XA Wonky Light Meter

sooner

sooner

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Hi Folks,

I paid $60 for an Oly XA supposedly in excellent condition from a member of this board. After arriving in short order and very well packed, I found the light meter off, under-exposing by like three stops. Yeah, like at 100 iso in bright sunlight with aperture of 2.8 it sets the shutter at 1/15th of a second. In anything less than full sunlight, we're down in the 1/8th or slower range.

I contacted the seller but he assured me it was working great when it left, and I really hesitate to conclude that he unloaded a defective camera on me, even though I feel disappointed if not a little ripped off. I had wanted this thing for slides, but even print film won't work this far off the mark.

Anyway, my question to you all is simply this: any chance of fixing this myself, or would any of you like this camera with the stated defect? Keep in mind I am currently in France and shipping would be expensive unless in Europe.

Thanks for indulging me......John.
 
The light meter did this with the batteries that came with the camera, so I changed them out with some here in France. I asked for some with the same voltage and got a pair the same size with "Renata 357...Swiss Made" on them. But if they are the right voltage, why would that throw off the meter? I really don't understand the subtleties of batteries, and would love for this to be the problem.
 
I only have xa2, but I think the mecanism for masking the photocell is similar on the XA. Look through the little meter lens and see if you can tell if the steel mask is moving when you move the asa lever from one extreme to the other.
I have an xa2 that had the steel mask fall off of the actuator, I believe in shipping. The thing I'm calling 'steel mask' is a cresent shaped piece of stainless steel that has tiny holes for the slow setting and progresses to big holes for the high asa and is between the cell lens and the cds cell.
On my Xa2 I can see the mask as a silver reflection from the meter lens when on the slow film speed extreme, and on the fast film extreme, I can just make out the orange and squiggly cell structure.

If that's come unattached from the selector lever, it's easy enough to fix, but it does involve surgery.
Later---- i add:
I looked at some pictures of an XA- seems the XA has a comparitively huge meter window above the lens compared to the teeny almost round one on the XA2, so it may be easier to see the hopeful movement of the mask.
 
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Clintock, thanks for the suggestion. I checked my XA and you're right, there's a relatively large band that moves as the asa is changed. I don't see anything loose or missing there. I see the silver band but no cell, everything seems to be in place. Oh well.

Also, I confirmed that the 357 batteries I bought were the correct ones, so it's not the batteries.

I guess it comes to this: what could have happened in transit to give me a fairly consistent three stop (plus?) overexposure, and how to fix it?
 
There's a downloadable repair manual on this page:
http://www.kyphoto.com/classics/repairmanuals.html
note you have to enter the password etc, but the password is on that page, it's just there to prevent outside linking. The manual is free to humans.
When some of my om2 act up, I found turning the switch on and off a couple dozen times straightnens them up sometimes.. In the XA the switch is activated by the clamshell cover.. But to be consistently off is odd..
Sorta like the backlight switch is stuck on or some switched contact to do with the flash may be not making or stuck..
 
Sooner: The issue with batteries is very briefly summarized as follows:

The silver-oxide SR44W/357-303 and true equivalents have discharge characteristics wherein the voltage remains stable until the battery dies.

So as alkalines age, the voltage gradually drops and you don't know that exposure is off. Battery check still works, so you think you're fine.

Some cameras have meter circuits that compensate for this, but the XA and many older cameras are not among those.

Some silver oxide batteries don't have the same discharge curve as the high-drain SR442/357-303, their curves look a bit more like the alkalines. Hence the need for that specific type I mentioned.

Since you got the correct type to replace the originals, it appears batteries are not the issue, but it's always the first place to look, as it's an easy and cheap check.

Roland's question about actual exposure (your initial post doesn't state whether your observations are from the meter display or negatives) is a good one. I've noticed with the XA that the meter display doesn't seem right, but the results are fine. Three stops off in the display is a bit much, but it's still a good question.

Not long ago I got an XA back from CLA from John at Camtech. I could have sworn the meter was off, but the exposures proved me otherwise.
 
I think the last 2 posts are on the right track.
I recall reading somewhere that the XA has 2 circuits - one for the meter and one for the shutter. So the meter can be off and the actual exposure OK. Can anyone confirm this?

Dean
 
Dean said:
I think the last 2 posts are on the right track.
I recall reading somewhere that the XA has 2 circuits - one for the meter and one for the shutter. So the meter can be off and the actual exposure OK. Can anyone confirm this?

Dean
Click to expand...

I think that's correct, like for the OM2.

Roland.
 
I looked at the schematic and it does appear the meter and the shutter control circuit are independent- the meter even has it's own cell, there are two cds cells!
It looks like there is a trim potentiometer to adjust once the covers are off..

So it is quite possible, you could both be right- the seller right it made photos just fine, and it still indicates off..
 
The cells are next to each other, I guess that's why the cell window above the main lens is so wide on the XA. The best reason I can think of is that somehow the circuit wound up simpler and more reliable that way, based on what they had when the camera was designed. The meter and the shutter I suppose needed independent adjusters, since the thing is all analog, and maybe this method isolated the two circuits so one adjustment would not effect the other.
It's hard to tell, but maybe the cds cell in the meter drive circuit has a harder life with more current through, thus has drifted more over time than the shutter control one which only I think supplies a voltage to the input of a comparator or something low current like that.
 
Thanks for all the tips. Before attempting a self repair, I may just shoot a test roll to see if indeed the problem is a faulty viewfinder but correct exposures. When I move the asa from 25 to 800 pointed into the same light, the viewfinder shows a logical change in shutter speed. But it's still too slow. This morning, I pointed the camera into bright sun at 100 asa and f/16, hoping to see 1/125th or even faster, and it showed 1/30. And actually it should have been more because this was right into the sun.

I should also clarify that I do not believe I got ripped off. In my first post, I should have stated that I was disappointed and felt ripped off but in a way like "why me." Anyway, I will update this after shooting a test roll to let you know how they turned out, but it will be a week or two because I can't develop my own film here. Thanks again.
 
clintock said:
The cells are next to each other, I guess that's why the cell window above the main lens is so wide on the XA. The best reason I can think of is that somehow the circuit wound up simpler and more reliable that way, based on what they had when the camera was designed. The meter and the shutter I suppose needed independent adjusters, since the thing is all analog, and maybe this method isolated the two circuits so one adjustment would not effect the other.
It's hard to tell, but maybe the cds cell in the meter drive circuit has a harder life with more current through, thus has drifted more over time than the shutter control one which only I think supplies a voltage to the input of a comparator or something low current like that.
Click to expand...

Is one cell measuring OTF and the other off the lens, maybe ? And like you said, it might have been easier from the engineering standpoint since you need two circuits (one to drive the needle, another to charge a capacitor to close the shutter). Also, maybe some possible reuse from the OM2 ?

Roland.
 
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