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  1. #11

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    I've just seen the eBay link from Peter and the power connectors on the HP power supplies look very similar. I'll borrow a meter tonight and try and determine what power is on each pin. At $7 they could be the answer, even if you have to cut and splice the lead to get correct polarities. (Quite likely they will be the same).

  2. #12
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    Quote Originally Posted by tokam View Post
    I just pulled the plug from scanner to check polarity and its not going to be that simple. Canon, (Bless 'em!!!), have use a very proprietory looking three pin flat connector.
    See attached.

    Attachment 74956

    Attachment 74957
    Paper clips... very carefully.
    If the probes/leads on your meter are too big, get a bit of metal that will fit inside the holes on the connector. They will be nothing more than "pins" sticking out for you. Perhaps wrap electrical tape around them so you don't short anything. Do this before plugging it in to make sure you will not accidentally short any leads.

    Then touch the VOM's probes to the "pins" you made.
    Truzi

  3. #13

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    Another tip: you'll find you need three hands to do the voltage measurement. Get a hold of one of those hobbyist bench vises (any vise will work, but in the US, there's a brand called PANAVISE that's my favorite). Clamp the connector in the vise, pins pointing up. Plug in the AC cord and enjoy the (almost) effortless probing! :-)

    (profuse apologies for this being an electrical debug thread and not a film camera thread; though, hopefully, the strategy and techniques will be of interest to anyone repairing stuff)

  4. #14

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    yeah, i could see from the research that this was not going to be really straight forward. I have a brother in law who is very good with this stuff - sometimes..haha.
    Don`t worry about apologies for this becoming an electrical de bug thread on a film camera site, I posted the same in DPUG - no replies.All great info from everyone, well done and cheers

  5. #15

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    OK, I've located a cheap meter, probably only good for continuity checking but it gives me the polarity. Also found my vise, last used when I replaced two caps on the power board of a Samsung monitor last Christmas. The voltages per my meter are are low but from left to right on the attached picture are + gnd, -12V, -27V.

    Click image for larger version. 

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  6. #16

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    Well, *that* doesn't make much sense...seems like Mr. Murphy has stepped in to make life interesting.
    Thank you, tokam, for making those measurements!

    Someone in the Flickr conversation says he took the scanner apart and claims the center pin is GND.
    But I'm at a loss to figure out how that matches up with the voltages you measured.

    A possible next step would be to take the scanner apart and try to understand the circuitry connected
    to the pins, and figure out what voltages it wants to see. That's possible, and I have done it, but it
    takes a lot of experience and not a small bit of luck.

    Another possibility is to measure the voltages with the scanner connected and powered on.
    Often, these switching supplies do not regulate their outputs well until a load is connected.
    Again, this is a probably an exercise for "advanced students".

    I believe this scanner has an LED light source. These are sometimes powered by current-regulated
    supplies, and this could be the purpose of the third pin. If this is the case, you would not see a
    stable voltage on that pin, it would be whatever voltage is necessary to get the specified current
    to flow through the LEDs. We just don't know if this is the case.


    It may be that this is beyond us. It's probably a good thing that Craig has purchased another scanner :-)
    I'm sorry I couldn't have been more help. I can promise you that if I ever run across one of these scanners,
    I will have an irresistable desire to disassemble it, and post my findings on the web somewhere!

  7. #17

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    thank you all.Yes, it seems canon really made this one as difficult as possible.Probably beyond my capabilities so fortunate that i had another scanner available.I will put this particular project aside in the hope that perhaps a solution is found or i come across someone local that likes a challenge.Thank you all for your input and excellent clear replies - all much easier understood and clearer than the flickr info.Peter, i guess you will be on the lookout for one of these scanners, just so you can solve the problem:

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