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Thread: Circuit diagram needed for Durst power supplies EST 301 and EST 450

  1. #11
    8x10, 4x5, ..., Tessina
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    Re: Circuit diagram needed for Durst power supplies EST 301 and EST 450

    Quote Originally Posted by ic-racer View Post
    In fact I'm hard pressed to think of any condenser enlarger that came with a regulated supply. Did you have something in mind?
    I was thinking of real enlargers, not 1940's omegas with 212 photo bulbs. (I used one in the 1960s... what a pain!)

    I use a two-color Ilford Multigrade head, which has a separate 300w halogen lamp for each color. Each lamp has its own regulated supply, to maintain the ratio of colors to the VC grade set on the head, and normalize the intensity.

    All tri-color (CMY) heads that I've seen use regulated supplies. I've never used one of these.
    I did use an additive tri-color head when I was printing Cibachromes ~25 years ago.

    There were some early photobulb enlargers that used a Sorensen constant-voltage transformer in a box. To a casual observer it might look like a simple transformer. It did a good job of providing regulated power over a wide range of input voltages.

    As with any other step in the photographic process, powering the enlarger lamp(s) is one factor that can affect final product quality.

    I do have some experience with power supplies, having repaired many, and designed and currently manufacture one.

    - Leigh
    Last edited by Leigh; 3-May-2012 at 14:45.

  2. #12

    Join Date
    Mar 2010
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    2

    Re: Circuit diagram needed for Durst power supplies EST 301 and EST 450

    Meanwhile I substituted the capacitors in the EST 450 board, but something is still wrong, there's a resistor driving the colector of one transistor that literally burns. I will try to fix the problem (quite hard without the schematics). If I manage to track these problems I will post the solution. Anyway, I'm attaching pictures of the EST450 and EST301 regulator boards in case it's useful for someone else:

    EST 450:
    Click image for larger version. 

Name:	EST_450.jpg 
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Size:	58.7 KB 
ID:	73170

    EST 301:
    Click image for larger version. 

Name:	EST_301.jpg 
Views:	15 
Size:	60.1 KB 
ID:	73171

  3. #13

    Join Date
    Feb 2006
    Posts
    3,112

    Re: Circuit diagram needed for Durst power supplies EST 301 and EST 450

    Quote Originally Posted by jvelez View Post
    Meanwhile I substituted the capacitors in the EST 450 board, but something is still wrong, there's a resistor driving the colector of one transistor that literally burns. I will try to fix the problem (quite hard without the schematics). If I manage to track these problems I will post the solution. Anyway, I'm attaching pictures of the EST450 and EST301 regulator boards in case it's useful for someone else:

    EST 450:
    Click image for larger version. 

Name:	EST_450.jpg 
Views:	12 
Size:	58.7 KB 
ID:	73170

    Check that transistor. Check the base circuit of that transistor for correct bias.
    EST 301:
    Click image for larger version. 

Name:	EST_301.jpg 
Views:	15 
Size:	60.1 KB 
ID:	73171
    One man's Mede is another man's Persian.

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