Need help with repairing Nikon DP-1 Photomic light meter

etarbar

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Hello, sir. I'm Kelvin from Thailand.

This is my first post here. (I've gained a lot of great info from here for several months though)

I purchased from ebay a lovely set of Nikon F2 (7698847) , photomic dp-1 (625209) and Nikkor Ai 50mm f/1.4 (3797595). They looks great and works like a charm, except the light meter. It always suggest to use high speed shutter and small aperture even there is no light going through the lens.

May I trouble you and ask some advice as I tried to fix it?

With correct battery, the needle stay in the middle when check batt button is pressed.
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With lens cap on which block all light to get inside the lens, iso 200, shutter 1/125s, aperture 5.6, needle goes at about +1 over exposure.
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With lens cap off and I shine direct light into lens, same camera setting as above, needle goes further to over exposure side.
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I found pdf of "Nikon DP-1 meter adjustment and cleaning procedure
By Glen Walpert, May 1999" and I followed the guide. I took it apart and cleaned every contact part including resistor ring as best as I could and reassemble back. The error of the meter still the same.
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I separate the bottom half and found that I can adjust Cds bright trim to 70 ohm, but dark trim I can't make it over 140k ohm, the 200k resistor give about 150k ohm.
Both Cds cells give ohm that respond to bright light and low light but I forgot to note the figure.

Which part that caused this error?

I found on ebay "a brand new old stock Replacement Resister Ring for Nikon DP-1 finder. part number is 20FD11-H5"
Can this part fix this problem?

I've tried my best to get this legend F2 set to function properly as my best friend has seeking for this set for a long time. I ran a roll of film to test its function (using my Olympus Pen D3 that I fixed its dead meter by changing new wire as an external light meter). The result was great with proper exposure. Double exposure function and timer also works precisely.
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I hope that you can spare some knowledge and help me to overcome this issue.
Thank you in advance for your kindly support.
 
Sounds like an electrical problem.

Be sure you are mounting the lens correctly and note that capping the lens will NOT guarantee that no light reaches the meter cells. You must cap the eyepiece as well.
 
I did email to Stephen Gandy for advice and he kindly suggest me to post here.
Frankly, I can not afford to send it to any service due to delivery cost from my country to US or UK is very expensive that I can get a new working dp1.
 
Hello again. I received a kindly advise from Mr. Sover Wong that Cds cells have aged and need to be replaced. He offer me a new pair for $44 plus $10 for postage. Now the meter is working again and quite accurate. Working Cds should give 4 million ohm in dark and 100 ohm in bright.
Mine got only 400 ohm in dark and 100 ohm in bright.

As explained in Mr. Glen Walpert pdf
"The meter movement is centered when it has about 0.025 volts across it, at about 16 micro-amps."
3v from battery runs through Cds and ring resistor. If Cds are out, in dark condition it will not block volt as it should. Result in always high volt as in the bright condition from Cds pass next to resistor ring.
In my case the resistor ring is still functioning, so the meter gave a linear response when changing shutter speed and aperture value.

I hope this info can guide someone that has same issue as me to overcome the problem.
Thank you.
 
Hi there!

I know this is an old thread, but I am in the process of trying to repair a DP-11, very similar to the DP-1, light meter.
With the light meter assembled, testing the batt contacts for resistance, I get more ohm or less If I aproach my hand from the glass or let mor light in. It also varies if I rotate the speed selector and/or the apperture ring conection.
I would say all the circuit is in good order, except the needle driver (do not know the name of the part), can this happen?
Battery test is also dead, I get no readings never.
I opened the meter on its two halves, did a good job cleaning everything, but no changes...

Any hint on how to test the needle driver to see if this is the culprit? If it is, can I buy one somewhere?

Thanks in advance for all the possible help!

Sergio
 
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