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M3 has a Leica Meter MR4 now


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Well, almost now. It is being shipped to me next week.;)

 

What batteries will work in the MR4 meter? I know B&H has the Wein Cells but have also heard about using 675 hearing aid batteries.

 

Which ones do YOU use?:)

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Good choice Dave - the MR and MR4 are very nice on the M3 and M4. The MR4 has a top-mounted button for the metering switch, and it tends to side-load a plastic guide-pin for the contacts against a slot in the circuit board so that it wears on one side and lets the electrical contacts shift sideways, so that you may have to wiggle the button a bit to get good contact, if those parts are worn. If that happens, I've repaired them by building up the side of the slot in the circuit board with a coat of epoxy to restore reliable operation. The internal contacts also can tarnish, so learning to open it up and apply contact cleaner can also improve operation, if you find your unit is a bit flaky. But hopefully yours won't have these problems.

The Wein cells work well, but degrade with time whether used or not. They basically use a 675 hearing aid cell with metal added to make them the same size as a PX625. A cheaper alternative is to get a 675 adapter from Jon Goodman, who also sells camera light-seal kits - so a search can find his email address. He takes 625A batteries, removes the "guts" and makes them into adapters that take the 675 cell so they fit reliably. The 675 itself is both smaller diameter and thinner than the original PX625. Some people try shimming a 675 various ways, but the adapters are more reliable.

I've also used the CRIS adapter for 386 (1.55V Silver) cells, which use a diode to reduce the voltage. The CRIS adapters are more expensive than the Goodman/675 approach.

All of these work well in the meter, except that the center contact of these cells is smaller diameter than the contact on the original PX625, and the MR meters use a 3-prong contact spring that expects the original size. As a result you have to be careful fitting the battery. If it shifts a bit the meter may not work until you remove and refit the battery.

A 625A (1.5V) will fit better, and the internal meter pots can be adjusted to read correctly with it, but the voltage change as it ages isn't ideal.

The best fit and operation is still a PX625 mercury cell. I found one in a used camera that is still good! The PX625 (equivalent) mercury cell is still made in Russia, and for a while you could get them on eBay; but eBay de-listed the seller over questions of shipping "hazardous" goods; even though you can sell fluorescent bulbs with more mercury in them than in the batteries. Oh well.

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To illustrate the difference in center contact size, here's a CRIS adapter with a 386 cell, an old PX625 mercury cell (still works) and an equivalent cell from Russia, still made today- but unavailable most places. You can see why the adapter with smaller cell may not make contact in the same way as a real PX625.

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Tom, I have been looking around for Jon's email address but it must have been deleted some time ago.

 

Any assistance would be greatly appreciated so I can call him!:)

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Here you can see why using the battery adapters in the MR meters is touchy, even though the voltage is right and the outside dimensions are good. Compare this picture of the "center" contacts in the MR-4 with the pictures of the batteries above. Notice the contacts in the MR-4 form a "Y" shape and the ends of the "Y" where it makes contact are very close to the outer diameter of the center contact in the 386 cell that is used in the CRIS adapter. If the battery shifts to the side a bit, one of the contacts may hit the outer edge of the 386 cell instead of the center contact, shorting out the battery.

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I don't recall if the 675 cell is larger than the 386, but if you put the battery&adapter in the meter and the battery check looks "dead" try removing and repositioning the battery a bit. And if it stops working in use, try the same thing.

It may be a good idea to remove the battery when not using the meter, so that a knock doesn't move the battery and short and drain it.

I've had some 386 cells go bad quickly in the MR4, and suspect this is the reason.

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Hi, Tom...:)

 

Crazy, weird...got the first meter this week...it had a battery in it and no battery compartment cover. The battery is a Vinnic something or other, .1.5v I think. Anyway, it fits well and I put a velcro sticky over it and after cleaning the outside of the meter and getting it looking pretty nice, I spent all afternoon yesterday checking the reading of the meter with the X1...darned it didn't match 100% of the time!

 

So, now I have a metered M3! Jon's adaptor should be here tomorrow and I already have a bunch of the hearing aid batteries (1.4v)! I am thinking that the other meter, supposedly in mint condition, will be here by Friday. No idea if it works or not.

 

This is a really nice accessory for the M3 and with the hand grip I just received from a friend, I am having a lot of fun!:) Thanks in a large part to your tips, Tom!

 

I wish I could find a battery compartment cover for the black one, though.

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Dave - mailed you a cover from a junked meter. To install, remove the foot that fits the camera shoe (3 larger screws) and the cover fits over the brass bushing in the body for that corner. The two smaller screws on the foot adjust the clearance over the camera body, to keep it from rubbing on the top. If needed, loosen the large screws and adjust the small ones before tightening the large ones again.

Enjoy your meters - they are a nice addition to the M3 / M4 cameras.

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Wow! Thank you so much, Tom...you are a gem!

 

There is one large screw (the one for the battery compartment pivot) that is missing. This is too cool...

 

The instructions for adjusting with small and large screws is something I would never have found without your help!!!

 

I am really loving these meters!:D

 

Thanks again, Tom...I owe ya one, my friend.:)

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Not to take away from the OP's post but has anyone tried the Voigtlander VC II meter on the M3?

I have - and it works well; but I prefer the MR because of the way if couples to the shutter speed dial - and gives an easier to use dial for speed as well. I use my VC II on my IIIf.

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Tom, this has fixed my battery problem...adaptor from Jon, battery from the local pharmacy, and the battery cover + screw from you and we are good to go! I really enjoy using that meter and it will easily simplify my life as well as fix my keeper ratio problem!

 

Thanks so much.

 

Anyone else needing a meter should really consider an MR4! I think I will get one for my TLR! They are dead accurate when compared with the X1's meter.:)

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  • 6 years later...

Hi everyone, found this old thread on the leicameters. 
i bought an MR a few days ago. Looked pretty mint, but when i tried it (with still good old mercury battery), i got no reading at all. 
after disassembling the unit and cleaning everything with rubbing alcohol, it worked - somehow. 
the battery test showed a positive result, the needle stops in the centre of the spot. All good. 
when taking some light readings and comparing it to my handheld meter, i get some odd results. 
seems the leicameter meters at least 3 stops more light than my other meters. 
anyone an idea how it can be that off?

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Hello Martin,

Welcome to the Forum.

Perhaps we can solve this.

I think that the circuit for the battery test is a separate circuit from the circuit that actually measures the light. 

So, if the battery test goes to the correct position but the reading is not appropriate. You know that the battery is OK & that the battery test circuit is OK.

Since you get a different reading of the scene that you are measuring & it is always 3 stops off: This gives us a place to begin from.

When you replaced the parts that sat on the square in the center: Did you make sure that the pieces were fitted to their appropriate quarter, etc?

By the way, the materials that the meter is made of are not that robust. Please remember to only tighten the screws, etc to the point where they are "snug" & NOT overly tight.

Best Regards,

Michael

Edited by Michael Geschlecht
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Do you use the correct battery? MR might be rebuild for 1,5 V already by adding the diode directly on printed circuit board, then using Weincell or adapter reducing the voltage will lead to wrong measurement. There are 2 variable resistors there, they may be set in the way, that the battery test will shows proper results but measurement not. But most probably the problem is with corroded contacts, this this a weak point of MRs. I mean contacts on printed circuit board and the 2 sliders, one is for battery test, second for measurement. The circuitry used in test and measurement is almost the same, in test the CDs cell is detached and fix resistor is connected, the rest is the same

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Thanks for your fast answers! 
I reassembled everything correctly, i think. 
When the black mark on the wheel is facing  right, the meter is set to bulb. 
i tried a 1,5v battery too, but not much difference. 
i noticed that the needle will go to the correct zero-position without battery. 
when a battery is installed and i meter while covering the viewfinder, the needle goes up to about the middle of the range. 
shouldn‘t it be on zero then, too?

Maybe i managed to clean the test circuit, but didn’t quite make it with the metering circuit..

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Update: after opening and cleaning the circuit board again very softly with a bit of rubbing alcohol, the battery test is dead and there is no reading. Just like i received the unit. The battery housing looks a bit corroded too, maybe a minor battery leak some years ago. I didn’t touch any wires and was really very gentle, but something might have broken, although i couldn’t find where. 
So maybe i‘ll have to get it repaired by someone who likes soldering and knows which cables and resistors have to be working. 
Do you have any recommendations who i might contact in Germany? Is it worth the repair cost?

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