Strange RA-4 Problem

[Bumba]

Hi, these are my last 3 test strips in order. As you can see something is going wrong. They were all made identically with the best precision I could give. The voltage incoming was very stable give or take 1 volt.

I'm thinking the problem lies in the enlarger itself. I thought the chemicals at first but if it was the chemicals I feel the changes would be consistent or at least predictable.

I'm thinking it's either the transformer, the bulb (it is a new bulb however), the wiring, the bulb connector. Any idea how to test these or any ideas what's happening? My enlarger is a Durst M370 connected to a TRA 305 transformer and a TIM 60 timer.

Thanks

 

[pentaxuser]

I can't help but feel I have seen these before. Did you use these shots before but to illustrate another problem? Are any of these close to what the scene's colours were? Never having seen the scene in real life it looks as if the middle one may be closest to what the scene's colours were.

So just to be clear you are saying that these are test strips exposed in the above sequence( if not what order was used?) with the same filtration and presumably different exposures but the same new bulb and same chemicals to develop and all three were developed within minutes of each other?

Thanks

pentaxuser

 

[kevs]

Did you accidentally remove the colour filters from the light path or forget to switch them back in after white-light focussing?

 

[Bumba]

I can't help but feel I have seen these before. Did you use these shots before but to illustrate another problem? Are any of these close to what the scene's colours were? Never having seen the scene in real life it looks as if the middle one may be closest to what the scene's colours were.

So just to be clear you are saying that these are test strips exposed in the above sequence( if not what order was used?) with the same filtration and presumably different exposures but the same new bulb and same chemicals to develop and all three were developed within minutes of each other?

Thanks

pentaxuser

Hi Pentaxuser, you've definitely seen these before as I'm having problem upon problem in my darkroom unfortunately. Everything was the same including exposure time and filtration. In theory they should all be identical. The top was the first one I made and the bottom the last one I made. The middle is the closest to what I'm after but the density is a little under.

Did you accidentally remove the colour filters from the light path or forget to switch them back in after white-light focussing?

The filters were in place for all three of these

 

[Bumba]

My last bulb had corrosion on the terminals. Could corrosion on the bulb holder cause these kind of problems. Anyone know how to open up one of these holders?

 

[pentaxuser]

Bumba, I will take it that in the absence of any rebuttal of my statement, you used the same filtration of Y and M in all three strips but presumably the exposures differ The order in which you made the exposures were as you have stated so it went from "worst" to nearly OK ( the more grey floor) then back to "worse again" What were the three exposures, just as a matter of interest?

I also take it that they were all developed one after the other i.e. within minutes of each other. If I have described everything that happened accurately then as far as I can see what appears to have happened has no reason to happen.

I cannot say what a large change in bulb illumination during the test strips might be able to do such as change the colour balance but I'd have thought that such a change in illumination would have been seen by you.

It is almost as if the dichroic filters were at the worst setting i.e. the setting you chose just prior to the first exposure then by themselves moved to the best then slipped again but not quite back to the worse setting that you had made I take it that you have a dichroic head. If you used a filter tray then the filters cannot move so as unlikely as my previous scenario is, it then becomes impossible

I just don't have an explanation that can reconcile the problems with the procedure you describe

If it is a dichroic head then all I can suggest is that you examine the M and Y dials by zeroing all 3 then moving each in turn from 0 to max checking if each changes as you increase the setting. Then choose any setting or better still the setting you used and switch the enlarger on and off three times checking each time if colour cast changes by itself

I hope that others here can come up with suggestions about the cause that explains what you experienced. Frankly I am now out of ideas

pentaxuser

 

[pentaxuser]

I have just seen your #5 now You can't open up these ceramic holders and it can be very difficult to detect if there is corrosion inside the holes. Ideally it is best to change the holder each time you change the bulb. The ideal instrument to clean the holes is a large sewing needle or a jeweller's round file but this is a second best solution.

However as I said in #6 if the ceramic holders are corroded then you should see this as a fluctuating illumination during exposure.

pentaxuser

 

[perkeleellinen]

I'm having problem upon problem in my darkroom unfortunately.

Bumba - You're within driving distance of Secondhand Darkroom Supplies in Oxfordshire. Maybe these frustrations you're having are frequent enough to consider buying a new enlarger:

https://www.secondhanddarkroom.co.uk/product/durst-370-colour-enlarger/

 

[Bumba]

Bumba, I will take it that in the absence of any rebuttal of my statement, you used the same filtration of Y and M in all three strips but presumably the exposures differ The order in which you made the exposures were as you have stated so it went from "worst" to nearly OK ( the more grey floor) then back to "worse again" What were the three exposures, just as a matter of interest?

I also take it that they were all developed one after the other i.e. within minutes of each other. If I have described everything that happened accurately then as far as I can see what appears to have happened has no reason to happen.

I cannot say what a large change in bulb illumination during the test strips might be able to do such as change the colour balance but I'd have thought that such a change in illumination would have been seen by you.

It is almost as if the dichroic filters were at the worst setting i.e. the setting you chose just prior to the first exposure then by themselves moved to the best then slipped again but not quite back to the worse setting that you had made I take it that you have a dichroic head. If you used a filter tray then the filters cannot move so as unlikely as my previous scenario is, it then becomes impossible

I just don't have an explanation that can reconcile the problems with the procedure you describe

If it is a dichroic head then all I can suggest is that you examine the M and Y dials by zeroing all 3 then moving each in turn from 0 to max checking if each changes as you increase the setting. Then choose any setting or better still the setting you used and switch the enlarger on and off three times checking each time if colour cast changes by itself

I hope that others here can come up with suggestions about the cause that explains what you experienced. Frankly I am now out of ideas

pentaxuser

Sorry, I'll do my best to address these points.

All three exposures were made with the same filtration, f stop and time. I was trying to test if I was getting any consistency. They should be exactly identical if everything was working correctly.

They were developed within hours of each other, in drums and from a fresh batch of chemicals that has been well replenished. The chemicals are stored in a 500ml bottle with all air excluded between processes.

I made the top one first, I was confused by it as it shouldn't have been red. I then made the middle one after making no changes and it went back to somewhat normal. Just to double check I thought I'd make a third and see what I would get and then it went back to red.

I just looked through my old test strips and I had something similar before I changed my old bulb. I took out my old bulb, cleaned the terminals, then when I put it back in my density went really poor. O took the bulb out and put it back in, density went up then without changing anything I'd get massive shifts of red between prints without reason or without changing anything. I then changed the bulb after that and it fixed the problem. This was only a few months ago so that's why I'm thinking the bulb holder could be the problem.

Bumba - You're within driving distance of Secondhand Darkroom Supplies in Oxfordshire. Maybe these frustrations you're having are frequent enough to consider buying a new enlarger:

https://www.secondhanddarkroom.co.uk/product/durst-370-colour-enlarger/

Ahh I'd rather fix the problem if I could but it would probably be wiser to get a new one. Do you think I could detect a problem with a multimeter?

 

[pentaxuser]

Bumba, it might be worth trying a quick clean of the current holder before buying a new one. Even if it doesn't cure the problem but only improves things then at least you will have a good indication that the problem lies with the holder which makes buying a new one less of a lottery.

I have had illumination fluctuations but I changed both bulb and holder together so can't say what each contributed to the fluctuations which were clearly noticeable to me but I don't recall it altering the colour cast. That's the bit I find puzzling and why I still wonder about whether a change in the holder holds the solution but I just can't think of anything else.

As long as you are electrically inclined a multi- meter may tell you something but a friendly electrician with diagnostic skills might also be worthwhile

pentaxuser

 

[Bumba]

Bumba, it might be worth trying a quick clean of the current holder before buying a new one. Even if it doesn't cure the problem but only improves things then at least you will have a good indication that the problem lies with the holder which makes buying a new one less of a lottery.

I have had illumination fluctuations but I changed both bulb and holder together so can't say what each contributed to the fluctuations which were clearly noticeable to me but I don't recall it altering the colour cast. That's the bit I find puzzling and why I still wonder about whether a change in the holder holds the solution but I just can't think of anything else.

As long as you are electrically inclined a multi- meter may tell you something but a friendly electrician with diagnostic skills might also be worthwhile

pentaxuser

I left it over the weekend and a few days in order to save my sanity. Couldn't even look at my enlarger. Today I thought I'd tackle it so I cleaned out my bulb holder vigorously with a small screwdriver and the resulting test strip looks very nice now. Hopefully that was what was causing the issue. I think I'll replace it as it's a cheap part and the current one is the original.

Thanks for the help everyone

 

[pentaxuser]

I left it over the weekend and a few days in order to save my sanity. Couldn't even look at my enlarger. Today I thought I'd tackle it so I cleaned out my bulb holder vigorously with a small screwdriver and the resulting test strip looks very nice now. Hopefully that was what was causing the issue. I think I'll replace it as it's a cheap part and the current one is the original.

Thanks for the help everyone

Glad the clean-out has worked. The way things are going in terms of enlarger parts I'd be tempted to buy a couple of new ceramic holders if there is any chance that the holder is unique to enlargers or even worse unique to Durst enlargers

I have only one spare myself and I am beginning to wonder if I should buy a couple more. As I understand matters the problem is caused by arcing inside the holder and that arcing is a way of life so it starts again from day one of a new holder

pentaxuser

 

[Kino]

If you do buy a spare, you should store it in a sealed bag with silica gel or other moisture absorbing media and keep them outside of the darkroom environment to avoid corrosion.

 

[Bumba]

I'm picking up a new holder tomorrow but does anyone have any tips on how to connect it? The old one connects to a small junction box. Do I need to crank down the screws when I wire the new one? Also do the wires need to connect physically to the mains wires or does the junction box handle that?

Thanks

 

[Mainecoonmaniac]

Are you keeping the chemistry chems stable?

 

[Bumba]

Sorry I'm back. It turned out to be the bulb holder. I changed that and it was a big help. Now I'm having a bulb problem and it definitely to do with the bulb.

If I reposition the bulb in any way the colour shifts (new and old bulbs have the same problem). I just put in a new bulb and tried it one way and it was too red so o flipped it round and now it's too green so I don't know which way is the best way to have it. It definitely seems like a red-green shift instead of a red-cyan or green-magenta shift.

Any ideas

 

[Kino]

Do you have the manual?

https://www.davidutrilla.com/cajon/durst_M_370.pdf

See page 8 about centering the lamp.

 

[Bumba]

Hey Kino thanks for the reply. My enlarger has a colour head so the lamp is centred automatically by some retaining clips so I'm not sure if it's down to that

 

[pentaxuser]

Hey Kino thanks for the reply. My enlarger has a colour head so the lamp is centred automatically by some retaining clips so I'm not sure if it's down to that

It sounds as if the 307 has the same set-up for the bulb as the M 605 which I have and if so there is only one position for the bulb but you have to ensure that both retaining clips are holding the bulb otherwise it will be held OK in the sense of being secure but will be at an angle so the beam isn't completely straight but I cannot see how this can change the colours

pentaxuser