[alanablues]

Hi there everyone,

I recently purchased a Pentax Spotmatic. The battery cover was corroded and very difficult to open but I eventually opened it and cleaned it out!

There was a battery inside that appeared to fit marked "400 +". Now I am unsure what to put in there instead.

I have read some things about small rubber rings, and other things about whether to use mercury or silver oxide. How do I obtain these rubber rings? And what battery should I purchase? Does anyone use a battery that fits without the rubber ring?

Also- how do I verify if the lightmeter works? I tried to use a hearing aid battery wrapped in foil to match the size of the previous battery, but when I loaded the film and played around with the exposure, the lightmeter did not move. So I suppose it isn't working, or I haven't figured out how to turn the lightmeter on.

Thank you so much - very excited to use the camera.

[caferacer73]

My Spotmatic II take a 394 battery, which is a silver oxide mixture (better voltage regulation). This was the replacement recommended in this forum since the original mercury battery is no longer available (banned since the 80's). Hope this helps.

[longbow]

These fit perfect: amazon.com: Energizer 387S Button Cell Silver Oxide Watch Battery Pack of 5 Batteries: Health & Personal Care?tag=pentaxforums-20&

[Ontarian50]

One thing to remember when adapting batteries to the Spotmatic, is that the battery compartment in the Spotmatic is "upside down" to what you might expect.

The battery cover is marked with a fine " - " for the negative contact of the battery, which means the positive side has to go into the compartment recess and make good contact with that small terminal inside. This is why the battery needs to be so small, and why you need some kind of gasket around it to keep it aligned. Original batteries had a wide metal flange attached to them. Later batteries made to fit the Spotmatic had a plastic gasket surround, usually clear or blue coloured. The plastic gaskets can be pried off dead batteries and re-used with a new silver oxide battery that fits (usually that 394 size).

So, yes, if you put the battery into the compartment the direction it looks like it goes, you will have reversed polarity, and the meter won't work.

[alanablues]

One thing to remember when adapting batteries to the Spotmatic, is that the battery compartment in the Spotmatic is "upside down" to what you might expect.

The battery cover is marked with a fine " - " for the negative contact of the battery, which means the positive side has to go into the compartment recess and make good contact with that small terminal inside. This is why the battery needs to be so small, and why you need some kind of gasket around it to keep it aligned. Original batteries had a wide metal flange attached to them. Later batteries made to fit the Spotmatic had a plastic gasket surround, usually clear or blue coloured. The plastic gaskets can be pried off dead batteries and re-used with a new silver oxide battery that fits (usually that 394 size).

So, yes, if you put the battery into the compartment the direction it looks like it goes, you will have reversed polarity, and the meter won't work.

Thank you! This is SO good to know. I had to remove the corroded battery and after cleaning up the spin on cap I couldn't see a positive or negative sign on it to know how to orient the battery.

[Helios 1984]

Congrat on your recent acquisition, the Spotmatic is fine camera. Concerning the battery, you can wrap teflon tape around it or use a O-ring to fill the gap in the battery compartment.

[Xmas]

normal plumbers o ring is ok I use hearing aid batteries as voltage is close to mercury and you can get them on Sundays