Durst L1840 Enlarger 8x10 10x10--Everything you wanted to know...

This thread is intended to document my restoration of a Durst L1840 and also to serve as a collecting ground for information on these enlargers. Those of you that own these enlargers, please feel free to contribute pictures of your enlargers and share your experiences with the care and feeding of this beast.

If anything, I hope it will at least provide some entertaining reading.

So, the first thing is to find a little home for the Durst somewhere in the darkroom. Just by chance my choosen spot is right under the 220 feed to my wife's Oven in the Kitchen. In fact, a new oven was just installed last week (so, Daddy also gets a new 'appliance'; thus the wife's OK for the enlarger....)

The new oven draws 30A and the enlarger draws about 7A (1500W/220V). The line to the oven is protected by a 50A breaker, so I will be able to use that same circuit for both the enlarger and the oven.

I have some pictures of the enlarger as it was found. It was purchased new in 1988 with the Aristo cold light head and a 300mm Rodenstock lens for almost $20,000. It was used make full sized lith enlargements used in screen printing large banners. It looked like it had spend most of its life in the horizontal position. It had been used on a track and projected onto a wall.

Both motors, the ECU and the coldlight seemed to function correctly.

I was not too happy with the way the coldlight was attached to the enlarger, though, it did seem that was the way the enlarger was delivered back in 1988.

There is a thick plastic plate that looks home made into which sheet metal screws are used to hold the coldlight. The connection was wrapped in black tape and this covered, and defeated, the heads built in filter drawer.

The enlarger was hard-wired right into the building's power grid, so I needed to cut the power to the room where the enlarger resided, and use a flashlight to remove those handy boxes on the back of the enlarger column.

My original intention was to use an enclosed car trailer for transport. It turns out that the vehicle that hauls the trailer was a Suburban. After some measuring, we thought the enlarger would just fit in the back of the Suburban, thus eliminating the need for the car trailer.

The enlarger was stripped as much as possible and loaded into the Suburban. One thing we could not get around was the need to have the enlarger's weight on the black knob on the side of the camera. I could not see an easy way to remove this knob, so we just padded things well and hoped for the best.

It turns out there was no damage to the knob.

These pictures are from the unloading process. I was too busy to take pictures while stripping the enlarger and loading it.

If not for the assistance of my brother (who did most of the lifting) this project would have never happened. He was also patient, because I was contunually slowing things down to make shure nothing got bent, scratched or broken during the transport.

Using the dolly did not help as much as one would think because most of the weight was centered over the camera (mid-column), rather than the base. The base is, in fact, aluminum.

Once I got the enlarger safely in the darkroom the cleanup process started. It seems that some of the paint on the base was permanently damaged by one of the process chemicals. Perhaps acetic acid? The good news was that most of the other chemicals (fixer and dev.) came off quite easily.

The ECU also cleaned up well.

The power supply had a rattle, so I opened it up to check things out. All looked good, excpet this little screw which holds the wires on the on-off switch, had come loose.

After cleaning I was able to do a mechanical assessment. So here is the to-do list:

Remove the plastic adapter and paint it so it does not look home made
Re-mount the cold light using black foam rubber, so the black tape is not needed, and so the filter drawer is functional.
Re-do the very cheap looking angle brackets holding the coldlight to the adapter.
Take the trim off the column and remove the 3 cosmetic bellows on the column. After having built a bellows from scratch, I think I know how to fix up these bellows.
Look into some matching touch up paint from the auto parts store

For power I wound up running a separate 20A 240v line with 12 gauge wire. The socket for this line is about the same size as a standard 120 socket but the slots are horizontal instead of vertical. Those large 50A 240 sockets for appliances that take 8 gauge wire are not the correct item.

After firing it up I realized the slow focus was not working. (In some dry runs, this was actually not a problem as focusing with the fast speed was fine but I like to have everything working correctly) So, I set out to see if I could fix it. I followed the diagnostics in the repair manual and traced the slow signal deep into the 24v motor control circuit board.

I came to the Quad Op-amp and there are some very strange readings, making me think that this 45 cent part is the culprit. One output pin it is supposed to read low voltage when a 13volt signal is mixed with a 15 volt signal at the inverted input. Seems the output pin is reading 33 volts which is not the correct answer for this logic circuit. This high voltage is keeping the motor pulse counting chip in reset mode and basically freezing the circuit. At least that is what I think. I will replace the OP amp and see what happens.