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'm glad I didn't go with a Beseler conversion.
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.info/forum/attachment.php?attachmentid=9772&d=1202449116 ).
Good find!
Wow, that really was a great deal! You got spare boards! (drool...drool) My L1840 was the exact same price.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.
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
...Do the specs drift off, or does it just go 'poof'? It does seem to be working fine right now.
If the chip is in the middle hours, I'd leave it alone and chances are you'll never need to replace it.
Dave
Louie,
Now I get what you were saying. I like that setup with the enlarger and cabinets on either side.
Nice and clean. Did you make your own drying cabinet? Forced air?
After forty-two years and at least six darkrooms built and equipped, the last five of which have been work-based, number seven (possibly the last?) is purely for my own indulgence and right in my own back yard.
So far it's working well, the only drawback being finding the time to use it without appearing to be a complete recluse and totally neglecting the rest of the household!
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