Internal O Ring Replacement for Nikonos V

 In this blog post, I will show you, how I replaced the o rings of my Nikonos V. Besides replacing the internal o rings, I'll also provide the dimensions of the user-replaceable o rings.

First, remove the batteries

Four screws secure the cover of the electronics

Use some flat tool to hold against the screws, when unscrewing the LED exposure indicator cable

One screw in the film chamber …

… and two screws …

… at the take-up spool secure the inner part.

Remove the retainer clamp with a spudger or your fingernails

The removed retainer clamp

A reminder, of how to reassemble.

We find our first o ring here under the ISO dial. I call the position ISO dial bottom

There is another clamp on top of the ISO dial, underneath the winder. You can actually take it out more easily later after the rewind crank has been removed from the ISO dial.

There is a small hollow bar/pipe on the bottom of the rewind crank.

You can pull it out using pliers. I didn't have smaller ones handy, but would recommend a finder tool. What made it a lot easier, was holding both ends of the rewind crank, even the lower end, while pulling the pipe out, it reduced friction enormously 

On top of the ISO dial, underneath the clamp and washer, we find our second o-ring.

Don't be afraid, the next o-rings will be much easier to access

Unscrew the time setting dial (put it on M90 before). You might have to remove a small cap before, but many Cameras do not have them anymore anyway.

Just pull out the disc and the advance crank

Here, at the rewind crank, we find our third o ring …

… and number four:

The shutter speed dial o-ring.

Now we can lift out the inner part

If you are experienced in soldering you can desolder those four flash sync cables.

This makes it easier to work on the next steps, but it is not mandatory.

Another easy task is the door latch.

Here we find o-ring number five

Now we come to the shutter release, another quite easy task.

You can pull the release lever from the inside …

… while pushing from the outside.

Et voila, our sixth o-ring.

For regreasing the inner moving parts I used Molykote High Vacuum Grease. The supplier claims, that it supports the o rings' sealing ability – I don't know if this is really possible, but someone recommended it for underwater photo housings.

I did not replace the o-ring around the frame counter and the seals on the front and the back of the viewfinder. Those are very static and therefore should stay watertight rather long. If they become problematic I will add a replacement solution here. Or maybe someone reading this can share some information in the comments, I would be happy to update the article.

Please be aware, that I only confirmed these sizes through a first bath tube test, professional pressure testing is still pending.

Fix old cameras on YouTube (link will be added later) gave me some numbers for the o ring sizes and this is how I assigned them to my camera:

Internal measurement (mm)  - Thickness measurement (mm)  

2.4mm Internal - 1.9mm Thickness - doorknob – I am not quite happy with this choice, I think it could be a bit larger

9.92mm Internal - 2.62mm Thickness  – shutter speed dial 

4.2mm Internal - 1.9mm Thickness  – ISO dial top

9.25mm Internal - 1.78mm Thickness  - ISO dial bottom

2 each - 3.69mm Internal - 1.78mm Thickness – shutter release and advance lever

Also my own findings:

Battery: 15 x 1.9 mm 

Flash Sync: 9 x 2 mm (9.25 x 1.78 as well)

Door: 112 x 3 mm

Try to source NBR shore hardness 60, they should come very close to the original Nikonos o-rings.