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  1. #551
    ic-racer's Avatar
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    Quote Originally Posted by langedp View Post

    It turns out, they gave me all their spare parts for the durst as well. I have a complete set of spare electronics. My undergrad is in electrical engineering which came in handy to diagnose a few "issues" with the enlarger after I brought it home.

    Dave
    I got the sales brochure for the HL2501 in with the papers on my L1840. I saw the fancy circuit boards that swing out. At the time I was thinking "yeah, they know you are going to be down there on your hands and knees fiddling with that all the time..." because, I had just spent quite a few hours signal tracing and fixing the 24v motor speed control on my L1840's power supply (http://www.largeformatphotography.in...2&d=1202449116 ).

    Good find!

  2. #552
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    Quote Originally Posted by Curt View Post
    ... I'm glad I didn't go with a Beseler conversion.
    I agree. If you're going to enlarge 8x10 negs, get the most enlarger you can afford. You won't regret it. This is actually my third 8x10 enlarger. First was the Omega F. Then a DeVere 1010 horizontal. And now the Durst 2501. The Durst is by far the best designed and in the best condition.

    Dave

  3. #553
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    Quote Originally Posted by ic-racer View Post
    I got the sales brochure for the HL2501 in with the papers on my L1840. I saw the fancy circuit boards that swing out. At the time I was thinking "yeah, they know you are going to be down there on your hands and knees fiddling with that all the time..." because, I had just spent quite a few hours signal tracing and fixing the 24v motor speed control on my L1840's power supply (http://www.largeformatphotography.in...2&d=1202449116 ).

    Good find!
    Thanks. That's always a risk with these things. I had some display problems initially on the console so I pulled the 'scope out and checked a few things. Luckily I received a full set of schematics along with the spare parts. Turned out to be nothing more than dirty contacts on one of the ribbon cable connectors.

    Most of the electronics are rack mounted in the base on pull out slides. Pull up a stool and you're good to go. One of the key spare "parts" is a complete slide rack with all the boards and power supply.

    Dave

  4. #554
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    Quote Originally Posted by langedp View Post
    Thanks. That's always a risk with these things. I had some display problems initially on the console so I pulled the 'scope out and checked a few things. Luckily I received a full set of schematics along with the spare parts. Turned out to be nothing more than dirty contacts on one of the ribbon cable connectors.

    Most of the electronics are rack mounted in the base on pull out slides. Pull up a stool and you're good to go. One of the key spare "parts" is a complete slide rack with all the boards and power supply.

    Dave
    Wow, that really was a great deal! You got spare boards! (drool...drool) My L1840 was the exact same price.

    The L1840 only has two boards, and I would love to have had replacements. I did not get a schematic, my schematic is still 'on the way' from Durst.it, but I was able to scribble one down by following the traces.

    With your electrical background, you would be the only one to appreciate this, but Durst was using part of a NAND logic chip as a positive feedback loop to make an oscillating clock for the motor speed control. Just a resistor and capactor to regulate the speed of the oscillations. Well, either the input impedence of the NAND chip changed or the capacitor was leaking, but a new 40nf cap and a trimmer and I was set. With the trimmer I got it oscillating right at factory specs and now she focuses like a dream.

  5. #555
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    Quote Originally Posted by ic-racer View Post
    Wow, that really was a great deal! You got spare boards! (drool...drool) My L1840 was the exact same price.

    The L1840 only has two boards, and I would love to have had replacements. I did not get a schematic, my schematic is still 'on the way' from Durst.it, but I was able to scribble one down by following the traces.

    With your electrical background, you would be the only one to appreciate this, but Durst was using part of a NAND logic chip as a positive feedback loop to make an oscillating clock for the motor speed control. Just a resistor and capactor to regulate the speed of the oscillations. Well, either the input impedence of the NAND chip changed or the capacitor was leaking, but a new 40nf cap and a trimmer and I was set. With the trimmer I got it oscillating right at factory specs and now she focuses like a dream.

    I not only got spare boards, but I got a second entire system. See the photo below.

    I saw your other thread on rebuilding your 1840. The 4093 nand gate they used is not your normal nand gate. They made a gated oscillator with it which is not uncommon and is shown on the data sheet. A very inexpensive way to make a square wave oscillator that you can turn on and off.

    Dave
    Attached Thumbnails Attached Thumbnails DSC01033.jpg  

  6. #556
    ic-racer's Avatar
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    Quote Originally Posted by langedp View Post
    The 4093 nand gate they used is not your normal nand gate. They made a gated oscillator with it which is not uncommon and is shown on the data sheet. A very inexpensive way to make a square wave oscillator that you can turn on and off.

    Dave
    Yea, they are showing an "Astable Multivibrator" which is the same circuit. I missed that when looking over the sheet. I was just placing an order to Mouser.com for another project and wondered if there would be any benefit in putting in a new 4093? For, example, how do you think it fails? Do the specs drift off, or does it just go 'poof'? It does seem to be working fine right now.
    Last edited by ic-racer; 03-02-2008 at 11:38 AM. Click to view previous post history.

  7. #557
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    Quote Originally Posted by ic-racer View Post
    ...Do the specs drift off, or does it just go 'poof'? It does seem to be working fine right now.
    I'd leave it alone if it's working. Order another IC as a spare since you're placing an order anyways.

    IC reliability typically follows what's known as a bathtub curve. Failure rate vs. time plotted on a graph looks like the cross section of a bathtub. High failure rate in the intial hours known as infantile failure due to mfg defects. A long, low failure rate during the middle hours which could last many years. And a high failure rate again towards end of life. Thermal cycling from power on/off is one of the failure accelerators and soldering and desoldering the IC a number of times doesn't help. If the chip is in the middle hours, I'd leave it alone and chances are you'll never need to replace it.

    Dave

  8. #558
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    Quote Originally Posted by langedp View Post
    If the chip is in the middle hours, I'd leave it alone and chances are you'll never need to replace it.

    Dave
    Thats great to know, thanks!

  9. #559
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    It just occurred to me that I had made some pictures of my setup a while back but had never posted them. So here goes. From left to right:

    - the corner enlarger station with the Omega DII

    - the film drying cabinet

    - the ventilation system (with the fan OUTSIDE the darkroom)

    - the wet side. Print drying screens slide under the sink.

    - overall floor plan
    Attached Thumbnails Attached Thumbnails Enlarger small.jpg   Negative drying small.jpg   Ventillation small.jpg   Wet side small.jpg   Floor plan.jpg  

    Last edited by Monophoto; 03-06-2008 at 11:59 AM. Click to view previous post history.
    Louie

  10. #560
    pesphoto's Avatar
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    Louie,
    Now I get what you were saying. I like that setup with the enlarger and cabinets on either side.



 

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