Nikon N55/F55 DX Sensing Repair

[ic-racer]

My Nikon N55 was having intermittent DX sensing issues. This was hard to track down, because there is no indication of the ISO that is being sensed. The way I could tell is if I put an empty DX cassette in the camera, just before it flashes ERR, it will show the exposure for a fraction of a second. That exposure it shows is the exposure from the DX coding and, if the cassette is not 100 ISO, then the meter reading will be different than before you put the empty cartridge in the camera.

Otherwise, you will wind up a whole roll into the camera, only to find the DX code did not 'take.'

Of course I cleaned the contacts, etc.

 

[ic-racer]

I looked at the schematic for the camera, to see where the issue might be. There really is nothing between the DX sensors and the main CPU chip except some connections to a resistor bank.
At this point it is looking like a poor solder joint or loose connection.

Of note, one of the DX sensor fingers is used as a switch to let the camera know a cassette is in place.

 

[ic-racer]

According to the disassembly instructions, the DX connections are right under the front cover. The front cover comes off after removing the bottom.

Looks pretty simple, but the two screw that come from the back are hidden, and there are two screws that can only be seen if the flash is flipped up.

The cover over #124 is held on with what seems like 2 sided sticky tape. The point of an Exacto blade can lift it carefully. The goop was still sticky, and after the repair, it stuck back in place.

So there are serven screws total to remove. The two side panels don't have to come off, though I took them off, not knowing if they were trapping the front panel.

 

[ic-racer]

After the front came off, the solder joints were visible. I re-flowed solder on these 12 connections.

 

[ic-racer]

I re-flowed the solder on these seven also. These connect right to the sensors, so I bet this is where the issue was.

 

[ic-racer]

So, did it work? Of course it worked, otherwise, I would not have posted the thread

After the repair, I think it was that bottom finger that serves dual function of being a switch that was bad. Reason being that NO DX codes were sensed. That is different that if one or two sensing fingers were bad. In that case the DX would just be different than what is intended. In my case, it was as if the camera was not recognizing any cassette in the camera.

Did that bottom-most solder joint look different. Well, yes it did. In fact when I first examined it, it looked not to be soldered.

 

[ic-racer]

 

[ic-racer]

Repaired and ready to go.

 

[BradS]

Wow! Thanks for the very detailed write up.
How/where did you find schematics?

 

[ic-racer]

A PDF of the service manual is available on-line. I don't recall the link. If you need it I can email it. I usually locate the service manual of a camera before I buy it.
Like many here, I enjoy collecting film photography equipment. Some people only collect a certain brand. I try to only collect serviceable items, or at least items for which the service manual is available.

BTW: I used this N55 camera many years without the DX function by setting the Exposure Correction value to -2 with Hp5. Works fine like that except the Exposure Correction is cancelled in Manual mode, and I like Manual mode.

Also, to point out why I wanted to keep the camera in good repair. The N55 has some of the best autofocusing and exposure software and hardware of just about any film camera. This was one of the last 35mm SLRs made by Nikon and it had all the best electronics, even though it is a plastic camera with some limitations in advanced function.

 

[Sharktooth]

It's great that you're able to fix this electrical issue to keep your baby working,.

...... but has anyone discovered a "fix" for the butt-ugliness of these puppies?

 

[ic-racer]

I think they are cute.

 

[awty]

Great work.
I have two, fortunately you can adjust the exposure a couple of stops either way when you use blank cassettes.
Best valued camera you can get, light and compact, easy to operate one handed, has plenty of functions, the meter is the same as a F6, batteries last a long time and they are cheap. Both mine cost under $20.

 

[ic-racer]

The main reason I wanted the DX to work was for very rare times when using manual. In that case it only meters at 100 iso and exposure comp is bypassed. The matrix meter is so good, after using manual a few times, I have gone back to auto modes for just about everything.

 

[parlordice]

I have a question about my 55 - have any of you heard of the recall? Apparently lots of the bodies had issues with an autofocus sensor or something. Long story short, mine is in perfect working order except that it simply won't let me release the shutter in AF mode no matter what I try. It's heartbreaking to hear that it has some of the best AF, because apparently Nikon recalled the cameras and offered a repair but they no longer do.

Does that service manual say anything about the AF contact with the lens perhaps? Or an obvious point of failure?

 

[ic-racer]

Don't know about the recall, but it might de worthwhile looking for a cold solder joint.

 

[ic-racer]

I found the pictures for this thread.

Bottom removed. I believe there were 9 screws.

 

[ic-racer]

In addition to the two screws on the front of the camera and the two screws under the flash, there are 3 screws accessible from behind the camera to release the front plate.

 

[ic-racer]

The circuit board where the DX feeler connection is visible.

 

[ic-racer]

Cold solder joint visible.

 

[ic-racer]

After re-soldering all seven points.