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03-29-2020, 01:15 PM   #1
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K1000 photocell circuit board swap out

Greetings, time to consult the hive mind...

One of my K1000's developed an issue with the photocell circuit board which I swapped out with one from a junk body which fixed the initial problem. However the light meter still over exposes and reaction seems to be less exagerated. I'm assuming that the two variable resistor need to be calibrated or matched up to the circuit that it's now in? Anyone ever done something similar or idea on where I go next, the service manual goes a bit sketchy...

Thanks in advance!

03-29-2020, 09:56 PM   #2
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I have done something similar with Konica C35. When it came the photocell was dead. The resistance was about 15 ohms and did not change with light. Since the camera was overall in a very good cosmetic condition I decided to give it second life. I bought a pack of various photoresistors of ebay, selected one with highest resistance in "normal room" lighting. Since the camera had no variable resistors for adjustment I added one in paralel (low EV adjustment) with the photoresistors and one in series (high EV adjustment).

Then I pointed the camera to a uniformly white wall. I used a tungsten lamp with variable intensity to simulate the lighting. Adjusted to max output, took the light reading with Canon EOS dSLR and adjusted the variable resistors to roughly match the reading. Then turned the lighting down and repeated the above. Then I repeated both to fine tune. The result was I got within 1/2 stop accuracy (to EOS metering) across the whole range of Konica camera - EV7 to EV19 if I remember well.
03-30-2020, 01:44 AM   #3
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QuoteOriginally posted by peter.d Quote
I have done something similar with Konica C35. When it came the photocell was dead. The resistance was about 15 ohms and did not change with light. Since the camera was overall in a very good cosmetic condition I decided to give it second life. I bought a pack of various photoresistors of ebay, selected one with highest resistance in "normal room" lighting. Since the camera had no variable resistors for adjustment I added one in paralel (low EV adjustment) with the photoresistors and one in series (high EV adjustment).

Then I pointed the camera to a uniformly white wall. I used a tungsten lamp with variable intensity to simulate the lighting. Adjusted to max output, took the light reading with Canon EOS dSLR and adjusted the variable resistors to roughly match the reading. Then turned the lighting down and repeated the above. Then I repeated both to fine tune. The result was I got within 1/2 stop accuracy (to EOS metering) across the whole range of Konica camera - EV7 to EV19 if I remember well.
QuoteOriginally posted by peter.d Quote

The result was I got within 1/2 stop accuracy (to EOS metering) across the whole range of Konica camera - EV7 to EV19 if I remember well.
Impressive results!!
03-30-2020, 02:44 AM   #4
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QuoteOriginally posted by Nuij Quote
Impressive results!!
Yes, I was quite surprised myself. I think I had a luck with the photoresistor selection. Every piece, even from the same batch, exhibits quite different curve.

03-30-2020, 06:17 AM   #5
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Looking from the back, the left variable resistor is bright light (EV15) and the right side is low light (EV9). EV15 is summer mid day brightness.
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