# Camera Repair - Learning and specific light meter question



## ApSciPhoto (Dec 9, 2011)

I teach film photography at a high school, and we blow through cameras. We get so many donated to us and a few years ago we bought a whole new set, but out of 60+ students we probably only have about 20 working cameras.

To avoid mounting repair/shipping costs (since no one in the area seems to repair them anymore) - how on earth do people learn how to fix them? I'd really love to have a more active working knowledge of how all the parts work together. Is it just pulling them apart and fiddling around?

For more immediate repair, I have one camera - a Promaster 2500 PK Super - that the light meter is always on overexpose.  No matter what. I tried changing the batteries, to no avail.  Suggestions?


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## DannyD (Dec 27, 2011)

I teach photography in a High School in Belgium ! Nice to meet a collegue ! 

Keep in mind that basic cameras from the 1960's and some other cameras don't require rocket science to understand how their light-meter works. It's just a matter of Ohm's law and voltage dividers. For example, a Minolta SRT-101 is made to use a mercury battery (1.35v) while actual batteries are alkalines (1.5v). To make these cameras working good, a meter calibration is necessary. It's pretty easy. On such cameras, you have to remove the bottom plate to see two trim pots. One pot is used for the battery check and the other one is for the light metering. 

A simple method is to take the measurement on a plain wall (a grey wall is the best) and compare with a working camera. Then, you simply adjust the metering pot to match the good camera's exposure. 

The promaster camera you're talking about looks the same as my Vivitar V3800n. My camera is overexposing too, but not dramatically. When my Canon says 1/125 f:13, the Vivitar says 1/125 f:11 which is not a problem for exposing films. 

What do you mean by "the light meter is always on overexpose" ? Is the red + sign on the finder always on ? Maybe there is a bad contact somewhere. Most of the time, electronics problems are about bad contacts. It's not rocket science neither, but it requires some skills to spare the camera. You have to remove the top cover carefully and clean the contacts. Use a drop of deoxit a q-Tip to do this. It's the first step to check this out.


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## compur (Dec 27, 2011)

ApSciPhoto said:


> To avoid mounting repair/shipping costs (since no one in the area seems to repair them anymore) - how on earth do people learn how to fix them? I'd really love to have a more active working knowledge of how all the parts work together. Is it just pulling them apart and fiddling around?



There used to be camera repair trade schools but they are gone now AFAIK.  

Camera repair books by Thomas Tomosy and Ed Romney are still around (though out of print mostly) and a good place to start.  There are also tons of individual camera repair manuals published by the manufacturers for use by their repair technicians and some monthly camera repair trade magazines that can occasionally be found in places like eBay. And, of course, many repair references for specific cameras can be found on the net as well.

Film camera construction is surprisingly complex and I suggest starting with simple cameras and ones you don't might sacrificing for learning sake in the beginning.  Some repairs can be easy but some can be mind-bogglingly difficult.  There are some cameras that, even back in the day, many pro camera techs would refuse to touch.

One place for repair tools and supplies is www.micro-tools.com


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