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Jimwilson
Tinkerer
Username: Jimwilson
Post Number: 1
Registered: 05-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 25, 2007 - 11:56 am: | 
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I got what seemed like a fabulous eBay deal on a beautiful condition Nikon FG body. I've been using Nikons for decades, and love them. I thought the FG would make a very nice little carry-around camera which could use my Nikon AI lenses.
The seller sold it "as is", which usually doesn't mean much, as a lot of these guys know zilch about cameras, and it's often just a dead battery. (This seller specializes in baseball gloves, for example)
However, when I shot a test roll with it and saw the results, there was obviously a film advance problem. Inspection showed that the film rewind button in the base plate didn't pop back out as it should, when starting and advancing the next roll. This was obviously the problem. I applied a drop of WD-40 to it, thinking it might just be binding from something superficial, like dust. No dice, though- still no pop out. So it's obviously internal.
I'm a pretty handy guy, but I'm a bit timid about tearing into a Nikon, just to see if I can figure it out myself. So, I took it to PhotoTech, here in Manhattan, told the guy at the counter the problem, and asked for an estimate. Rather than just calling to find the result, I walked over to get the news in person today, thinking I'd probably be bringing it back with me, unfixed.
Sure enough, they gave me a laundry list of the stuff they wanted to do to it, including replacing all the seals, recalibrating everything, in addition to fixing whatever's causing the button to bind. The total came to about $150. Since I've recently ordered a lifetime supply of light seal and foam materials from Jon Goodman, knowing that this, and several other old non-F bodies I have would be needing it, I wanted to do that job myself, and my test roll showed that the metering was working fine. But,the counter guy said they wouldn't do the job without doing everything on the laundry list.
The way prices for FG bodies are running on eBay, I could easily buy three more of them, with short guarantee, for that price. So no way I'm paying out that much to fix a $30 body.
I'd still like to fix this one myself, because it's so clean and nice except for the rewind button problem. But, I'd still be timid about tearing into it without some input.
So, have any of you brilliant and more experienced guys here dealt with this problem, and do you have any tips for tackling it? I sure hope so! |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 286
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 25, 2007 - 08:29 pm: |
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First just try pulling off the baseplate and looking. I don't have an FG, but there's usually a little lever thing down there that grabs the button and holds it in, and this retracts when you advance the film. There might be something visible causing it to stick, and you might be able to fix it in a minute.
Go very easy on the WD40, though. I won't say it NEVER does any good, but it's pretty safe to say it's never good to put it where you can't see exactly where it's going. If you have to try dripping something blindly into an opening as an experiment, use cigarette lighter luid... that evaporates away cleanly and is unlikely to cause new harm (even this should be done only with great caution, though, as you can cause problems even with lighter fluid in the wrong places) |
Jimwilson
Tinkerer
Username: Jimwilson
Post Number: 2
Registered: 05-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 26, 2007 - 01:34 pm: |
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Hi Rick,
Beneath the baseplate, the rewind button has an inverted-T profile, like a top hat. I presume that a shaft from it extends deeper into the mechanism. A small leaf spring is fixed to the chassis by a single screw. The shape of the spring's base is such as to register its location and attitude within the chassis. The arm of the leaf spring, bent at a right angle to the base portion, appears to be a keeper, to prevent the button from emerging too far when the baseplate is removed. However, when the leaf spring is deflected so it clears the "top hat's" "brim", the button doesn't show any inclination to pop up, with or without activation of the advancement lever. With the keeper arm deflected, I gently tugged up on the button with a pair of right-angle needle-nose forceps, with hardly any movement resulting. It's not just friction or congealed lubrication preventing it from emerging further to full extension, but something mechanically positive.
I was visualizing something like a bevel gear on the button's shaft which would normally engage a matching pair in the advancement gear train, which would engage with them, until pushing the button would "release the clutch". It's impossible to see if that's the actual operation, though, without considerably more disassembly.
I used barely enough WD-40 to lubricate the button only within its baseplate opening, in case some small particle could have been jammed in the opening. Unfortunately, there was no lint or dirt jammed there. Too bad, as that would have been easy. I'm starting to see why the repair shop wanted that much money to go in there. Deeper access would be very complicated to accomplish.
Thanks. |
Ethostech
Tinkerer
Username: Ethostech
Post Number: 69
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 29, 2007 - 11:48 pm: |
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It's a fundamentally simplistic arrangement.
Depressing the film rewind button declutches the film-transport toothed sprocket so that it free rotates upon fim rewind.
When the film advance lever is operated, the button is released and the sprocket clutch re-engages under spring pressure.
Best thing to do is remove the camera baseplate. You will then see what is holding the rewind button "IN". Operate the film advance lever and look for a an interface movement which is designed to remove the button arrest.
There are no complicated gear-trains or rocket science stuff about the Nikon FG film-rewind detent. Whatever big dollars the repair-shop wanted - the quantum had little to do with the specific problem which you cite. |
Jimwilson
Tinkerer
Username: Jimwilson
Post Number: 3
Registered: 05-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 31, 2007 - 12:30 pm: |
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I removed the baseplate again, and looked pretty hard in there, and again there's not much visible of the mechanism which pops the button. The button revolves during the film advancement stroke. During the stroke, the sliding pawl which cocks the shutter travels to almost the end of its travel, then snaps back when the end of the stroke is near. I presume that if the button were at full extension, the film would advance, but there's no way that button's reaching full extension, even when physically pulled during any stage of the rewind stroke. And there's no mechanism visible below the button, due to that level of the chassis concealing everything beneath it. |
Jimwilson
Tinkerer
Username: Jimwilson
Post Number: 4
Registered: 05-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 31, 2007 - 12:38 pm: |
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I removed the baseplate again, and looked pretty hard in there, and again there's not much visible of the mechanism which pops the button. The button revolves during the film advancement stroke. During the stroke, the sliding pawl which cocks the shutter travels to almost the end of its travel, then snaps back when the end of the stroke is near. I presume that if the button were at full extension, the film would advance, but there's no way that button's reaching full extension, even when physically pulled during any stage of the rewind stroke. And there's no mechanism visible below the button, due to that level of the chassis concealing everything beneath it. |
Krp
Tinkerer
Username: Krp
Post Number: 37
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 02, 2007 - 09:48 am: |
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Your problem lies in the top of the camera. There is a film advance unit under the top cover. The advance lever attaches to to post of the unit. This unit has the frame counter attached to it and the counter switch that turns the camera on when the counter reaches '1'.
Under the film advance unit, there are two things. The top of the spool gear and the drive gear for the tractor sprocket.
If the drive gear (the brass one) for the sprocket doesn't move when you advance the film, the rewind release button will remain in the released position.
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