Nikon DP-12 Service and Repair (Nikon F2AS)

ic-racer · Feb 10, 2025

I don't see much information on the Nikon DP-12 finder that comes with the Nikon F2AS, so I'll document my findings here.

My DP-12 initially seemed to work OK but likely the wiper just started pushing dirt around on the variable resistor (FRE), leading to erroneous indication of the LEDs.

In my case I had two issues.

1) The (-) light would come on and stay on when the shutter speed dial was past 1/125, no matter the lighting conditions.
2) The shutter speed numbers in the viewfinder were partially cut off in the viewfinder.
3) Deteriorating foam rubber.

First step was to remove the vinyl covering from the top and remove the top cover.

ic-racer · Feb 10, 2025

Likely the varialbe resistor element needs to be cleaned. This is called the "FRE." Occasionally these will go bad and will need to be replace. More likely, it just needs to be cleaned.

There is a piece of foam rubber covering the indicator LEDs. Remove that and replace it later with a new piece.

ic-racer · Feb 10, 2025

There is not any access to the FRE from inside the unit. So we will access it from the top. Remove the V-shaped LED light pipe.

ic-racer · Feb 10, 2025

It is a tight fit, but the end of a soft cleaning stick can reach the FRE. I used ethyl alcohol and DeOxit to clean it.

In my case cleaning the FRE solved the issue of the (-) light staying illuminated at shutter speeds greater than 1/125.

ic-racer · Feb 10, 2025

Fine tuning the light meter's response with a calibrated light source. The Nikon DP-12 service manual documents how to do the adjustment. Basically the front most trimmer outlined in yellow is the overall gain and the rear one adjusts the slope of the response. In my clase only a small tweak was needed.

I calibrated at EV5, 9 and 16. The manual asks for calibration at 0EV but who has a calibrated light source that dim?

BTW: don't adjust the trimmer at the very front (not circled).

ic-racer · Feb 10, 2025

Alignment of the shutter speed numbers in the viewfinder is the same as DP-2, DP-3 and DP-12. The adjustment is outlined in the service manual, but may not be entirely clear as to what to do.

There are two overlapping disks. One with teeth like a gear (#104) and the other with ridges and grooves (#107). They are not glued together and are touching only with friction.
The idea is to hold #107 stationary and tweak #104 one way or the other to align the numbers. A little trial and error is needed.

These are both very, very small. I used a 1mm screw driver and a needle tipped pickup. Unless the numers are way off, only a tiny nudge is needed.

ic-racer · Feb 10, 2025

I replaced two tiny strips of foam rubber here.

ic-racer · Feb 10, 2025

I replaced the foam here and on the other side.

ic-racer · Feb 10, 2025

All back together and working great!

Little know fact, when the AI lever is flipped up into the finder to use pre-AI lenses, a red filter moves over the f-stop indicator in the viewfinder, making the numbers red. Yes, normally one would not know this because pre-AI lenses don't have the little numbers. But, if you do flip the tab up, and mount an AI lens to use in Stop-Down meter mode, you will see the numbers are now red to indicate your AI lever is flipped up.

Another cool feature. When the viewfinder shutter is closed, the little red light on top becomes active and will illuminate when correct exposure is set. Otherwise, when the viewfinder shutter is open, the top light is a combinatyion battey check light and low-light shutter-speed illuminator. Too bad it does not also shine on the aperture ring.

Andreas Thaler · Feb 10, 2025

This is specialist work in mechanics and analog electronics, great!

mshchem · Feb 11, 2025

Specialist indeed! Well done!

Bearman · Feb 12, 2025

Competition for Solver Wong!? Nice work

ic-racer · Feb 12, 2025

Sover Wong, yes that is where I saw the illuminated F-stop scale modification!

Chuck1 · Feb 13, 2025

Any idea if the prism in a dp1 is the same as the de1?

ic-racer · Feb 13, 2025

Chuck1 said:
Any idea if the prism in a dp1 is the same as the de1?

Good question. Not sure, but I did see on Sover's site a DP-1 to kind of DE-1 conversion in metal. When I saw that I thought it might not be difficult to come up with a 3d printed cap for a failed DP-1 to make it more like the DE-1.

Nikon DP-12 Service and Repair (Nikon F2AS)

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