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  1. #11
    Steve Smith's Avatar
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    When experimenting with various cells in a Spotmatic, be aware that what appears to be the cortrect way round may in fact be upside down. It will not do any damage to the meter but a reversed cell will translate to reversed movement of the meter needle.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  2. #12
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    I bought a modern alkaline battery for a Spotmatic and at first it didn't seem to work, but the problem was that the original battery had a plastic insulator around it that prevented certain parts of it from touching the contacts. I wrapped a thin piece of masking tape around it and it worked fine then. So, if a battery fits, but still doesn't work, this is probably your problem.

  3. #13

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    Quote Originally Posted by Anscojohn View Post
    I found this on another website. I did not know this. And I have a Spot II and did not know this.

    Quote on:
    Availability of batteries for the Spotmatic is better than other cameras of the era because the Asahi engineers built in a bridge circuit in the metering which makes it battery voltage independent. This means you can use the original 1.35 mercury PX400 battery, or a 1.5V silver-oxide replacement without problems. An exact fit PX400S is available, or you can use a #392 cell with a small rubber-O ring (purchasable at any fine home repair center or DIY store) as a spacer. I believe a #397 also fits as well.
    Quote off

    My closest fine home repair center - Home Depot - used to have a display with about 3-4 dozen different size O-rings. Unfortunately, no more O-ring selection. All the more reason to visit your fine local hardware store.
    "Far more critical than what we know or do not know is what we do not want to know." - Eric Hoffer

  4. #14

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    I've used this source for hard-to-find mercury cell replacement batteries for the Spotmatic and others: http://www.myoldcamera.com/

  5. #15
    CGW
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    The not-so-hard-to-find but pricey Wein cells are zinc-air batteries. There are close fits among much cheaper hearing aid batteries for Pentax and other merc cell bodies.Alkalines will work with Spotmatics but be aware that they don't have the old merc cells' near-flat discharge curve. Tons of info on photo.net about merc cell replacement solutions. Just enter "PX625" or PX400" in the search box.

  6. #16
    Steve Smith's Avatar
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    Quote Originally Posted by CGW View Post
    Alkalines will work with Spotmatics but be aware that they don't have the old merc cells' near-flat discharge curve.
    But as it has a bridge circuit it doesn't really matter.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  7. #17
    CGW
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    Uh, it will when the cell's dying, dropping voltage, and giving "off" meter readings. Merc cells ran strong and just died, rather than fade. Zinc-air cells probably come closest to that if you're enough of a survivalist to futz with O rings and other hacks to keep an oldie working.
    Last edited by CGW; 06-21-2010 at 07:00 PM. Click to view previous post history.

  8. #18
    Steve Smith's Avatar
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    Quote Originally Posted by CGW View Post
    Uh, it will when the cell's dying, dropping voltage, and giving "off" meter readings.
    As long as it has enough power to move the needle one way or the other when over or under exposing then the correct exposure will be indicated correctly.

    The Spotmatic's bridge circuit shows correct exposure when the same current flows in each side of the circuit. The meter shows the difference in voltage between the two middle points of the bridge and at correct exposure no current flows through the meter so the needle rests at its centre point. X - Y = 0 when X = Y. The actual value of X and Y is irrelevant.

    So this circuit will work well with mercury, alkaline and silver cells. You could even wire up a couple of potatoes with iron and copper nails as conductors if you wanted to!


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  9. #19
    CGW
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    Guess it's why I retired my old Spots and Minoltas since the difference between a working meter and an accurate became evident. Some proved linear but off +/-. while others were erratic and undependable--neither being surprising for 40+ year-old cameras.

  10. #20
    Steve Smith's Avatar
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    Minoltas like the SRT series definitely need a good 1.35v source. Using a silver oxide cell with a schottky diode wired in series with the battery is a common modification.

    If you are using a 1.5v cell on a bridge circuit camera like the Spotmatic, although it will be accurate at normal exposure, the needle will go to a different point if it's under or over exposed so if you had a point to which you always set it e.g. for two stops extra exposure for a backlit scene, you will need to re-learn its over expose position.

    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

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