicated bulb houses. Photo and AV suppliers tend to rebrand things at an obscene markup, or just substitute junk at a lower price point.It's important to replace both bulbs. One weak one can make the other one pop. Be sure to check for corossion on the sockets too.

[Drew Wiley]

Michael - folks down the street spend their time refurbishing speedboats and classic motorcycles. I liked restoring commercial Dursts, and even built a much larger enlarger from the ground up. 184's and 138's were ideal for my personal skill level and limited shop. Durst made some fancier machines; but I'm what electronics hobbyists contemptuously refer to as a "fuse-puller" - someone who simply replaces suspect components rather than diagnosing them. And I know how to replace a lot of temperamental circuitry with a bit of basic engine wire and a dedicated outlet. The less electronics, the better. I still have one Omega chassis here too, but took it out of service a couple years ago. The big solid baseboard on the Dursts double as outfeed tables for my mounting presses, etc. The 184 is equipped with precise ht adjustment and focus motors. But I would never opt for one of their auto-focus systems, which are known to be flaky, and require odd dedicated carriers. But the refurbishing phase of my life is likely over, and now I just want to enjoy these machines. No space left for another enlarger anyway.

[Luis-F-S]

I've bought lots of NOS American or Japanese ELH's at auction and have never had issues with them. Sometimes the contacts may be a bit oxidized, but a bit of sandpaper takes care of that and I use a small dab of dielectric on the posts. I print down to 135 on the DeVere 5108 but can also use the LPL 4500-II. I like the Devere much better than the Durst which I still have. L

[LabRat]

An ELH bulb tip...

A common use for ELH's was Kodak carousel projectors, so if you are looking for NOS bulbs, the vintage GE projection lamps are common, so some supplier catering to vintage AV or commercial lighting might have a stash... There's a smiling retro girl with a projector on the box... ;-)

Good Luck!!!

Steve K

[jp0186]

After frying another bulb I decided to do the suggested conversion and wired the bulbs in serial. This indeed seems to work much better. I will now control the lights straight through the timer (once I get my hands on one that can handle the 600W). Unfortunately, in this setup I would have to control the fan manually.

Does anyone know if the EST301 just switches on the fan whenever the lights are on, or does it do something more elaborate (e.g., measure temperature or let the fan run for 20s after the lights were on)?

[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

[plaubel]

Looking at my Durst documents again (accessoiries for Laborators), there have been parts ( LaCoLi) for using either with 125Volt, 140Volt, or 160Volt.
This could be a hint...

[plaubel]

Henning, if the "black cylinder" is shown after openeing the cover byside and after removing the "Mischschacht", then this should be a Thermostat / thermo switch S1.

On, and off, in my understanding, at the edge of 80 degrees Celsius says the manual of the CLS 300.
As far as I know, the cables there function as a Widerstand, whats the english name, resistator ?
From my diagram of the CLS 300 they must have a length of 80mm .

I will offer the complete documents to the forum, step by step, please have some patience, I now have to work a bitt.
To be continued,
Ritchie

[plaubel]

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[Drew Wiley]

The fan was originally meant to start automatically when you turned on the power supply. If you split circuits, you'll need to remember to do this manually. I use a dedicated footswitch. New generic power supplies can also be employed. The original Durst units very slightly reduced bulb voltage to prolong their life; but ELH bulbs can be so durable compared to most enlarger bulbs, that this is a non-issue, as far as I'm concerned. There were also minor conveniences in the circuitry like dimly lighting up the filter dials on the color head that are superfluous.

[ic-racer]

Does anyone know if the EST301 just switches on the fan whenever the lights are on, or does it do something more elaborate (e.g., measure temperature or let the fan run for 20s after the lights were on)?

In a non-commercial setting, the fan on my CLS2000 head only runs when the lamp is on. There is a thermistor circuit to keep the fans going if things get hot. The fans only stayed on after I did a bunch of non-stop exposures for test strips to check the filters. In all other cases, the head cools down on its own between prints.

One could easily run the fans from a switch by your timer. Flip it on before exposure and flip it off after exposure. For ten bucks you could mount a remote-sensor electronic thermometer in the head just to be sure.
170777

Since you asked about fans, I'll relay other information from my darkroom

Philips 150 about 80W: Cooling fins, No fan
Minolta Mod III about 80W: Cooling fins, No fan
Omega D5500 200W: Fan runs all the time

[Drew Wiley]

The fan in this case is nominal 240V, while the lamps are 120V. But even if they were the same, the combined wattage would be too much for most conventional darkroom timers. This is a commercial machine for which colorheads up to 2000 watts were made. I've rebuilt those monsters too.

[Luis-F-S]

My recollection is that the fan ran when the head got hot. I can't recall if it ran when you first turned the lights on to print, or if it started when the head got hot, and turned off after it cooled down, after the lights shut off. I seem to recall short printing times when the fan never turned on.

You can buy an external fan (which is what the CLS 301 head uses anyway) and run it all the time while printing. Just get a fan(120v or 240v depending on your power) connect it to the head with a flex hose and unplug it once the head has cooled down after your printing session. This is what I did to have a backup the the Durst Lafan.

On my DeVere 5108, the fan runs continuously when you turn on the power supply. May not be as elegant, but is probably more reliable.

[ic-racer]

Good working timers can be expensive and/or hard to find these days, maybe run both the fan and head from a contactor.

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[jp0186]

Luckily, the Durst LAFAN came with the enlarger so it's more a question of how best to control it. It only pulls 55W so it might be possible to have it running in parallel from a big timer. The RH Designs one seems to still be available and has an output of 750W, which would cover the 2 bulbs and the fan. Unfortunately, it is a little pricey and it would only run the fan whenever the bulbs are on.

I like the idea of a contactor to switch the fan and the head. It seems more involved but it would give me the option of adding adding a temperature control...

[Drew Wiley]

You are not obligated to use the on-board fan. It's convenient and relatively quiet; but a duct could easily be connected to a remote squirrel-cage pull fan.

[Luis-F-S]

Drew, what are you talking about; there is NO ON BOARD FAN. Have you ever used or owned a CLS 301? The Lafan is a separate fan connected by a duct to the head. Below an SM-183 with a CLS 301 head and fan.


You are not obligated to use the on-board fan. It's convenient and relatively quiet; but a duct could easily be connected to a remote squirrel-cage pull fan.

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[LabRat]

In general, it's not the bulbs themselves that need the fan action, it's the everything else in the head... In fact, the bulbs were designed to run hot, and too rapid air flow over them can cause thermal shock that would weaken their structure, but inside the head can become like an oven, where plastics, wiring, lubes, etc are affected, and metal expansion/contraction + warping can happen, so the fan just pushes the heat from the air inside somewhat... (The parts still get warm/hot, but the cooler moving air around them helps them cool more evenly...) Many well designed heads used to be designed for convection cooling, where there was a intake vent area low in the unit that would draw cool air, but there was a chimney high up in the top where warm air would rise up out of the inside... Parts nearer the lamp area would heat more, but the heat would transfer away through the different metal parts, making the head metal a big heat sink that would get warm, but hopefully not too hot to the touch or stuff inside... (An upgrade for many heads is to figure what metal parts get hottest (and more likely to warp/distort), but where they meet the next metal part/panel, to remove the panel so the junction can be cleaned down to bare metals and a thin layer of heat sink compound is applied there so there is a better transfer of heat there, and throughout the unit...) And to re-position plastic parts, wiring, etc that are more heat sensitive lower in the head if they are not already, and away from the hottest panels/parts...

Many of the "muffin" type fans used in modern gear do not operate at mains voltage, but at reduced voltages fed from a tap in the P/S units, so look at the front of the fan itself and note the listed operating voltage (and if AC or DC), and a small supply (from a laptop supply, wall wart, etc) can be added to be left on during your printing session... You don't need a high volume fan, as you are just keeping the air moving inside the unit to prevent excessive heat build-up, and using a slightly under-voltage supply is OK, as the fan will turn slightly slower, reducing vibration... You should not need a hurricane force wind inside, as the fan is to just assist the "natural" cooling inside the head (and prevent hot air build-up)...

The round, black thermostat inside is a safety feature that cuts-off power if the unit got WAY too hot, but is there more for legal reasons, than operation, but as with any high output head, one should not leave it on longer than it is being used at that moment, give it a rest for 5 or 10 minutes if given a hard use, it got VERY hot on the outside, leave the ON cycles as short as possible, and don't use if you smell burning... (Set an operating ON time limit rule for any head and give it a shut-down break if longer like less than a minute on, etc...)

For rebuild/restoration, you can get high heat (ceramic based) engine paints from a auto or hardware store, or paints used to paint B-B-Q grills, DO NOT use vinyl replacement wire as it is not heat resistant, burns easily (like a smoky NASCAR rubber fire), while stinking like hell... Get some teflon coated wire, but note that teflon will just melt above 5 or 600 deg F, so no wires near the lamp or very hot areas... Get those fiberglass covered high heat tubing pieces for wires that run past or through very hot areas (don't allow wire insulation to touch or run along metal or anything hot inside)... After painting, there might be some smell from new paint out-gassing, but normal... Alway sniff for new weird smells when using... Run the head for testing before a printing session and check inside for melting, before a date in the dark...

The voltage regulation issue of the old P/S is only valid if if you use very short exposure fast color materials, or if you live somewhere that has terrible mains power (lights in your house dim/flicker often etc), but for B/W larger prints, the times are longer so a slight variation in power during exposure is negated, esp as mentioned, the head might be a little underpowered, but that helps you a little there, too...

Good luck with the restoration!!!

Steve K

[jp0186]

and don't use if you smell burning... :)

When I rewired the head to serial I managed to use the existing wires apart from a small bit where the main runs into the head. Good idea to replace that with a teflon-coated cable just to be sure.

If the bulbs are not the main issue regarding the fans, I might install a little temperature monitor as per ic-racer's suggestion to make sure there is no heat build-up close to where the wires run. The thermoswitch in the CLS300 cuts the power at 80+ deg C (according to plaubel's manual) so anything south of that should be safe, assuming it's the same switch as in the CLS301. It's positioned next to the connection terminal.

[plaubel]

I want to mention that all the problems of underpower, heat and big fans can be avoided with an LED head.
Today, I wouldn't spend my money in the restauration of a broken EST for b&w only.

Ritchie

[plaubel]

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[plaubel]

...

[ic-racer]

I want to mention that all the problems of underpower, heat and big fans can be avoided with an LED head.
Today, I wouldn't spend my money in the restauration of a broken EST for b&w only.

Ritchie

I'm probably not looking in the right place, but were would one find a MR16 LED to match the ELH output of 300W? And why, when ELH is less than $10.

[Luis-F-S]

I'm probably not looking in the right place, but were would one find a MR16 LED to match the ELH output of 300W? And why, when ELH is less than $10.

++1!! Not to mention the spectral response

[LabRat]

I'm probably not looking in the right place, but were would one find a MR16 LED to match the ELH output of 300W? And why, when ELH is less than $10.

DUAL ELH 600W !!!

Steve K

[plaubel]

I'm probably not looking in the right place, but were would one find a MR16 LED to match the ELH output of 300W? And why, when ELH is less than $10.


Sorry, I really have no idea where to by the LED equipment, because I have no need thistime.
If my EST will give up, I could switch to my condenser type Durst enlarger.

But if I'm not totally wrong, Watt stands for energy and not for illumination.
Maybe this is the reason for Mr. Heiland or people in this forum building bigger LED heads with LED's probably found in the right place.

[Luis-F-S]

I'd still use an external fan when printing regardless just to keep things "cool". I use it on my SM-183 condenser head even when using bulbs smaller than 300 watt. I also use a dimmer on the bulbs to lower output. It's cheap insurance. Only time I don't turn it on is when using the cold-light head in place of one condensor. L

[plaubel]

I also use a dimmer on the bulbs to lower output. It's cheap insurance.

Yes i do the same with my condenser type, and the older opal bulb lasts longer.
They need 220V, but since a longer time we get 240V, which causes old bulbs to become a sputnik.

[tiziano doria]

hi Jp
have you ever found the wiring diagram of this transformer?
I too would need it badly. Mine is out of order and I don't know how to fix my problem. Thank you very much

[Drew Wiley]

Going way back to a comment I failed to answer five years ago, I not only own one of these setups but have fully reconditioned it. I already explained that on the first page of this thread, way back. These came with an internal fan right behind the light mixing box. A secondary external fan would essentially be a booster, or else a makeshift replacement if the internal fan were no longer functional. Perhaps some units were sold without an internal fan already in place, which is too bad, since the internal version is far quieter and more efficient than an external booster.

I greatly simplified things by totally bypassing the original transformer and power supply. Since the units being marketed in the US were dual voltage, with everything running on standard 115V except the fan, I simply split the circuits and hard-rewired them for their respective line voltages, since I already have both 115 and 230 V outlets in the darkroom. No problems. But if rewired for direct current (all you really need is a continuity tester), then it's simply a matter of matching the bulbs to the specific line voltage. No fancy electronics needed.

[koraks]

I greatly simplified things by totally bypassing the original transformer and power supply.
I'm not sure if I'd recommend removing the transformer unless a dedicated 1:1 separation transformer is fitted to the device in its stead.

Btw, 'rewiring for direct current' is a bit of an awkward formulation; I assume you're still running the unit at AC and not DC, but you mean you hooked it up directly to your wall outlets, bypassing its power supply. As said, this isn't good practice and I wouldn't recommend it.

[Drew Wiley]

Lots have people have rewired them, Koraks, bypassing troublesome old power supplies. In fact, my incoming utility voltage is even better regulated than a secondary device would do it. I did that even with my first Durst, which was an older 2000W unit. Saved me hundreds of dollars and innumerable headaches. And of course, it's alternating current. DC hasn't been used in utility lines since the time Thomas Edison was personally alive, and lost most his business to Westinghouse, the father of AC.

I don't need all the bells n' whistles of a master control box in this case. I already have other enlargers loaded with electronic features, and although I do have real uses for all that, it's also what is most problem prone. A Durst CLS 301 is more like a refurbished old military tank. You just want it to keep running without any unnecessary fuss.

[koraks]

It's not about bells & whistles or quality of line regulation. It's a safety issue. The industry pretty much stopped making non-isolated equipment decades ago with the exception fo some plastic-cased adapters, but even these (eg phone chargers) generally have galvanic isolation too, these days. There's a reason for this, you know. I have no doubt it works what you did. I still would NOT recommend it.

The days of the filaments of Philips PL-series valves out in series straight on the line voltage in consumer radios to economize on a smallish power transformer are long gone; I'm sure that's actually a sign of progress.

[Drew Wiley]

The relevant ELH direct 115V bulbs for the colorheads which were marketed here are still abundant. Generic step down transformers to 115 or 120 are also readily available if one needs that kind of thing. As far as re-wiring, I'm confident I've done it even better than the original. I use true high temp truck engine wire. I go overboard on safety. Please keep in mind there are plenty of people on forums like this with some kind or another of serious shop or industrial skills. I've outright made colorheads way larger and more sophisticated than a CLS301; it's a piece of cake to restore, comparatively.

[koraks]

Regardless if the wire you use, you're running a piece of metal equipment that you're physically intimate with whenever you work with it without any means of galvanic isolation. This is not a light bulb in an armature suspended from the ceiling. Anyway, I'll leave it at this; I'm glad you're still among us. I sure have done a lot of stupid stuff in my life too; fortunately for us we usually get away with it.

[Drew Wiley]

Gosh you must think everyone is indeed dumb and uneducated, Koraks. Nobody knows how to even properly ground equipment? Learning correct wiring is routine by age 16 when you grow up in farm country, especially when your own father had a background supervising giant Federal projects. I ran a rural agricultural electric store largely by myself the summer I was 15. What the heck would I know? - Then, prior to retirement, I was in charge of the distribution of the largest selection of Euro power equipment in the western half of the US, with an adjunct major repair service and giant shop with 6-gauge wiring in it (no, that's not a typo - 6 ga, not 16). I know certain things about the evolution of equipment housings you've probably never heard of.

But you are welcome to bid on my other "lightbulb" when I'm too old to use it, which dwarfs the Durst L184. And no need to worry about a metal housing there - the colorhead housing is machined black phenollc from 1/2 inch thick sheet stock, and you need a block and tackle system to remove it. And yes, even that is totally grounded. Incidentally, my own darkroom complex and house were rewired by our company electrician and his crew - Industrially licensed, not just residentially.

[koraks]

I feel that the discussion is moving away from the topic and is now about credentials, reputation and in the background, ego. I'm not interested in that direction. I don't doubt the validity of your knowledge and work experience.

[Drew Wiley]

I'm sure there are a number of people on this forum who know far more about wiring and electronics than I do, Koraks. Re-doing a CLS301 really isn't all that hard for anyone who knows some basics and owns a continuity tester and multimeter. It can be a lot simpler and less expensive than repairing an old complicated power supply. But those too can simply be ordered new and customized from various commercial sources. It need not be Durst per se, though the sheer replacement route can be somewhat expensive.

What is a lot trickier is cleaning old internal dichroic filter banks without harming them. I did that too, plus total cosmetic restoration of the whole machine, clear back to 100% operational functionality and 95% cosmetic. Certain changes along the way - a black laminate baseboard instead of white, new bellows, a fully interchangeable copystand option with integral lighting, and a masking blade system for the easel suitable up to 30X40 inch prints, even found some mint condition pin registered extra carriers, plus AN glass for those. Overall, a fun project. But people in this neighborhood put in far more time and money restoring motorcycles and speedboats and old cars. Just like any other fix-it hobby if you have the right shop equipment.

[ic-racer]

Where I work we use isolation transformers on many items, but I never had the urge to setup any in my home darkroom. I'm careful about spills and wear the same type of non-conductive silicone clogs on my feet and have GFI breakers. One can read up on GFI vs Isolation Transformer and draw one's own conclusions about safety.

Even with an isolation transformer or GFI things can still go wrong if one has contact with wires on each side of the load, so neither will eliminate the need for conscious safety.

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[Drew Wiley]

Common GFI's aren't adequate for cumulative high wattage applications. You need it in the distribution panel itself. My enlargers are all in dry spaces totally separate from the sink room. And in terms of hypothetical fire risk, even my ceiling have FRP (fire-resistant fiberglass panel) installed above and behind the colorheads. Hot air is exhausted outside the building by pull force, and not just internal colorhead fans. In the sink room, my footswitch for temporary safelight operation is totally rubberized and waterproof - no risk of corrosion or water penetration. All kinds of things can be done to improve safety.

But something must be terribly terribly wrong if someone manages to electrocute themselves with an operational enlarger! Maybe if they walked over there with dripping fingers and punched some buttons on something not properly grounded or GFI'd. At a minimum, a darkroom should have a "dry side" well spaced apart from the "wet side". In any event, I've never even heard of an enlarger accident of that nature, even in carelessly supervised High School and rental darkrooms. Professional electricians getting fried by other things, yea, especially linesmen doing repairs during electrical storms, or once in awhile someone doing a major high voltage industrial job and getting casual - that I have encountered. But a basic darkroom, in this day and age when a 20-amp wall GFI is dirt cheap and suitable for at least amateur enlargers? It's drymount presses that especially need serious wattage and wall wiring.

And those of us who do work with commercial-grade enlargers also understand commercial or industrial grade wiring requirements. The two go hand in hand. My darkrooms and shop spaces are in a renovated small commercial building, having dual-voltage and a separate panel all along, and now further reinforced electrically. There's nothing particularly exotic about that. People like me routinely look for that kind of thing when buying property in the first place.

I forgot to mention copper thieves. Sometimes they try to steal live overhead utility wiring from the poles on the streets - a type of criminal awfully easy to catch and bag if they do it wrong (body-bag, that is).

[ic-racer]

But something must be terribly terribly wrong if someone manages to electrocute themselves with an operational enlarger!

Yes!

[Drew Wiley]

I was trying to figure out what all of Korak's fuss was about. There are no capacitors in the colorhead per se, and wholly unplugged, even from the power supply, an entire rewiring needs only a basic continuity tester, which is what? - in mine, a single AA battery and little light bulb, plus a probe, and an extension of tiny speaker wire with a little alligator clip on it, rather underpowered to electrocute even a spider.

And in use, every day of the week there is hypothetically greater danger from a basic hair dryer in a wet bathroom. That's why CFCI's are code. Coming from a shop background where the incoming voltage was 440 3-phase before step down, a 115V printing device with two 300W lightbulbs in it isn't so frightening. No, that's certainly not my most powerful colorhead by a long shot; but any serious shop space begins with an ample power supply and grounding. Most kitchens require far more juice than a typical home darkroom.