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kras 3 light meters not working


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#1 Richard Tuohy

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Posted 09 November 2009 - 06:11 PM

hello all,
richard tuohy in Australia here. I was teaching the first two days of a 4 day 16mm film shooting course on the weekend. Two of the students brought in Kras 3 cameras they had recently purchased from the Ukraine (as you do). I also had a k3 there. The light meter works fine on my k3, but the meters failed to work on both the student owned k3 cameras (using my battery insert and battery). Has anyone had simmilar problems to this? Does anyone know if there is a typical fault that can be remedied here? Is it likely the meters are broken, or is there possibly just a wire or bad solder somewhere?
Any suggestions before I volunteer to open their cameras myself would be appreciated.
cheers,
richard
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#2 Ian Cooper

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Posted 09 November 2009 - 06:17 PM

Sorry in advance if it's a stupidly obvious suggestion I'm about to make: But are the light meters on the 'faulty' cameras actually turned on?

I seem to remember the location of the on/off switch in the centre of the speed dial isn't particularly obvious in the first place, and even then isn't the easiest dial to turn either.
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#3 Richard Tuohy

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Posted 09 November 2009 - 10:21 PM

Yes that is a valid point Ian! But yes, I was turning the meter rotary dial switchy thing on when I was checking them. I did have my k3 there as a reference and while it was working, the same battery and battery insert used in mine and put in their cameras didn't yield a result.
rt
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#4 Ian Cooper

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Posted 10 November 2009 - 02:40 AM

Yes that is a valid point Ian! But yes, I was turning the meter rotary dial switchy thing on when I was checking them. I did have my k3 there as a reference and while it was working, the same battery and battery insert used in mine and put in their cameras didn't yield a result.
rt


Oh well, never mind. I realise people suggesting "...have you turned it on?" when you have something not working can be a pain in the rear!

I don't know if you've had the inside chamber plate out on a K3 before? It's nothing to be afraid of - all pretty straight forward, you just need to watch out for the ratchel pawls! ;) With that out of the way you can access the wires on the back of the battery holder and the wiring up to the on/off switch. You are in the area of the meter needle bit as well, but I can't remember how accessible the electrical connections are. The actual sensor cell is hidden elsewhere - presumably round by the prism at the front of the camera.

Armed with a test meter hopefully you can track the voltage around the film chamber half and just find a broken wire or loose solder joint. I never even put a battery in my K3 to see if the meter worked, so I can't speak too much from experience of the light meter circtuit, sorry.



Edit: If you've not been in there before, the k3camera website has some useful info on removing and replacing the film chamber plate.

Edited by Ian Cooper, 10 November 2009 - 02:43 AM.

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#5 Olex Kalynychenko

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Posted 11 November 2009 - 03:24 AM

Yes that is a valid point Ian! But yes, I was turning the meter rotary dial switchy thing on when I was checking them. I did have my k3 there as a reference and while it was working, the same battery and battery insert used in mine and put in their cameras didn't yield a result.
rt

The problem with light meter - is standar problem of K-3 cameras.
Krasnogorsk cameras have primitive circuit of light meter, this is :
photo resistor- on-off switch, ballast resistor, indicator, battery and mechanical system of load of speed of film by truns of indicator, by levers and disk with screws.
If you send me letter on my private email, i can send you circit, images and other.
The photo resistor lost of sensitivity at long time of storage.
The cameras made at 90 yeras and lost of sensitivity of photo resistor - natural functor.
What you can do:
1. to set two 1.5 v batteries inside of battery module of camera and to check - niddle will moving ? the photo resistor can read of any light ?
If the light meter will run, you can re-calibrate of speed film scale.

If the light meter give no sign of life, all other proceudure can be with open of mechnaism plate of camera, at camera repair lab.

If you open of mechnaism plate, you will need check of indicator , photo resistor - separately.
If the indicator - OK, photo resistor change of resistance at change of value of light, you need replace of ballast resistor on resistor with other value of resistance.

But, I must underline, the procedure of openning of mechnaism plate will ask of procedure of adjust of position of film rollers, cog's wheel and can be problem for begginers.
That's why, if i can choose, i prefer to use of external light meter, from idea to re-assemble of mechnaism of camera.

From other side, i must underline, original light meter of K-3 camera have low precision, have effect of "blindness" and can show you wrong result of measuring at 90% of cases.

The modern, high speed films ask of precision value of light measuring, and i recomed to use of external, modern light meter.
If you wish, i will glad to continue of this discuss at personal letters.
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