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Frecciadelledolomiti
Tinkerer
Username: Frecciadelledolomiti
Post Number: 1
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 26, 2008 - 09:53 am: | 
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Hello to Everyone.
This is my first thread, I hope to find here some answers to my trouble.
I own a Photomic Tn meter that doesn't work properly.
It gives wrong readings.
It responds to ASA and shutter changes but does not to aperture.
Moveing the coupling hook from max to min aperture makes no difference while changing shutter speed only one stop does (or ASA as well).
The aperture mechanism is all linked as it should and it moves the inside lever around the main wheel in the Photomic body.
Can anyone help me ?
Bateries are new 2 x 1.35V Wein.
Sorry for my not-very-good english.
Thank You. |
M_currie
Tinkerer
Username: M_currie
Post Number: 121
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 31, 2008 - 08:59 am: |
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I was hoping someone else would respond and give you some good advice. I've been inside an FTn, but not a Tn. On these, both the aperture and shutter speed combine to turn a large ring resistor, and if the resistor fails, you'll have problems. But if the shutter speed dial causes smooth needle movement, I doubt that's your problem. I think you probably will need to open up the meter head, and see if there is a linkage broken or dislodged. You could start with the front cover, which should reveal the linkage to the lens. If all looks connected and in order there, you'll have to remove the meter cover. There are screws hidden under the leatherette cover on top, and some screws underneath, and it should not be too hard to figure out which ones must be removed to get the skin off the meter head. Unfortunately, I do not know of any reference for this model. Just take care and take notes. The mechanism is mechanically a bit complex, but it's pretty large and accessible, so you should be able to see what is going on. Whether you can fix it is another matter entirely. |
Frecciadelledolomiti
Tinkerer
Username: Frecciadelledolomiti
Post Number: 2
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 31, 2008 - 05:38 pm: |
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Thank You very much M_currie !
I have to say I've finally fixed the problem.
I would say it was all about sinchro (I cannot remember how to write that word ^^ is that right ?) among the aperture ring the time gear and the ASA wheel. Infact surelly someone opened the meter since a screw that keeps the upper and the lower parts together was missing and it still.
So...
I disassembled the whole meter helped by a scheme found here http://www.ss-it.de/
and since as I said the needle was responding to ASA, shutter speed and aperture changings (ISO 400 corresponded to 1/3 stop down 100 ISO and the meter semed to work fine but not too much even if hi f number the meter said underexposure and lo f overexposure), I thought that uncoupling the two main gears and adjust the ASA and then recoupling the two gears just a little more forward or backward may lead to the right setting. Try once, try twice... and I have to say probably five times assembling and disassembling the meter, I finally found a good positioning for the gears. Then just a little touch to the tiny fine tuning screw and here it is: a well working Tn Photomic.
Tested with a Nikkormat FT2 a FM2n and a D50 the results shows no difference.
Thank You again for Your advices even if the job had already been done.
I hope this discussion would be of any help to anyone trying to "repair" a Photomic.
Bye. |
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