Built in "Voltage Converter" in Leicameter MR4?

[Kumachrome]

I believe this was briefly covered on other posts, but I can't seem to find them. Anyway, I'm getting a Leicameter MR4 in the mail, and my research on it seems to be hinting that I don't really need to get a Weincell or battery voltage converter for it. I read something about the meters having some kind of "voltage converter," (apologies if my lack of technical knowledge is making any electrical engineers here bang their heads against wall.) Basically, this "converter" adjusts the flow of electricity depending on changes in voltage and such. Some people were saying all they had to do was make sure their meter was zeroed and even using 1.5v hearing aid batteries worked and gave accurate exposure readings.

I wanted to know if anyone here has any further information on this, or can confirm it. In your experience, is the meter accurate by using a 1.5v battery? Or did I maybe misunderstand what I read?

 

[shimokita]

From what I have read, the Leicameter MR4 requires a PX-625 replacement type battery (e.g. the following link).

http://leicaphilia.com/using-a-leica-mr4-meter/

As well a number of sites (such as B&H / Adorama) recommend the Wein EPX-625 (MRB625) to replace PX-625, PX-13 and MR-9. I use the MR-9 adapter when replacing mercury batteries (YMMV).

I understand the Wein EPX-625 is slightly different from the hearing aid battery... source being the internet...

 

[Robert Lai]

For the meters that I had overhauled by Gus Lazzari, I use the pratedthai battery adapter. Gus believes that trying to adjust the circuit for 1.5V will affect its linearity.
https://www.ebay.com/itm/MR-9-Batte...083632?hash=item1e6b1d0830:g:hkIAAOxykMpTHFbQ

I have others that Don Goldberg has fixed, and he adjusts them for a 1.5V cell. Don is not so concerned about linearity. In practice they both seem to work fine.

The old mercury batteries are quite corrosive. Many meters are dead due to corroded circuitry by a leaking battery.
The Wein cells are also very corrosive. If they die, remove them immediately.

Also, a lot of these meters died because owners didn't know how to open the battery door properly. You need to set the shutter dial into the 2-8 second range, then gently slide the door open. Otherwise, the pin on the shutter dial that links with the shutter dial on the camera will distort and break the battery door.