Jump to content

FM Battery Issue


exaktamoment

Recommended Posts

I have an FE that works perfectly and it uses the same battery setup that the FM uses. So, besides my voltmeter, this is my test bed for batteries. So. I went to the battery store and bought a brand new 2L76. That's a single 3v battery that is the other proper one to insert in the camera. And it worked. It tested at 3.26v and initially, it worked. I had LEDs as soon as I turned on the camera, I cocked the shutter and fired it and I still had LEDs but I cocked and fired again and the LEDs went out. I pulled the battery and tested and the battery showed 2.78v. So riddle me this, Batman - in a camera that's Fully Mechanical, in which the only thing that the battery is used for is the light metering system, how is it that battery drain seem co-incident with the shutter being fred?

 

What is there in an FM than can short and drain the battery?

Link to comment
Share on other sites

I think you can leave the meter on for a while then the battery would be dead. When the battery read 2.78V without load that's dead. And a fresh battery is dead in the matter of minutes the short is severe.

 

The manual says "a few days" although I've never tested it.

 

I don't know EXACTLY how the metering circuit in the FM is laid out, but any time the meter is on it will draw power since it has to illuminate the LEDs. With a CdS/galvanometer meter as on all the F metering prisms and the most common F2 prisms(DP-1, DP-11) putting a lens/body cap on will have much the same effect as turning the meter off. In fact, the very first F Photomic meter just had a flap("flag") that was raised and lowered to cover and uncover the metering cell.

Link to comment
Share on other sites

The manual says "a few days" although I've never tested it.

 

I don't know EXACTLY how the metering circuit in the FM is laid out, but any time the meter is on it will draw power since it has to illuminate the LEDs. With a CdS/galvanometer meter as on all the F metering prisms and the most common F2 prisms(DP-1, DP-11) putting a lens/body cap on will have much the same effect as turning the meter off. In fact, the very first F Photomic meter just had a flap("flag") that was raised and lowered to cover and uncover the metering cell.

If there is no short and you leave the meter on the battery would be dead in a few days. But as the OP said it's dead in the matter of minutes then there is a bad short. The fact that with the old batteries the OP could get it to work by not screwing the cap in too tight I think the problem can be fixed relatively easy as the problem is only where the battery compartment. Removing the baseplate may reveal the problem.

Link to comment
Share on other sites

I talked to a friend of mine and he suggests I would probably be better off to just get another FE or FM - it would cost more than a substitute camera to ship and repair the wonky FM. I'll do that, I suppose, but I'll keep the FM in hand - to see if I can fix it myself.
Link to comment
Share on other sites

I talked to a friend of mine and he suggests I would probably be better off to just get another FE or FM - it would cost more than a substitute camera to ship and repair the wonky FM. I'll do that, I suppose, but I'll keep the FM in hand - to see if I can fix it myself.

I think you should try to fix it yourself. Remove the base plate and check the battery compartment. It is possibly when the cap is screwed in tight it pushes the battery compartment inward a bit and the bottom of the compartment may hit something.

Link to comment
Share on other sites

I think you should try to fix it yourself. Remove the base plate and check the battery compartment. It is possibly when the cap is screwed in tight it pushes the battery compartment inward a bit and the bottom of the compartment may hit something.

BeBu, I probably will - I'm certain I'm not going to send it out to repair. As I said, it would cost more to ship and fix and ship back than to just get another camera. That said, I AM curious as to what is wrong with this beast and I think it would be cool to figure it out for myself.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...