brian_donaldson3

I did make voltage measurements before and after. Before levels were 3.15vdc with the switch on and measuring across the battery wires. After installing the diodes I measured 2.9vdc at the same location. This is without a load on the meter, meaning no light. With the diodes in, I can now adjust the Meter Sensitivity pot on a known shutter speed, aperture, and ASA (I love using that instead of ISO - LOL). As for the other FTn, I took it apart and immediately found the CDS Sensitivity Pot was maxed out. I put the wiper where it should be (SWAG based on where the wiper is on the other FTn) and am now getting light readings. Still need to do a few other things but I think I can get this FTn working. Whoot! The luck of the Irish is with me. LOL

Yes I did. Took using a set of precision screwdriver that look to be JIS compliant. Plus some more Isopropyl Alcohol. Thanks

Now I am officially finished. I installed 2x BAT41 Schottkly Diodes in the lower unit of the meter. This in theory will drop the voltage down to usable levels for the meter. After installing I tested the voltages and they are just +/- 1.5mv depending on where one takes the measurement. Here is an out of focus (handheld) image of the installed diodes. The diodes are in the white heat-shrink tube. They are placed in series and the cathode of the lead diode is connected to the brown wire from the battery compartment. Installation was a little harder than I expected because the solder is so old. Took some patience to heat it up to melting point. So this is a wrap. Next project is another FTn that I purchase as parts/repair. The battery test works on this new FTn but it does not have any activity other that the test. New challenge. Should be fun.

I noticed it on my name and on several others. Mine is |3 and I don't know what it means. Anyone?

Question and not a suggestion, but would Hydrogen Peroxide have any affect on mold or the shutter cloth? I know Hydrogen Peroxide can be used to clean fungus out of lens and such. Or how about a non-whitening bleach? Just curious.

Yeah, my bad. I see that now. Good catch. So I stand corrected. :)

Thanks, mwmcbroom.

No, you are 100% Matt. It is much better to have a battery solution than a hardware solution. However, I feel that if the solution I have in mind works then I do not have to worry about this anymore. Nor will the person who gets the camera next. All they need do is insert two S625PX batteries and be done with it. I still have the ring option on the table. And lastly, a minor modification to the MS pot can also solve issues, but that is so far from now that I am not even thinking on that level. The diodes should be here tomorrow afternoon. I should have them in by Tuesday and I will post an update.

Hi Matthew, I use that very document to study the FTn meter function. That, and making measurements with 2x PX625A batteries I have concluded that the Meter Sensitivity (MS) pot does not have enough resistance to support anything above 3v. Right now my MS pot is to the far clockwise rotation meaning it is at its maximum resistance and I still cannot achieve center swing. The require voltage (according to the document) for center swing is .134v at the resistor with .109 voltage drop and .025v at the meter. I am getting .035v at the meter side of the MS pot. So there are a couple of options. Change out the MS pot with a higher resistance pot allowing the use of higher voltage batteries. Get the rings that Robert mentioned @ $36/ea to use different batteries and bring down the voltage. Get some rings from PX625 Battery Adapter <battery.adapter@online.nl> @ 16eur/ea ($19.56) if paid by Paypal. Make my own rings using BAT43 Diodes to achieve a voltage drop. Install in the meter a voltage dropping device such as a BAT41 Diode. At this moment, I have ordered BAT41 Diodes and will go with that option. Two diodes in series should (according to documents I have read) result in the correct voltage for the meter to function correctly. Just so you know, the meter is indeed working. I am just a stop too high. That is fine for me but if someone else uses the camera they will not know this. Appreciate the comments and recommendations. Even though I am sure I own the solution for this, it is good to have a record for anyone else who is considering doing their own CLA or even trying to repair their FTn meter,

Prism removal. He also has a blog on how to remove the DE-1 prism. Just in case anyone is interested in removing their prism.

Good info Robert. I will keep looking for a solution that works for me. I can't justify $75 for adapter rings with a diode in them. Just not cost effective.

Thanks @mwmcbroom for the tip and information. I read about the 675 but have not tried them. I am game to try anything just to see what it does. Well, almost anything that is within a reasonable voltage range for the meter. I was at WalMart today and forgot all about the batteries. I just received a pair of Silver 625 batteries. I understand they last the longest. I'll look for a pair of 675's next time I am out an about. Thanks again. Oh... yes the FTn's positive is a small tab on the side of the battery compartment. The cap does not make contact to the best of my knowledge. Tomorrow I will tape off the tab and see if the cap is making contact.

Mission accomplished. The meter has been CLA'd to the best of my ability as a non-camera tech person. The issue I was having was the meter would register low light, but in a bright light situation, the needle would peg all the way to the left. This was with new batteries (PX625A). .I took the meter apart and cleaned up the resistor ring, all the electrical contacts, removing corrosion around the pos battery lead, and finally cleaning and sliding the pot for meter sensitivity and battery test. Put the meter together and still had the same problem. Today I figured that either I had too much voltage (note: the PX625A are 1.55vdc batteries. The meter uses 1.34 volt batteries but they are expensive and hard to come by, even the MR-9 Adapter is expensive) or I had a light leak requiring me to refoam the FTn meter. Well, I decided to check the meter again using as a metric my F2AS (serviced by Sover Wong) and my Canon 5D Classic. Inside the house I metered the white wall in bright sunlight with the Canon and the F2AS and they both agreed to speed, aperture, and ISO. I then setup the FTn to the same setting and it too matched. I was happen, but I was also in a low light room. Next, went outside in the bright sunlight and this time only used the F2AS as my metric. Wow, something changed because the FTn is no longer pegging to the far left. It too matched the F2AS, but not exactly. Looks to be about a stop overexposed. Minor tweak of the meter calibration pot should fix that. So, like I said, mission accomplished. However, I did notice what appeared to be some of the coating on the resistor ring is thinning out. :( might have to look for a broken FTn head and steal some parts. :)

My guess, Ben, and it is just that, a guess, would be that the prisms are the same. Simply from a production standpoint and repair standpoint. Cost of maintaining different products for like equipment was eat away at profits. It would seem more cost efficient if the four items, DP-x, DE-1, F prism, and F T(n) all used the same prism. This would make having spares available for any of the four finders. But there are actually more than four finders, right? So again, I would say that they probably are interchangeable. Just my opinion with no evidence to back it up. However, why not just resilver the prism and have a "like new" prism.

Robert, thanks for the Micro Tool suggestion. Now that I have 2x F's and 2x F2's, I think I should really break down and get some decent tools. Gus, after looking at the head of the screw under 25x magnification, the damage is not that bad. For the screwdriver I was originally using, yes, it did do damage. However for the other screwdrivers I found, there is plenty of slot space and I can still move the screw about. The head will probably need a good filing to smooth it out. That is another challenge with a screw that small. But I am up to it. :)

Thanks cees jan de hoog. I had thought of that also but without a good screwdriver, which I seem to lack, that cause more problems. However... drum roll please... a new update. While looking for something totally different I found a set of precision screwdrivers that were made in Japan. The smallest being .9mm and with long, flat profiles. I used the 1.2mm screwdriver, in concert with a continuous bathing of 91% Isopropyl Alcohol and bam! the little sucker started turning free. However, the head is a disaster and I will have to replace that screw. (added - I used a squeeze bottle with a needle to deliver the Isopropyl Alcohol) With much thanks to the community, I will continue my adventure into a CLA of my F Tn meter. p.s. I am still looking for my can of PB Blaster. I know it is around here somewhere. I use it and other thing to work on my dinghy outboard.

Well it looks like I will need to come up with a plan B. I looked with high manification and the top of the screw head is stripped. Because of its tight working area I am not sure what I can use to extract it. Maybe a jeweler can get it out. I will keep soaking and later use heat.

I have PB Blaster - I'll try that. Thanks I have lots of different wattage soldering irons - I'll also try that also. Thanks The smallest screwdriver I have is 1.4mm. That might be too big. Maybe I'll look for a smaller head like 1mm. Hard the check the profile without a 10x magnifier. LOL - Thanks

I am working on a CLA of my Photomic F Tn finder. I can get all the super tiny screws out except 1, which seems locked in place. Once I get this screw out I can separate the two halves of the meter. This tiny screw will not budge. I have tried soaking (with a q-tip) in 70% Isopropyl Alcohol and it still will not budge. I plan on soaking (carefully) again with a needle bottle this time in 91%. Any other suggestions? Maybe really cold can air to hopefully contract the screw just a wee bit? My biggest fear is stripping the top of the screw head. Much thanks in advance!

LOL I knew that. Just checking to see if you were paying attention. (I also knew I had the wrong name but couldn't remember Cosina... thanks for the correction).

I think for the FM10/FE10, the reason it is odd man out is that they were not made by Nikon. But made for Nikon by Contax.

I put an SD card in backwards in a D300. Went right in. Couldn't believe it. A young lady got it out for me. She had smaller fingers. Personally I would use a dental pick with a sharp point. He said he didn't care about the card.

I gave up looking for an adapter. I thought about the DK-22 but didn't want to waste anymore money. As mentioned above, the best course of action is to just get a complete F that has the eyelevel round frame. That is what I am doing. I have an eyelevel with a rectangular frame and it is in superb condition. I plan on listing it on eBay when the other F arrives. So that will make it 2xF and 2xF2. Whoot. LOL

Sandy, like I said above, not all the F eye level finders had round windows. There are three examples that I have seen like I mentioned. My F2 and my Photomic FTn all have round viewers, but my F prism does not. Graham, thanks for that info. So something does exist for the F with the rectangular frames. The search is on!

This question is not about the weird way Nikon's corrective lenses work. I already did the reading glasses trick and found the right diopter for me. This is about the Nikon F Eye Level finder and getting the correct sized frame. I have seen three different examples of the eye level finder. One, might be newer, uses the round frame. One, uses the rectangular frame. And one uses an almost square frame. My eye level finder uses a rectangular frame. However, my Photomic FTn uses a rectangular frame with round threads. So the diopter I have for my F2 fits fine in the FTn. But it will not work on the eye level finder. Does anyone here have the F eye level finder with rectangular frame and using a corrective lens (not eye glasses). The frame size is .975" x .75" (24.73mm x 19.05mm). Or have a Nikon camera that has that size frame for the eye piece? Thanks