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Nikon F4 aperture lever repair

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F4user

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F4user submitted a new resource:

(there was a url link here which no longer exists) - Nikon F4 aperture lever repair


(there was a url link here which no longer exists)
 
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F4user

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Episode 2 - right side cover

Right side
5: Remove ornament cap of exposure compensation knob
5.1: Remove the screw & knob
5.2: Remove 3 screws of indexing plate.
5.3: Remove mode selector.



6: Remove shutter speed selector rubber. Attention do not scratch paint of knob. Insert slot screwdriver at the bottom of knob and use a round tooth stick to remove the rubber

7: Remove 3 screws placed at 120 degrees around. Use 1mm slot screwdriver. Do not loose too much, one turn at a time each until the knob is free. Pay attention the screws are very small. Do not loose the spring inside.

8: Using two 1mm slot screwdrivers remove clip ring 8.1: Remove illuminator lever

9: Remove red dot and the screw.

9.1 Remove right side cover screws and right cover

Mandatory - see the next post. Forum's limit is 15 pictures per post.
 
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F4user

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Attention to this pin. Do not loose.
 
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F4user

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Episode 3 - more work

Bottom cover

10: Peel bottom rubber. The rubber is attached using double adhesive tape. Start from battery side, start gently. Insert a small slot screwdriver between the rubber and brass sheet. Between rubber and the bottom case there is a brass sheet also attached with adhesive tape. Pay attention and do not peel the brass sheet, you will have more work to do. Press the brass down with a slot screwdriver. Plastic knife can be used.


11: Remove bottom cover screws


12: Remove bottom cover. Start from battery side. Lift gently and with care. There is adhesive between brass sheet and tripod nut and allow time to peel off. Pay attention to the wires. Do not insert any tool between bottom cover and the rest of the case, most of the electronics are there.


13: Using soldering iron remove the connections. Pay attention to static electricity. Do not wear plastic fabrics, use only cotton and do not wear plastic shoes. For ex: touch metal case of a running PC to discharge static electricity. Avoid excessive movement on the chair where you stay to avoid recharge with static electricity. From this step forward this precautions apply to all steps because the electronics will be exposed.


14: Remove tripod socket plate. Pay attention: the screws have thread blocking paste. Apply increasing force until they start to move.
14.1 Remove more connections ( 2 black & 1 orange wires on left side and all on the center ). Peel black acetate tape up to the dotted line only. Remove flexible band connector with small movements ( green markings ) keep parallel to the socket. Pay attention to flex cable.


Top .. less.

15: Remove shutter button assembly screws. Keep them close for reassembly. Remove LED connections ( green and orange ) .


15.1 : Gently lift shutter release button assembly ( screws side ). Pay attention to the flex cable on the front. Lift as much is need to insert a screwdriver to remove battery plate screws. Reattach shutter button assembly using the screws
 
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F4user

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Episode 4 - Big split

I recommend the back film cover to be in place to protect shutter blades.

16: remove right side and left side rubbers


17: Remove right & left side rails and the screw near right side rail. The right side rail have some light seal sponge over it. Cut it clean after screws removal.


18: remove cover and pressure plate over flex cable contacts


19: Remove front screws. Don't touch the screw with yellow marking. Remove all ( 7 ) electrical connections near focus mode selector


20: Remove side screws ( left & right ) and back


21: Remove LCD - LED assembly screws. Gently lift the assembly starting from grip side no more than 3-4 mm. Pay attention to the flex cable on the ISO side, the flex cable is short . Lift the assembly until is free from its position.


Take a break. You need it

22: Now you can start split the camera. Pay attention to the flex cables on battery side. Keep them inside the case with fingers or a small plastic tab. When the cases start to split swap over the case the flex cable of LCD-LED assembly. Pay attention don't break it.


Gently move the front case up, down left & right until complete split. Now you can admire Japanese technology.
 
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F4user

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Episode 5 - Who killed JR Ewing

Inside job.
As you can see the mirror mechanism and aperture lever are pure mechanical with no motor.

The mechanism from back side of the F4's body push 2 levers toward front of the body , one for charge ( green ) and another for shoot ( blue ) releasing mirror mechanism and aperture lever mechanism, both are spring actuated. Pushing the lever ( green arrow ) will charge the mechanism. Push release lever ( blue arrow) for shoot mode. The aperture mechanism must follow the mirror mechanism and is more complicated having a lot of toothed gears.



The culprits for defective work are: aperture lever spring and hardened shaft grease of toothed gears.
The aperture spring is under PC board and is hard to take a photo of it. Will come.

Charged position look like this:



Observe mirror lever ( pink arrow ) secondary mirror ( purple circle ) and aperture mechanism ( yellow circle )

Release position:



Observe mirror lever ( pink arrow ) and aperture mechanism ( pink circle ).
The lever is in touch with the aperture lever adjusting screw.
When all mechanics are in released position you can play ( move ) the aperture lever with your finger to see if the movement is fast. Also you can charge - discharge mechanism to see if the aperture driving mechanism is fast enough to follow mirror mechanism. Pieces shown as in the picture above must move together or very close. Total time must be under 20 ms and that's fast, hard to see.

Faulty position because stuck gears:



Observe " mirror up " position ( green ) and aperture mechanism in charge position behind adjusting screw.

The repairs.

First remove the circle clip of the first gear and remove the first gear.
Pay attention to the rest of gears, they start to spin up fast.



Remove screw of the plate. Be careful there is a spring under brass gear and can escape in the room.



Clean the remaining gears shaft pouring some cleaning fluid. Also clean riveted mechanism
I use for everything, even for lens, MOTOREX brake cleaner. http://www.motorex.com/index.cfm?oid=1147&lang=en&eintragId=123&webtoolDbTemp=eintragDetail


Repeat until gears and levers move easy. Oil with clock oil a very very small quantity
I think is not necessary to say removed gears need also cleaning.

Aperture mechanism:



The aperture spring soften with time so there are 2 possibilities : change or adjust the mechanics. ( next episode )
 
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frank

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Wow, thanks for posting this. I paid $100 to have this repair done on my F4. Money well spent in my case.

This damage was caused to my camera by using a lens with a sticky aperture.
 

camtec

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Excellent article. Very well done. Larry Lyells would be proud. BTW, I am a camera technician.
 

NiCad

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Thank you for taking the time to write these instructions.

Is the aperture spring available to purchase somewhere? Any stores that sell Nikon parts?
I assume fitting a spring with OEM specifications in order to maintain the correct spring rate would be advisable.
 

EIJU YUASA

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Andreas Thaler

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A follow up to this thread see here:

Nikon F4: Mission Aperture Lever - two ways to fix the aperture problem

{Moderator note 12 Jan 25: five threads on the F4/F4S aperture lever repair have been merged into the present thread. You may encounter one or two dead links to 'other' threads. The posts they pointed to, are now all part of this thread, which mostly still follows the journey in a logical and...
www.photrio.com
 

Andreas Thaler

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Joined
Nov 19, 2017
Messages
4,662
Location
Vienna/Austria
Format
35mm
More follow-ups:

Nikon F4: Mission Aperture Lever - two ways to fix the aperture problem

{Moderator note 12 Jan 25: five threads on the F4/F4S aperture lever repair have been merged into the present thread. You may encounter one or two dead links to 'other' threads. The posts they pointed to, are now all part of this thread, which mostly still follows the journey in a logical and...
www.photrio.com

Nikon F4: Mission Aperture Lever - two ways to fix the aperture problem

{Moderator note 12 Jan 25: five threads on the F4/F4S aperture lever repair have been merged into the present thread. You may encounter one or two dead links to 'other' threads. The posts they pointed to, are now all part of this thread, which mostly still follows the journey in a logical and...
www.photrio.com
 
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