Workings of the mirrorbox mechanics - Nikon D3

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Workings of the mirrorbox mechanics - Nikon D3

Postby ragnor » Tue May 16, 2017 6:11 am


This isn't quite 'external', nor is it firmware, so I'm not sure I've put it in the right place.
A colleague and I picked up a broken D3 and are attempting to fix it. It's got an 'err' message, the shutter doesn't recock itself and the mirror stays in the up position.

We got pretty far in debugging the thing and disassembled it mostly.
After removing the front body, the shutter would cock itself. The unconnected and unpowered front body still had the mirror in the up position.
We further disassembled all the way down to the mirrorbox. We think the root cause is in the mechanics of it.

This is a picture of the mechanics on the mirror box:

What we've noticed is that the solenoid on the left has a permanent magnetic field, the solenoid on the right does not. If we hold the lever attached to that right solenoid, we can keep the mirror in the down position. We think both solenoids require a permanent magnet and the one on the right somehow lost it's magnetic field (clueless how that could happen).

What I actually want to ask is; has anyone disassembled their DSLR down to this level and figured out how it works? Is the right solenoid supposed to have a magnetic field, or are we missing something?
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Re: Workings of the mirrorbox mechanics - Nikon D3

Postby Silentg » Sun Jun 11, 2017 11:25 am

Message this guy:

He had the same problem and fixed it. There are a couple other relevant videos on his (still active) Youtube.
I'm glad my running across his repair 3 years ago has finally helped someone out.
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Re: Workings of the mirrorbox mechanics - Nikon D3

Postby Lifegiant » Sun Jun 18, 2017 6:01 am

I had a D3 shutter quit on me mi bracketed burst. After about a minute of thought and finding all the rubber and a shutter box on EBay for $70$, I went for it. The shutter, as I'm sure you know has 2 curtains open close, recock reset. I tried manually getting the magnetic solenoid to cock in place, it would not. I have a kinda of hook up in Melville, as a Nikon NPS Member, he stated the following: 100's of 'dead shutters comer in for service, in my 8 years I have yet to see it be anything but the 'Actuator' that's is controlled by magnetic charge.{say for a full sensor cleanings gone wrong and bending the shutter}.' That said my repair {w/ an existing 900,000 activations on unit, and over 1M on the used assembly, honestly I concluded that there have to be specific reason to why the 'actuator', which looking at a D3 schematic, seems to be the assembly you speak of, other than the magnetically controlled resettting of the arm that moves the shutter back to 'cocked', it's totally basic mechanical spring, lever, latch, in design. So there should be a part to be replaced, but honestly shutter boxes can be found so cheap, I'd just replace it assembled.{. If anyone want to take this further on a programming level, in live view mode the D4 shoots Q or S(silent) photos. Silent shoots faster than its 11fps rating- although it's Jpeg only, I was rather curious, if some how the same couldn't be activated in a D3. Just a thought), Anyway So I swapped shutter boxes replaced the rubber grips ( refinished the nicks/wear, on it w/ black nail polish & it looks nearly new), but I kept a 2nd body the seller 'threw in' with a scratched sensor,( sadly from pushing the shutter up ) & obviously missing the shutter box and aperture ring. I thought if I could could replace the actuator, I'd remove the AA filter & be done. I've got a that D3, and if there's anything anyone here needs, I'm happy to donate in the interest of the great things I've gotten from Nikon Hacker, I believe rhat may apply to #Astronomer as well who did the video (I believe), but inbox me if you need anything, peace! ( btw i put 100K on that D3 and it sits 2nd string to my D4, D7000 in a catastrophe)
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