Awesome job! I bought an L1840 several years ago and intended to rehab it as well. It is still in storage, just needs a bellows and light source. It came with a vacuum easel and a massive 2 bladed thing whose name escapes me.
I wonder if I'll ever get to it or if I should pass it along...
I may be mistaken but I think I read somewhere that Camera Bellows in UK made the bellows for Durst enlargers.
http://www.camerabellows.com/Enlarger.html
Dear all,
my name is Claus, I am a b/w photographer living in Berlin, Germany, running my own darkroom to produce my prints. I am using a Laborator 1300 with CLS1000 which is an incredible piece of old school craftmenship, solid, reliable and precise. As far as I know the L1300 uses the same column as well as the same large power pack between the "legs" incl. the ECU1000 for adjusting head position, focus and time. Fortunately I found this forum and this thread and I wonder / hope if I can find any help/solutions here because I am not an electronic specialist.
I HAVE A SEVERE PROBLEM.
My problem is that the "focus up", operated by one of two buttons on the ECU1000 doesn't work properly anymore. Some weeks ago it started that the button sometimes failed to work for a few seconds or so. After a while the "focus up" worked properly again. This function is vital for using the L1300, that's why I am so concerned.
After having switched off the machine for 2 weeks I started working again yesterday and noticed that the "focus up" function did not work at all anymore. Luckyly after waiting for 30 minutes it came back into function again, but not reliable. The function failed again and again, sometimes for 1 second, sometimes for a minute or longer.
I must solve this problem!
Has someone of you experienced the same problem with the electronical stuff or does someone have an idea what could be wrong with my L1300 and can help me?
THANK YOU!
Claus
Laborator 1300 with CLS1000 and ECU1000
for clarification of the problem:
1. what happens at power up, does the focus motor:
remain in position?
goto minimal position?
goto maximum position?
make random movement?
2. same question when you hit the up button?
3. same question when you hit the down button?
4. is just one of the directions affected?
5, what happens if you push the buttons on the remote control?
I think I have heard that the pushbuttons on the ECU fail; if they are single pole
that can be easily checked with an Ohmmeter, or by shortening of the contacts.
I suspect that the movement is controlled by limitswitches at both ends;
could it be that these are activated by mistake?
Does gentle agitation of cables and connectors point to a bad contact?
The focussing circuitry is not very complex, and unless it is an intermittant
problem it should be easy to fix.
The focusing motor control is a pretty complex circuit. It took me a month to figure it out. Once you get past the digital multiplexer and de-multiplexer, there is a 'constant-speed' motor control which relies on a tuned oscillating circuit. On the 24v board in the power supply, IC3 (which is a quad op-amp) functions as this oscillator. No 'crystal control' here; two sections of the analog op amp are wired into a feed-forward loop with a capacitor and resistor that are tuned to oscillate at 600 cycles per second.
Based on the symptoms you report, this oscillating circuit would be the first place I would look.
On my enlarger that circuit was not oscillating at all, due to leakage of current through the PC board or through the capacitor, and thus the focus motor was non-functional. After replacing the leaky capacitor and cleaning the PC board, I got the clock circuit oscillating again and was up and running.
I have a PDF of the service manual (3 MB in size). PM me and I will pass it along.
I repaired mine without an oscilloscope, but if I were to do it again, I would get one. Everything is controlled with pulses and you need a scope to see what is going on.
What I did, without a scope, is to use my AC RMS voltmeter to 'guess' at what the waveforms might be as I was tracing the signal. I got lead down a lot of stray paths that way.
Dear George W, dear ic-racer,
thank you for your immediate answers.
@ George-W, here are the answers:
1. At power up nothing happens.
2. Sometimes focus up motor works, sometimes not. If it does not work then in neither case for slow or high speed. If it does work then it works for both speeds
3. Everyting o.k. slow and fast speed working perfectly
4. Yes, only focus up is affected
5. I do not have a remote control
Activation of limitswitches is thinkable, I did not open the chassis yet, because I don't know which screws to unscrew. There are two visible limitswitches who prevent the lensboard from hitting the baseboard and they seem to be o.k.
Gentle agitation has not been tested yet, I will do so.
@ ic-racer:
I'll send you a PM and am looking forward to your service manual. Where is the control cicuit lockated, in the ECU1000 or in the power pack on the floor and is it easy to find? Is the control circuit a printed board, which can be changed as a whole? And, if yes, do you know, where to find this spare part?
And, if the oscillating circiut would be o.k., what would be your second idea what to check next? It looks as if you do not see a malefunction of the up-button.
I am asking because I need to find someone in Berlin who can fix that problem for me and it would be extremely useful to feed him with as much expert knowledge as possible.
Regards
Claus
@Claus,
Thank you for the information.
If you do not have the measuring equipment and the troubleshooting experience,
the problemsolving will not be so straight forward. Ideally you would locate from
the schematics the oscillator IC, and hook up an oscilloscope, and proceed from there.
Very interesting is the point that *only* up movement is concerned. That rules out
at first sight all components that are common for both directions, as powerdrive and
possibly oscillator.
It would leave at first sight:
1. up pushbuttons and related cabling (easily checked with a multimeter)
2. upward limit switches (if temporarily up movement works, you can hit them to check that
they interrupt movement; that does not rule them out however)
3. all possible relays that switch between up and down movement
4. all connectors and cables making intermittant contact (if up movement is temporarily
working, do gentle cable agitation, to see if this stops the movement)
Other hint to the cause is that *both* fast and slow "up" pushbuttons are affected.
That might point somewhere where the setpoint for the power amplifier is generated;
that depends on the way the direction change is done, (either by a relay at the output
of the powerbox, or electronically in the vincinity of the oscillator).
Claus, did you get my email?
The motor speed control is in the box on the floor.Originally Posted by urs100
I have heard that Durst USA can get a new or re-manufactured board, but it might be expensive.Is the control circuit a printed board, which can be changed as a whole? And, if yes, do you know, where to find this spare part?
And, if the oscillating circiut would be o.k., what would be your second idea what to check next? It looks as if you do not see a malefunction of the up-button.
Like George posted, you need to start at the switch and follow the signal into the logic matrix of the board in the control unit. From there the signal will go to the main board in the power supply box on the floor. From that main board, the signal gets to the the "24V" motor control board (which is easily removed and replaced with a plug-in connector). The signals from that "24V" motor control board feed the motor with the appropriate pulsed current. All the 'logic' for the limiter switches is also handled on the "24V" board.
I'll get the pdf file out to you.
I am asking because I need to find someone in Berlin who can fix that problem for me and it would be extremely useful to feed him with as much expert knowledge as possible.
Regards
Claus
Also, resummerfield (who has a 1840 and from whom I got the schematic) was able to easily fix his motor control problems at the switch level. He is on these forums, maybe he will chime in if he has anything to add.
This is part of a PM from resummerfield.
My enlarger came with a remote control that plugs into the ECU1000. It is a little keypad that sits on the baseboard and has the 4 buttons just like the ECU1000; press a button gently for slow speed, and press the button further and the motor goes to high speed. Just like the ECU1000. When I tried the remote, the focus motor (I don’t remember which direction) only went at high speed. I disassembled the remote and found the internal switch mechanism was plastic, and had thin plastic “pins” to align the switch contacts. One pin had broken. I removed all the pins (there were 4, one for each switch), and substituted a similar metal pin by drilling the case for the slightly larger pin. I used a brazing rod, but I can’t remember the size. That was about 3 years ago, and it has worked perfectly ever since. So I would check the ECU1000 first. Be very careful when you open the ECU1000, because if anything is broken inside, the switches may come apart. Don’t lose any parts!
This picture is from earlier in this thread. The power supply board comes out easily and could be replaced in 5 minutes. The time and hard work will be in determining if the board is the problemThe 24V board has been taken out in the picture and is at the top of the picture.
Again, from earlier in the thread. This diagram shows how everything is based on the pulses from the clock circuit at the top of the diagram. The slow-speed is pulsed and during the 'off' pulses, the system charges a capacitor (C5) with the back-EMF from the free spinning motor. The discharge time of that capacitor (C5) determines when the next pulse occurs.
The end result of this is that the motor will move the same speed moving the lensboard up as down. Without a circuit like this, the motor would run faster going down than up.
The complexity of this 'constant speed' circuit, though, makes troubleshooting much more involved than a simple 'on-off' motor control circuit.
http://www.largeformatphotography.in...4&d=1203368279
Posting Permissions
Reply With Quote
Bookmarks