Nikon F2 and DP-1 Photomic Meter Repair

[ic-racer]

I picked up three Nikon F2 from some on-line auctions. I put bids on just about every F2 I saw and wound up winning 3 at reasonable prices.

The most ratty looking is this 1974 F2 with DP-1 finder. The listing was 'parts camera.' I thought I could use the parts, but maybe the camera is functional.

Initial assessment:

DP-1 meter finder is dead
Rear cover is bent
Foam deteriorated
Shutter travel times and speeds off
Dirty optics, mirror and focus screen
Dent in shutter curtain

 

[ic-racer]

There is not much information on the internet, or in print, on galvanometer repair of the Nikon metered prisms, so I thought I'd share my experience.

The galvanometer can be removed with just two screws. The large geared potentiometer ring does not need to be reomved.
There is a screw near the center of the housing, and a threaded stud just peeking up behind the meter movement. There is a black wire that comes out of the meter movement and goes to the PC board. This wire needs to be de-soldered.

 

[ic-racer]

The needle in the Nikon DP-1 metered prism is controlled by a D'Arsonval galvanometer movement.

These meter movements are very fragile. The windings on the coil are thinner than a human hair. This one is actually suspended by the upper and lower spiral springs.

There is a plastic shroud (removed and not seen here). The two pieces shown here come apart with three screws. Be careful, the outer casing is magnetically attracted to the galvanometer and can rub against it, damaging it during removal.

 

[ic-racer]

I don't have a bellows unit for any camera, so the above image is the best I can show the movement.

Below is a cartoon of the device. The voltage is applied to the spiral spring. The center of the spiral spring is soldered to a small tab (not shown in the cartoon) around which the first wire of the coil is soldered. The coil wire then wraps around the armature where the other end connects to a similar tab and ultimately to the spiral spring and to the housing (ground).

So, from positive to negative there are about six connections that could be faulty.

I started with a careful inspection with a 25x loupe. A microscope would have been better.

I did not see anything obviously wrong. One of the wire-wound tabs could have been a cold solder joint. I did try to re-solder it but there was no change.

I poked around with a VOM and at one point I thought I saw the needle jump. Something had brought it intermittently to life!

I constructed a 4v power source from some dry batteries and tried to get it to move. There was some intermittent motion. Resistance was from 1 meg to 7k, with an occasional intermittent period of about 3 ohms.

I re-packaged the meter and connected it to the camera (the meter's batteries are in the camera body). It would intermittently register, but still was mostly dead.

 

[ic-racer]

The next day I tackled it again. There is no moving electrical connection like a brushed electrical motor, the energy for the moving coil is transmitted through the spring. However, I do know that intermittent electrical connections respond to DeOxit.

So, even though it did not make perfect sense, as a last ditch effort, I doused the mechanism with DeOxit.

To my surprise this actually worked!

 

[ic-racer]

Since I had fiddled with the meter movement a bit and wound up nearly destroying it on a few occasions, the needle was no longer resting in the correct position. Luckily I had an image beforehand that showed where the needle rest position was before I started the repair.

Then I had to decipher the adjustment screws. The smallest one (labeled "Centering") loosens and tightens the spiral springs, thus altering the free rest position of the needle.

The other two screws rotate eccentric bumpers that limit the maximum travel of the needle.

(none of this is in the service manual by the way).

 

[ic-racer]

After adjusting the meter needle position, the meter was calibrated (1.5v nominal silver cells) using the right-hand trim pot seen in the picture above.

The high and low trim pots ( inside the cutout on the left of the housing) did not need adjustment.

Inspection of the rotating potentiometer and wipers revealed them to be in good condition, in spite of the awful looking exterior appearance of this DP-1.

 

[ic-racer]

Below shows the camera after exterior cleaning. I still have to open it up for interior lube.

I did check the shutter and set the tensions anyway. With a 36mm travel, I got the shutters curtains to 9.5ms with 0.1 to 0.2 EV exposure error from start to finish.

1/2000 came out as 1/1650 and 1/1000 was 1/850. The others were also within limits.

 

[F4U]

Nice camera.

 

[Andreas Thaler]

@ic-racer

Impressive, thanks for the report.

Where did you acquire all this detailed knowledge?

 

[ic-racer]

@ic-racer

Impressive, thanks for the report.

Where did you acquire all this detailed knowledge?

I grew up in the pre-digital electric age! D'Arsonval galvanometers, panel meters, were everywhere--electrical and Hi-Fi equipment, appliances, automobiles, of course cameras, light meters and home-made equipment.

I made my first timer and light meter of my own design when I was 13. I took this picture of it in 1974 when I got my brand-new Zenit E; my first camera that would focus close without parallax error!! People take that for granted these days.

Yes there was a galvanometer in the Zenit -E too!

 

[ic-racer]

Nice camera.

Thanks. The other two F2 requiried much higher bids but are to be in much better condition. Or at least that is what I'm execting; they have not arrived yet.

This one is the most common F2 Photomic DP-1 and the other two are supposed to be equipped as DP-11 (F2S) and DP-12 (F2AS). The F2AS being the Holy Grail, with silicon blue cells, EV-4 sensitivity, CDS readout and AI meter coupling.

 

[Tel]

My go-to 35mm camera is my F2 with a micro-Nikkor 55 and a DE-1 finder. I can shoot anything that can’t outrun me and the batteries last forever!

 

[drboone]

ic-racer, do you have a recipe for dealing with the flaky contact of the resistor in the DP-1?

 

[F4U]

ic-racer, do you have a recipe for dealing with the flaky contact of the resistor in the DP-1?

a wee dab of deoxit is about all I would think can be done.

 

[Andreas Thaler]

I grew up in the pre-digital electric age! D'Arsonval galvanometers, panel meters, were everywhere--electrical and Hi-Fi equipment, appliances, automobiles, of course cameras, light meters and home-made equipment.

I made my first timer and light meter of my own design when I was 13. I took this picture of it in 1974 when I got my brand-new Zenit E; my first camera that would focus close without parallax error!! People take that for granted these days.

Yes there was a galvanometer in the Zenit -E too!

View attachment 389166

You compete Sover

Nikon F2 Repair/Overhaul Service

 

[Andreas Thaler]

ic-racer, do you have a recipe for dealing with the flaky contact of the resistor in the DP-1?

See

DP-1 ring resistors

 

[mshchem]

I grew up in the pre-digital electric age! D'Arsonval galvanometers, panel meters, were everywhere--electrical and Hi-Fi equipment, appliances, automobiles, of course cameras, light meters and home-made equipment.

I made my first timer and light meter of my own design when I was 13. I took this picture of it in 1974 when I got my brand-new Zenit E; my first camera that would focus close without parallax error!! People take that for granted these days.

Yes there was a galvanometer in the Zenit -E too!

View attachment 389166

Very Cool! Bell and Howell cine lens is a nice choice!

 

[ic-racer]

In terms of the ring resistors, so far the Photomic finders I have were saved by premature failure of another component.

 

[ic-racer]

a wee dab of deoxit is about all I would think can be done.

Yes

 

[ic-racer]

BTW, the DP-1 I have is a late model with the wire cladded ring resistor. So worth repairing, even it were to mean taking a galvanometer from an earlier unit with wonky resistor.

 

[ic-racer]

The beat-up DP-1 housing bothered me, so I went ahead and re-painted it.

 

[awty]

Very nice work.
Ive cleaned up a couple of those meters, I think they are pretty robust....as are the cameras. Cameras sound much better with a service and fixing the shutter ping.

 

[F4U]

Ya rurnt it! When I bought my F2 off ebay 15 or so years ago, I was specifically looking for an old beat up one that worked. So i could haul it around everywhere and use it without concern. I was disappointed wen it arrived. Absolute mint. Untouched. Virgin. And I'd be able to tell if it was a fix-up job. Now I can't go anywhere with it without treating it like a carton of eggs. Oh, well. Nice job though. Ain't it purdy?

 

[ic-racer]

There is a PDF out there titled:

Nikon DP-1 meter adjustment and cleaning procedure
By Glen Walpert, May 1999


It shows and tells much more than the service manual (which is basically an exploded parts catalog).

However, Glen has mislabled the trimmers for the HIGH and LOW EV range.

Correctly labled in this picture: