A trip inside the D810 to fix it.

D200freak

Senior Member
OK, don't expect me to post a lot of photos tonight but I'm setting this topic up for me to add to it over the next couple of days.

I bought a damaged D810 for the princely sum of 775 dollars delivered to my door, knowing full well what had happened to it.

The previous owner had left the lens on the body, placed it in its Pelican case, and entrusted it to the tender mercies of the Delta Air Lines baggage handlers, who were apparently former American Tourister test gorillas.

They managed to abuse the case hard enough that the lens ripped the lens mount out of the camera. Not TOTALLY out, but yes, serious damage did occur.

The face of the camera, a plastic skin, destroyed. The mirror box, a central component of the camera, badly broken beyond repair.
The LCD, working but very erratically. No evident damage to the back, sides, top, or bottom of the camera.

Delta paid the guy for a new camera and he sold the damaged one to me. It was actually on ebay and I made him a cash offer for it,
which he accepted as it was slightly higher than some others he'd gotten.

In retrospect if he'd let the auction run I suspect he'd have made more off it than I paid for it so I'm happy he took my offer.

When I got the camera I did a teardown to evaluate the damage and determine what had to be replaced. I'd already ordered a new front skin for it, there being no doubt that that was going to need replacing.
D810busted.jpgDSC_5738.jpgDSC_5743.jpgDSC_5741.jpgDSC_5745.jpgDSC_5749.jpgDSC_5752.jpg
It didn't take a lot of investigation before I knew I'd have to get a new mirror box for it. So I ordered one up from an ebay seller in China. It arrived a few days later, surprisingly quickly, and was in fine shape but wasn't as complete as I had hoped for. So, I had
to transfer over several components between the broken mirror box assembly and the replacement, which was less complete.

A brief diversion to explain the general design of the camera and a few observations about the assembly and disassembly process:

All disassembly of a D810 starts by removing the bottom of the camera first. There are several screws hidden under the rubber bumper on the bottom, so that has to be carefully peeled off and set aside first. Other screws are hidden in the battery compartment, and there are several kinds of screws used and their lengths vary. It's important to try to keep from mixing them up, which is very easy to do.

Once the bottom is off, it's possible to remove the front, back, and sides. On the front, you have to remove the rubber piece on the left side of the camera (as you hold it as you are about to take a picture) to access hidden screws. There's a screw on the bottom, and there are two visible screws on the face of the camera above the lens mount. Very importantly, there are also two screws hidden inside the pocket where the pop-up flash resides.

But wait, there's more! There are screws that hold the front on which have to be removed and are accessible only after you remove the door and cover assembly for the CF/SD card reader slots.

So, the disassembly order is to first open all the doors on all sides of the camera and take out every screw you see. Remove the back panel (one screw under the rubber grip on the right) and then remove the door assemblies. Watch for screws. The left side door assembly can't be removed until you remove the left side front rubber grip piece first and pull out the screws hidden under it.

So, bottom off, back off, sides off, front off, now all the screws that hold the top on are visible, except the one hidden one.

That hidden screw is behind the center cap of the eyepiece focuser. Pop this cap out and remove the screw under it. Now the focuser knob comes off. NOW the top can come off. Carefully release the electrical connectors on the main PC board. The ones with the blue wires pop off vertically. So does the one with the black wires. All the flat flexible cables slide straight out of their connectors, and most have tabs that you gently lift to the vertical position to release pressure. A few require the locking tab to be slid outwards.

With all connectors released, lift the top off and flip it over to the left like it's got a hinge on the camera body on the left side. Then follow the two remaining cables attaching them and gently pop their connectors out. Warning: The red and black wires go straight to the photoflash capacitor. That stores enough energy to really knock a hole in your day. Pop the connector straight out and don't try to touch the exposed pins in the connector by the capacitor. Just leave it alone. You can render it safe by shorting it using the lead of a pencil. But it WILL make a loud snap and a spark when you do that. Don't use a metal tool. Use a pencil lead. You won't get shocked that way.

General construction notes: The main PC board mounts to the back of the shutter frame. Underneath it is the image sensor, which is positioned exactly on the focal plane using spring-loaded adjuster screws. Leave this alone! While it's not a horrible job to realign the sensor, there's no need to remove it and thus no need to have to worry about realigning it.

The main guts of the camera consists of the mirror box and the shutter frame. They're held together by about seven major screws and a few smaller ones which mostly help to secure certain flexible circuits where they need to be. When all flexible connectors that are involved are released, and all retaining screws are removed, the mirro box assembly easily separates from the shutter frame and now you basically have a front half and a back half of the camera.

Note: Force is NEVER needed to assemble or disassemble the D810. If things are not coming apart easily, there's something still attached or connected that's causing it. Don't pull harder, FIND IT.

On the bottom of the shutter frame, there is a shield blanket that has to be released before the camera can come apart. Pull the screws that hold it in place before attempting to separate the mirror box from the shutter frame.

I always recommend reinserting screws right back where they came from as soon as parts are released. Then you don't lose them and you know where they go.

So, that's the basics of how the camera is assembled.

An interesting part is the autofocus assembly. You really can't see it when you take the lens off and look inside the mirror box, but it's there, hidden in the back, behind the mirror, on the bottom.

What you may not realize is that the main mirror is semi-transparent. SOME light passes through it, and that light is directed, via a SECOND mirror, downward to the autofocus sensor assembly.

It's due to the fact that the AF sensor assembly sees through this partially reflecting mirror than AF does not work so well in dark conditions. And it's why AF is not guaranteed to work if you do anything to throw away light, like add a teleconverter behind your lens.

In the process of replacing and rebuilding the mirror box, I had to remove the AF sensor assembly and transfer it to the new box.

This may require the position of the AF sensor to be adjusted.

Obviously, the ability of the lens to precisely focus on the sensor is critical. And the ability of the autofocus sensor to choose the
right position for the lens, to focus correctly on the sensor, is also critical. But it is possible for the AF sensor to be positioned incorrectly, so IT sees good focus, but that good focus isn't right for the main sensor.

I expect to have to adjust the AF sensor position when this repair is completed.

Fortunately, it's not that difficult to do it.

On the bottom of the camera, there's the DC power board. There are two holes in it. Deep inside those holes are two adjustment screws. They adjust the vertical, up/down position of the AF sensor in the mirror box. I can adjust both side of the sensor's height in the mirror box using those screws. The trick is to use live view, and preferably, hook the HDMI port up to a computer monitor when doing this procedure. Focus on a focusing target, manually, then activate AF, and if it doesn't focus correctly, make a small adjustment to the height adjustment screws, and try again. Adjust each side screw separately to get AF working properly on both sides of the field of view. I would use the leftmost and rightmost focus points for this adjustment. Just be sure that the focusing target is bracketed within the specific AF point window that you are working with. Remember you'll have to press the shutter release button to the first position (AF activate) after every adjustment.

Unfortunately, you can't have the camera solidly mounted to a tripod when making this adjustment for the simple reason that the bottom plate has to be off. So I'll have to figure something out. I suspect I'll just buy another bottom plate off ebay and drill it out to access the AF adjusters, and use that when doing the adjustments. Make it a test fixture.

At this point I have reassembled the camera, once, and found that it was mostly working. I have taken pictures with it, and generally, they've been good pictures.

But I found that I was getting lens errors at higher F stop numbers. It turned out that the aperture actuator lever mechanism had also been damaged. If you take the lens off your camera and press the preview button, you'll see the aperture lever snap down and then snap back up when you release it. This controls the aperture position and does it every time you take a picture. On this damaged mechanism, it could not go down beyond the f/5.6 setting. So I've ordered a replacement mechanism, which should be here in a few days.

The last issue i'm addressing is the replacement of the connector, on the main PC board, that the LCD display connects to. This is a tricky job, as not many people can successfully replace a surface mounted, 61 pin flex connector with a connector pin spacing of just 0.3 millimeters between contacts. I can. I've been doing electronics repair for 35 years. But I've entrusted this particular job to a friend of mine who is even more experienced at this particular sort of work, and has better equipment for it, than I do.

If all goes well I'll be reassembling the D810 in a few days, after which I'll subject it to a variety of tests, realign it as needed and as i am able. and put it into service as my new main camera.

In truth, I enjoy the process of fixing cameras as much as I enjoy getting a memory card full of great pictures.
 

D200freak

Senior Member
While it is complex, it's engineered such that it's really not that difficult to work on it. The most complex mechanisms are assemblies that are intended to be replaced as units rather than repaired at the level of the individual part.

There are basically three mechanical systems in the D810: The shutter system, the mirror control system, and the aperture control system.

The shutter system is by itself in the back frame.

The mirror control system and the aperture control system are both controlled by a single mechanical package that's part of the mirror box. A problem with either would generally require you to replace the single mechanism that controls both.

There is also a simple mechanism for the autofocus unit, but again, in the event of a problem you'd most likely replace the complete AF assembly.
 

WayneF

Senior Member
I thought this was a very interesting comment:

What you may not realize is that the main mirror is semi-transparent. SOME light passes through it, and that light is directed, via a SECOND mirror, downward to the autofocus sensor assembly.


To my knowledge, Nikon never acknowledges this design. I get the idea they imply autofocus and exposure is in the viewfinder, but of course, if we look with the mirror up, we can see the sensors in the floor.

Other sources describe this, like
How Phase Detection Autofocus Works
or
Everything you always wanted to know about the semi-transparent mirror technology (but were afraid to ask) - Good and bad sides of conventional mirrors - LensTip.com

But to my knowledge, Nikon never mentions it.


 
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AC016

Senior Member
I am quite surprised that the front face plate is plastic, not to mention the structure under the lens mount. I would have thought we would see more metal here. Anyhow, good luck. It will be great to see some photos from it.
 

D200freak

Senior Member
The D800 has both a magnesium alloy back frame and front frame.

To save weight, the D810's front frame was changed to plastic. Probably reduces cost as well.

I do not think that a D800's magnesium front frame can be retrofitted to a D810. Too much is different.

Though the D800 and D810 are very similar, NOTHING about them is the same. Parts don't interchange. I'm sure Nikon did this to ensure that nobody would be able to dress up a D800 as a D810 and pass it off as such to an unsuspecting buyer.
 

Danno

Well-known member
Contributor
Anxious to see how things progress. Glad you are on your own thread. It makes it much easier to find. That kind of work you are doing takes a steady hand. Very cool.
 

D200freak

Senior Member
I also repair mechanical wristwatches, but on a very limited basis.

I'm comfortable with anything electronic or mechanical, from rebuilding V8 engines to repairing wristwatches, from heavy equipment power generation and distribution systems to repair of modern microelectronics.

Life is an ocean of knowledge. Dive in. You will not drown.
 

Danno

Well-known member
Contributor
I was going to ask if you fixed watches. I rebuilt car motors and motorcycle engines.... but stroke took that stuff away.

Sent from my SM-T530NU using Tapatalk
 

D200freak

Senior Member
LIMITED watch repair. I won't make the larger investment required to be well equipped for watch repair. But I admit, I kind of LIKE working under a stereo zoom microscope.
 

D200freak

Senior Member
I got the broken flex connector replaced on the main board, which is what the display connects thru.

I have reassembled it and at this point everything seems to be working.

I will need to perform an autofocus calibration but that's actually pretty easy when you understand how to do it. Which I outlined previously. In simplest terms, calibrating autofocus is a matter of adjusting the AF sensor's image plane to be exactly as far away from the lens mount as the imaging sensor is, as measured by the path that the light travels. Then minor tweaks are made in the AF fine tune menu.
 

Danno

Well-known member
Contributor
I got the broken flex connector replaced on the main board, which is what the display connects thru.

I have reassembled it and at this point everything seems to be working.

I will need to perform an autofocus calibration but that's actually pretty easy when you understand how to do it. Which I outlined previously. In simplest terms, calibrating autofocus is a matter of adjusting the AF sensor's image plane to be exactly as far away from the lens mount as the imaging sensor is, as measured by the path that the light travels. Then minor tweaks are made in the AF fine tune menu.
Sounds pretty cool. Looking forward to seeing pictures of the repaired camera and from the repaired camera.

Sent from my SM-T530NU using Tapatalk
 

D200freak

Senior Member
i will be going back into it one more time to replace the aperture control unit, because while it seems to be working right now, it's not reliable and probably has something damaged in it. At that time I'll also do the AF calibration. I'll be sure to post photos of the work, and then, photos made by the camera.
 

rocketman122

Senior Member
BRAVO BUDDY! just amazing! I salute you for taking such a complicated task. just curious, do you know if theres a technicians software version anywhere one can get? wanna fix a reoccurring back focus issue with my D3? it keeps coming back every 6months or so. I pay, they rest the system, 6 months later it acts up. it will shoot and then here and there will no lock focus. so have to put it in manual mode fire a shot or to and it will work again. till the next time it has a fit.
 

D200freak

Senior Member
I haven't found any such software yet. But I do look for it.

SOMEWHERE, I'm sure there's somebody who would be able to get his hands on Nikon's own service software for testing and aligning various camera. I hope to make friends with that person when I am able to do so.
 

D200freak

Senior Member
There's really nothing to photograph tonight so I printed up a focus test chart and started testing. Focus is as good as I can determine (at close range) with that test chart, so I went outside to try to see how tight it focuses on bright stars. Result: Not quite as sharp as my D800, which means some more adjustments are needed. But it gets close enough that I know that everything is working normally. Manually I am able to focus to an incredibly sharp image, just barely. It's rather sensitive, as you might imagine. So a few little tweaks and I should be on it.

Interestingly, the aperture control error hasn't resurfaced today. I'd be perfectly happy to NOT need to replace it but the replacement unit will still be here later this week. I won't mind having a spare unit.
 

Ruidoso Bill

Senior Member
All I can say is Wow! You are so far ahead of me I can't believe it. You will love the D810, I have both the D800 & D810 and I am just not racking up many shutter actuations on the D800, I love the D810, it feels better, makes less noise and is in my opinion one of the best bodies Nikon ever has made. I am so excited you have resurrected such a great camera. Also, if I break mine would you be willing to fix it, just hoping incase I do something stupid that my insurance doesn't cover, or I buy another and trade in the D800.

You are one amazing dude!
 

D200freak

Senior Member
Actually the D800 is a sturdier body than the D810. The D800 has magnesium alloy front AND rear frames, while the front frame on the D810 is plastic.

If you need repair services, I'm always willing to consider taking on the work. But I am not a professional, Nikon factory trained camera tech. I just have the background to be able to adapt to camera repair work pretty easily.

I am quite pleased to now have two FX bodies to work with. I guess now my only real remaining use for my D200 is for product photography for ebay. So I should sell off at least one of my D200s now. Probably the minty one with box, manuals, chargers, etc...

I don't expect to stop using my D800. But will I have done so six months from now? I don't know.

For now the 810 is not yet declared a total victory. It needs considerable testing and maybe a few more adjustments before I certify it ready for deployment. Everything has to be checked, all ranges and combinations of aperture, shutter speed, and ISO. Connectors and functions checked. Plenty to do.
 
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