Trying to make a zinc air 675 batt work for a Minolta SRT201 inst of mercury batt

Kruger

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Hi everyone. I'm trying to make my srt201 work with a zinc air cell 675 instead of the original 625px mercury batt that is now banned. It came with one but it died this morning ! Just at the beginning of a back packing trip in Rajasthan India. I found a zinc air battery that is one of the alternatives. But the needles still moves to the box when I choose BC instead of "on", which is is the battery check. Also the light metering seems weird compared to what I had before. I tried with a guy to take off the sticker in the cap and put carton paper around the batt to make it hold more or less in place (aaah India). But it seems it doesn't work. People recommend a #9 washer but here in Udaipur I couldn't find one.

Any tips or help would be greatly appreciated ! Thanks !
 

E. von Hoegh

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See if you can find an O-ring to act as a bushing, to hold the battery centered in the compartment. An alternative would be to fing some copper wire that you can make into a hoop to go around the cell, holding it centered. You'll need wire about 3/32nd in/ 1.5mm in diameter.

Edit - make certain the contacts in the battery compartment are clean - the cell that "died' abruptly may not be dead.
Also, the 675 is a wee bit thinner than a 625 - a small washer or a pad of tinfoil might be the solution. Be careful not to short circuit the cell, put any washer or pad on the positive side away fron the negative terminal and the tiny gap between it and the shell (positive).

Be advised that Wien cells do not last long. Neither will the 675 hearing aid cells unless you block off 3 of the four airholes. You can block the holes with a tiny dab of glue.
 
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Gerald C Koch

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IIRC correctly the only difference between the Wein and a regular zinc-air hearing-aid battery is an additional hole to allow for more oxygen.

If your camera is not to be used for awhile remove the battery and cover the holes in it with a bit of black electrical tape to keep it fresh.
 

E. von Hoegh

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Wien cells have two holes, standard cells have four. You need only one for the intermittent and very light drain of a camera meter. I've got over two years on a cell with three of the four holes blocked. Two years last April, to be more precise.
 
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Kruger

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Hi guys ! Thanks for the help. Erin cells don't exist here and I'm backpacking so I can't order online. Right now my o-ring is made of carton paper from the packaging of the batteries. The cell moves a bit sides but just slightly it seems the center more or less remains on the negative side contact.

Also we removed the sticker that was on the cap, thinking it could help to make contact with the + since he diameter is smaller. Was that a bad idea ? Can it damage the camera or short circuit the cell ?

If I put a thin foil pad, should I put it on the top part of the cell where the plus is ? Without the sticker is it going to electrocute me or damage the camera ?

It's strange cause if I target bright light in clouds etc the needle goes to the bottom as it should according to the manual. And if I target dark corners it goes up. But I don't know why it keeps going to the box when I choose BC is it because its not the appropriate battery and just a "fix"? Thanks !
 
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Kruger

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Please if any one could help me figure out why the BC says its serviceable even though the metering seems to work. I didn't try a gray card and all but when I look at bright light or sun it goes down as it should etc. I also put a little 1mm or 2mm aluminum (thin foil) pad on the +side before closing the compartment. Didn't seem to make any changes. Thanks !
 

MattKing

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By "serviceable" do you mean "requires service"?

The zinc air cells supply the same voltage as the original mercury cells, so they should be capable of making the meter work properly, as well as making the battery check work properly.

So as long as you can make the physical size of the battery work the zinc air cell should suffice.
 
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Kruger

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Thanks for replying. Yes I'm quoting the manual I guess they meant it needs to be replaced. It's strange cause the arrow goes really down as it should when it's too bright and vice versa though. However I don't know if it is displaying expo accurately.
 

E. von Hoegh

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The battery check reads OK because the cell is the correct voltage, period. The circuitry does not know it's a makeshift as far as size goes. As for placement of a washer or pad, see my post above where I explain this. 1.5 volts cannot electrocute you!
 
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Kruger

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Thanks for your reply. When the needle is on the square it doesn't mean it's ok it means it needs to be replaced. That what they say in the manual.
When I mentioned electrocution I was more worried about a shock that could damage the camera.
 

E. von Hoegh

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E. von Hoegh

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Aha. Now I think it makes sense.
Kruger, "seviceable" means able to give service, useable, able to perform the task at hand - powering the camera's meter - or in other words, good.
I think you took it to mean something like "requiring service" as in maintenence, repair, replacement.
 

donkee

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I seem to have luck doing it the lazy way. I drop the hearing aid battery in and screw the cap on. Bingo! No adapters, O-rings, etc.

According to my Minolta autometer IVf the SRT cameras are dead on.

I did have a problem on one SRT where the battery cap will screw in so much it interferes with winding to the next frame. Backed it off a half turn and everything is working good.
 

Jon Goodman

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Or you could purchase the #675 adapter I've made for years and support an APUG member at the same time: http://rick_oleson.tripod.com/index-111.html (you can see it midway down on my friend Rick Oleson's page). Unlike the slip-on washer approach, mine will place the zinc-air cell at the proper height every time. It is still $14 and that includes free shipping to anywhere and a lifetime guarantee. A small 100% neoprene ring keeps the cell centered in the adapter and the design prevents any damage to your camera from a malfunction of the zinc-air cell. Also, unlike the adapter mentioned above, mine is guaranteed to be infinitely stackable (try to stack Wein cells or the battery adapter above...you'll discover the top cell will be intermittent at best and may not work at all).
Please email me at jon_goodman@yahoo.com if you're interested.
Jon
 

MattKing

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Jon's adapter works really well, and the #675 hearing aid batteries are incredibly inexpensive.

And the bonus? You get to deal with Jon.

Just a satisfied customer here.
 

donkee

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Jon, you have supplied me with seal kits for all my 35mm SLRs and Mamiya C220. Ssoon I'll be hitting you up for kits for my Bronica SQ backs> Might as well tack on a couple adapters too! The lazy way works but the right way is usually better.
 

gone

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As others have suggested, it's very simple to make a little 'O' ring for your battery w/ anything at hand. Wire, balled up tinfoil, pinched up paper or cardboard, a washer, etc. It need not be exact, just good enough to keep the battery from shifting.

When you get back home, save yourself a LOT of future grief by buying one of those cheap multi meters that accurately measure voltage. I bought mine eons ago for $5 and it has taken care of all the guess work. Now I know exactly what the voltage is of any battery at any time, an invaluable thing. Sometimes even new batteries are flat, so you need to know that if it occurs. Also, some cameras are real fussy about voltage, while others work fine w/ "close enough". For now, sunny 16.
 

Jon Goodman

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Thanks guys! You know I always appreciate the support for my various (two at this point) projects. Oh, plus the camera leather kits. I still have some of those left and I'm about to lower the price yet again.

About the multimeter, if you find one of the old style with a needle, it can be a good thing to have and at some point it will probably save you some money and allow you to perform some home repair magic. Those old meters are terrific for checking capacitors. You can tell in an instant if they're working or not. If your air or heating fan goes out or if a motor in your clothes dryer or washing machine stops working, it is a wise idea to check the capacitor first. The weakest link and the thing that will frequently cause an AC motor to stop working is either the start capacitor or the run capacitor. Many motors will only use a run capacitor. This is also one of the things that stops your airconditioning compressor from working, too. The start capacitor is like a large bucket of electricity that is fed in one quick dose to your compressor motor to make it start working. Think of it like a Drill Sergeant with big shoe that kicks your tail out of bed. The run capacitor keeps the magnetic fields rotating so the armature will spin. Rather than purchase a new motor or call a serviceman, you might have your motor working fine again with a new capacitor (which will generally cost you $10 or less for a run cap or between $20 and $100 for a start cap...depending on the type of application, voltage, etc). If anyone wants more of an explanation about this, please let me know.
Jon
 

mgb74

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I'm no expert, but I know that there are some tests that are better with an analog (needle) multimeter. For example, testing the transformers in halogen lighting.
 
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