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Thread: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

  1. #1

    Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    The other day I tried to use my Bessler 45S enlarger and the cooling fan did not come on. Is there a fuse, or does this mean I need a new fan, or motor. If anyone has a link to a manual it wold be greatly appreciated.

  2. #2
    John Olsen
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    Re: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    Does the light come on? There's a safety switch on the top access door that should cut power to everything if the door is not closed tightly. If the light comes on, then your fan must be dead or the wire to it is disconnected. If neither fan nor light come on, then either the door is not secure, the safety switch is broken, or the main power switch on the front is broken. The safety switch is under the top access door at the 11 o'clock position with respect to the light mixing chamber. Apparently, there is no fuse.

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    Re: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    When I picked up my 45S and first tried it out I noticed how quite the fan was. On a closer look the rubber mounts on the fan had rotted away, the fan dropped and the blades jammed against the housing. Link to Manual here

    George

  4. #4
    John Olsen
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    Re: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    That's an interesting failure mode. Thanks for sharing it.

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    Re: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    Interesting timing. I was just searching for Dichro 45S fan fuse and found this thread. I bought a Dichro 45S head on ebay, and it was delivered today. I just plugged it in (both cords), and my fan doesn't work either. The light comes on, but the fan does not.

    If I open the top door, put my hand on the top panel where the door switch is, and turn on the power, I can feel a slight vibration and hear a barely audible sound. But the fan remains still.

  6. #6

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    Re: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    I see what's wrong with my fan. The bracket that holds the fan vertically in the shroud came loose or maybe some part is missing, and it allowed the fan to shift backward and the blades to contact the metal shroud. One plastic fan blade is broken off completely at the hub and is lying at the bottom of the head beside the power supply board. Another fan blade is half missing, but I don't see where it went.

    If I push the fan bracket forward so the fan blades are not touching the shroud, then the fan works. Of course, missing one and a half blades, it's unbalanced and shudders. I believe the whole fan assembly will need to be replaced, although it is possible that I might be able to replace just the fan rotor, and fix or brace the fan bracket so the blades are positioned correctly in the shroud.

  7. #7
    John Olsen
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    Re: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    Skip: Replace the whole fan. I think the vibrations of an out-of-balance fan will vibrate your film and hurt focusing. Who'd have thought this would be a popular thread?

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    Re: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    John, I think that's best too. The vibrations are quite heavy. I am planning to take the stock fan out altogether and replace it with a 110 volt axial cooling fan. I just have to find one that is not too loud, and then mount it with rubber vibration dampening mounts.

    Does anyone have any idea what CFM rating I'll need?

  9. #9
    8x10, 5x7, 4x5, et al Leigh's Avatar
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    Re: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    Fans come in pretty standard sizes. Hopefully when you take it out it will have a label with the voltage and cfm rating.
    Is this a "muffin" fan, being an integral impeller and rotor inside a flat square metal/plastic housing?

    Mouser Electronics at www.mouser.com should have a proper fan and the rubber grommets to use for mechanical isolation.
    They're great folks to deal with, no minimum order, and only actual shipping charges. I get all my electronic parts from them.

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  10. #10

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    Re: Bessler Dichro 45s enlarger-no cooling fan-Is there a fuse?

    The original fan is not in a housing. It is a naked fan that is mounted so that it fits within a shroud that is built-in to the head. The plastic fan rotor is attached to a shaft that protrudes from a motor that is mounted in a bracket that sits on top of a transformer, and the whole affair is attached to the inside base of the head with four rubber grommetted nuts on studs. I couldn't find anything like it at Mouser, but I didn't know how to narrow the search, and I didn't feel like browsing through 87 pages of fans.

    I replaced it with a 120VAC muffin fan such as you described. I mounted the fan housing on the built-in shroud with silicone grommets to dampen vibrations. I'm not sure if it's damped enough though. I can still feel some slight vibrations being transmitted to the enlarger at the film stage, so I'm going to have to take it out and try to isolate it better.

    There are some very good pictures of the original fan, motor, and transformer in this PDF document http://alexbondphoto.files.wordpress...beselermod.pdf which is from this site: http://alexbondblog.com/tag/darkroom/

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