Nikon DP-20 (for F4): Fall from 2.75 m height, LEDs shifted

[Andreas Thaler]

The day had to come when I would cause my own repairs

Today, while I was rearranging my cupboard, a DP-20 viewfinder for the F4 fell from a height of 2.75 metres onto the parquet floor.

The viewfinder is intact on the outside, the glass inside is OK and the LCD works.

However, the LED displays have slipped up a bit:

The top left LCD is OK, I just couldn't get it all in the picture.

Good thing I've already worked with the DP-20.

This needs to be repaired immediately!

 

[Andreas Thaler]

Since the LEDs are located in the Nikon F4, which didn't crash, the problem will be in the viewfinder mirror system.

Thank goodness it's my spare DP-20, which isn't the prettiest anymore, but has an intact LCD to replace.

 

[Andreas Thaler]

Repair

Removing the outer cover and loosening the inner cover.

The DP-20 has two covers that protect its interior. For details on disassembly see

Nikon DP-20 viewfinder (for Nikon F4): LCD examined, case disassembled and reassembled

After replacing the top LCD in the viewfinder of a Nikon F4, I wanted to know what the procedure is for the bottom LCD. To do this, I dismantled a functional DP-20, the standard viewfinder for the F4, whose display is badly bleeding. It has black and green spots that partially cover the...

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This should be cleaned later.

This is where the three deflection mirrors for the upper viewfinder displays are located.

From top to bottom:

• LCD with exposure compensation and frame rate display,
• ADR (Aperture direct readout) for reflecting the aperture number on the lens, and
• the LEDs for AF, exposure compensation warning and flash readiness.

All of these displays are located in the F4 housing and are reflected in the DP-20.

The mirrors are mounted on metal springs.

The metal springs press the mirrors against these adjusting screws.

Here you can see that the upper and lower mirrors are not in contact with the adjusting screws.

The misalignment was caused by the fall.

I unscrew the two adjusting screws for the lower mirror …

… and move the mirror on its metal spring towards the adjusting screws.

To do this, I take the blade of a flathead screwdriver and carefully press on the metal spring.

Now I can adjust the mirror against spring pressure using the screws.

First attempt.

The red LEDs are now too low.

The LCD on the left needs to be corrected downwards.

The reference is the ADR display in the middle. Its mirror was not misaligned by the impact because it is still pressed against its adjusting screws.

After I have adjusted the mirror for the LCD by bending its spring, I adjust it and the mirror for the LEDs using the screws.

After a few attempts, the positions are correct.

The outer cover is always in the way because it is connected to the viewfinder by wires.

In this position it is not in the way when doing this work.

 

[mshchem]

Oh no! Good thing you have repair skills. I'm always fearful that I will smash something. I remember dropping my one and only camera, Pentax SP 500, when I was a kid. That made me a believer in a protective filter for the lens. No harm once I replaced the filter.
Please post your progress

 

[mshchem]

Repair

View attachment 376816

Removing the outer cover and loosening the inner cover.

The DP-20 has two covers that protect its interior. For details on disassembly see

Nikon DP-20 viewfinder (for Nikon F4): LCD examined, case disassembled and reassembled

After replacing the top LCD in the viewfinder of a Nikon F4, I wanted to know what the procedure is for the bottom LCD. To do this, I dismantled a functional DP-20, the standard viewfinder for the F4, whose display is badly bleeding. It has black and green spots that partially cover the...

www.photrio.com

View attachment 376807

This should be cleaned later.


View attachment 376814

This is where the three deflection mirrors for the upper viewfinder displays are located.

From top to bottom:

• LCD with exposure compensation and frame rate display,
• ADR (Aperture direct readout) for reflecting the aperture number on the lens, and
• the LEDs for AF, exposure compensation warning and flash readiness.

All of these displays are located in the F4 housing and are reflected in the DP-20.


View attachment 376809

The mirrors are mounted on metal springs.


View attachment 376811

The metal springs press the mirrors against these adjusting screws.


View attachment 376814

Here you can see that the upper and lower mirrors are not in contact with the adjusting screws.

The misalignment was caused by the fall.


View attachment 376808

I unscrew the two adjusting screws for the lower mirror …


View attachment 376805

… and press the mirror towards the adjusting screws.


View attachment 376815

Now I can adjust the mirror against spring pressure using the screws.

First attempt.


View attachment 376812

The red LEDs are now too low.

The LCD on the left needs to be corrected downwards.

The reference is the ADR display in the middle. Its mirror was not misaligned by the fall because it is still pressed against its adjusting screws.


View attachment 376804

View attachment 376817

After I have adjusted the mirror for the LCD by bending its spring, I adjust it and the mirror for the LEDs using the screws.

After a few attempts, the positions are correct.


View attachment 376806

View attachment 376818

The outer cover is always in the way because it is connected to the viewfinder by wires.

In this position it is not in the way when doing this work.

Beautiful!

 

[Andreas Thaler]

In order to be able to check the adjustment of the mirrors, the DP-20 must be set to the F4.

To do this, simply put the outer cover on without screws.

The buttons for diopter correction and measuring mode and their cover caps ready for installation.

The DP-20 is tested on the F4, everything works

Actually, this DP-20 is too good to be used as a spare parts warehouse (LCD) because it works. The abrasion on its cover gives it charm.

I think it's impossible to pry the two soft plastic caps off the buttons made of the same material without leaving marks.

They are attached with some Pliobond.

But since I don't have any spare parts, unlike Nikon Service, that shouldn't bother me any further.

---

Conclusion

• The DP-20 is robust.
• You can see that it can withstand a heavy impact without significant damage.
• In this case, repair is easy, the viewfinder does not have to be disassembled further to adjust the mirrors.

+++

All information provided without guarantee and use at your own risk.

 

[Andreas Thaler]

Oh no! Good thing you have repair skills. I'm always fearful that I will smash something. I remember dropping my one and only camera, Pentax SP 500, when I was a kid. That made me a believer in a protective filter for the lens. No harm once I replaced the filter.
Please post your progress

After this mishap, the day was actually ruined for me, and I find it hard to forgive myself for something like that I love my photography stuff.

But since it immediately became a repair project and everything turned out well, I'm back in balance.

 

[Andreas Thaler]

Beautiful!

This project wasn't planned, I actually wanted to do something else. But I couldn't put it off.

 

[benderscameracorner]

Conclusion - the F4 is every bit as solid and durable as it feels in the hand!

 

[Andreas Thaler]

Conclusion - the F4 is every bit as solid and durable as it feels in the hand!

Definitely!

But if the DP-20 had crashed on the F4 and had to absorb the total weight, things would probably have turned out differently …

 

[Andreas Thaler]

I'll test the DP-20 on the F4 against a second one to see if I notice anything else. But so far it looks good.

The LCD (seen in the viewfinder of the F4 on the bottom) has a bleed on the right that wasn't visible a few months ago. This may have happened because of the impact.

The AF system shouldn't be affected by the crash because it's completely in the F4.

 

[Andreas Thaler]

Quick test

I compared the DP-20 that fell to the ground with a second DP-20.

The F4 is on a tripod aimed at a bright part of the darkened window.

Aperture priority mode, ASA number and aperture constant.

Identical shutter speeds are displayed for both DP-20s in the exposure modes Matrix, Spot and Selective.

This means the test has been passed

By the way, this is the F4 that I opened in April this year and cleaned and oiled the aperture control (the common problem of a lame aperture on the F4):

Nikon F4: Mission Aperture Lever - two ways to fix the aperture problem

{Moderator note 12 Jan 25: five threads on the F4/F4S aperture lever repair have been merged into the present thread. You may encounter one or two dead links to 'other' threads. The posts they pointed to, are now all part of this thread, which mostly still follows the journey in a logical and...

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The aperture still works perfectly.

AF and exposure metering (spot metering) also work without the viewfinder attached.

In manual exposure mode, the upper LCD shows the exposure adjustment +/- on the left and the set shutter speed on the right.