# Light meter not functioning



## boonjacob

Hi! 
I was a handed an old Nikon FM from by father in law. All mechanical motions seems to be working fine but the LED light indication for the light exposure (visible inside the viewfinder) won't light up! I changed the batteries with Energizer alkalines but it kinda leaked. The manual recomends "Silver Oxide". Could this be the reason for the LEDs not lighting up? Where do I get silver oxide cells?


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## compur

Either alkaline or silver batteries will work.  

You say there was a battery leak? If so, the battery chamber may need 
cleaning out.  Use vinegar on a Q-tip. If that does get it all clean you may 
need to use a contact cleaner brush to remove all the corrosion.

If still no joy, the wire connection to the battery chamber may have been
eaten through by battery leakage and would need to be re-soldered or
replaced.


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## boonjacob

I put in another pair of alkaline batteries and realized that they become kinda hot (warm actually) in a matter of seconds. The metal connector slides in and out. Isn''t it supposed to be fixed in its place. Do you get to buy a spare light meter for the FM online? (in case I need to replace this part)


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## compur

boonjacob said:


> I put in another pair of alkaline batteries and realized that they become kinda hot (warm actually) in a matter of seconds.



Not a good sign. Possibly a short somewhere.



> The metal connector slides in and out. Isn''t it supposed to be fixed in its place.


There should be no loose parts in the battery chamber.  Sounds like the 
whole thing (battery chamber) needs replacement.  



> Do you get to buy a spare light meter for the FM online? (in case I need to replace this part)


Parts for the FM are no longer available from Nikon.  To get parts you either 
need to get another junker body or find parts on eBay.  I doubt the meter 
itself needs replacement but it's possible. But, I wouldn't recommend 
trying to repair it yourself without experience and tools.  The usual result
is a baggie full of camera parts.  Probably should just find another 
working body.


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## boonjacob

Thanks for your help! I'll take it to the local Nikon service center.


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## Freelancephotog25

Could always just use the Sunny F-16 thumb rules!


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## Mitica100

Did you place the batteries inside the correct way? It's an overlooked thing and very common.


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## PhotoWrangler

Sorry to resurrect an OLD thread.... but I just bought one of these. A friend of mine and I are going to shoot film this week for the fun of it. I found an FM on Ebay for $34, being sold by a non-photog who didn't know much about it. Turns out everything works but the meter. I changed the battery, made sure it was inserted right side up, flipped the lever... and no little red LED light. There isn't any acid corrosion in the battery chamber, and it appears to be clean. The lens that it came with is the Nikon 43-86, and according to what I've learned from a Google search, its the later AI version produced around 1976/77.

Any suggestions, other than bringing it to a repair shop? I plan to take it in for a cleaning and once over soon, but until then....


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## compur

Assuming you turned on the meter and it still didn't work I would try cleaning out the battery compartment with 
rubbing alcohol and trying again.  If that doesn't work, it's repair time.


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## PhotoWrangler

IT WORKS! IT WORKS!!

After hum-drumming about the email all afternoon, and allowing the news to take the wind out of my sails, I decided that I was just going to go and pay the $30, pick up the camera, meter manually, and run some film through the camera. If it worked it worked, if it leaked light, then well... I was out $64 and a roll of film. If later on I decided I wanted to get the FM overhauled, then I knew what it would cost and I could proceed at that point.

Well, I just picked up the camera about 30 mins ago from the repair shop. I paid the $30 inspection fee, and went on my way. I couldn't wait anymore, so at a red light, I lifted the camera, took off the lens cap, moved the advance lever out the 35 degrees and voila... little red LED lights. 

I have no idea what the tech did overnight, I dont know if he simply cleaned the battery contacts, or if he reattached some wires inside... but it works.

I'm going to run some B&W film through it this weekend, or as soon as I can get my hands on a few rolls.


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## EddieFrie

I just got my hands on an old FM2N and it has the same light meter not working.  I am an electrical engineer so i know I will drill down to the problem once I shoot this roll of film off.  I did measure the four pins at the bottom of the camera and it has the battery voltage on the far corner pin on the lens side.  This does not necessarily mean there is power all the way up to the sensor yet.  I will track it down.  I know there are two other paths that are involved.  The ISO/ASA switch and the power switch.  Both are easy to isolate and measure too.  I will report back in a few weeks when I figure this out.  It is a fantastic camera and I am looking forward to.  There is a very small possibility that the electronics have gone bad due to oxidation.  I doubt this though since the other switches are more error prone due to wear.


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