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Jd1
Tinkerer
Username: Jd1
Post Number: 1
Registered: 05-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 30, 2012 - 07:09 pm: | 
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Hello everyone,
This is my first post and first major attempt at camera repair.
I picked up an old Konica Auto S3, which was in decent physical condition except for the hot shoe being broken off. I took an old battery out of it and didn't see any corrosion in the battery chamber.
When I replaced it with a zinc cell, here's what happened. For a few hours, the meter would move, but would underexpose by many, many stops. Probably 5+. It would rarely read above f1.8 on ISO 800 @ 1/8th, sometimes going up to f4 if I pointed it at my monitor. Perhaps this new battery is a bit drained now a few days later, but now the needle barely moves at all. It moves a bit when the shutter is depressed halfway. I tested the battery voltage when I opened it and it was fine.
The meter circuit is extremely simple, right? I haven't ripped it apart yet, but from I understand it's just the CdS cell, two (?) resistors, the meter, and the wiring. So it has to be one of these things. From these symptoms (extreme underexposure) what is it most likely to be? I am hoping it's just the wiring but I'm worried about the CdS cell, since I hear this is somewhat irreplaceable.
Any thoughts on how I should diagnose this beautiful old camera, hopefully in the least invasive way possible? I am handy with soldering but I hope I don't have to completely tear it down, because this seems tricky.
Your thoughts and experience would be appreciated. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 182
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 31, 2012 - 05:20 am: |
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Sounds like it is the wiring. As the wiring corrodes, it is less conductive and could result in the symptoms you describe. If the CdS cell was dying, the needle would do the oppposite, it would read higher than it should. If you are looking for repair information, try searching for information on the C35 automatic, as I think they are very similar. |
Jd1
Tinkerer
Username: Jd1
Post Number: 2
Registered: 05-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 31, 2012 - 09:33 am: |
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That is good news I suppose. Should I just replace all the wires in one go? I wonder how deep into the camera I'll need to go, and how many specialized tools I'll need, since this is my first ever disassembly. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 183
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 31, 2012 - 12:30 pm: |
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The first thing I would do is check to make sure the battery contacts are clean. Use a little vinegar on a cotton swab and make sure they are nice and clean. Put the battery back in and try again. If things don't improve, remove the bottom of the camera. This is fairly straight forward. Check the wiring and connections at the battery terminals. If they look rough, you may be able to re-solder them and not have to replace any wires. I have found the terminals on the C35 to be very difficult to solder however, it just doesn't want to stick. The S3 may be the same.
As far as replacing the wires, it doesn't require many special tools, but you will need to tear the camera down a bit. The top will need to come off, the leatherette will need to be peeled away to reveal the lens board screws. The lens board and lens will need to come off. This will allow you to remove the old wires and feed the new ones back through. I think that would be the basic approach, although the last time I did this on a C35, I had already taken the lens apart, so I did not need to remove the lens board.
If you do a google search on the C35, you may be able to find some photos of the process or at least a disassembled camera. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 184
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 31, 2012 - 12:32 pm: |
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Just another point:
What ISO is the camera set to when you test the meter?
This may seem simple, but I don't want to assume... |
Jd1
Tinkerer
Username: Jd1
Post Number: 3
Registered: 05-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 31, 2012 - 04:34 pm: |
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Thanks for all the help thus far -- I'll try the project this weekend. I tested at ISO 800. Do you think it's possible that the broken off hotshoe could disrupt the metering? |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 185
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 31, 2012 - 05:03 pm: |
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No. |
Jd1
Tinkerer
Username: Jd1
Post Number: 4
Registered: 05-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 03, 2012 - 08:56 pm: |
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Aha, it was the battery holder contacts that were shorting out! I should have known, but I didn't have my meter with me to test the battery when it died.
After putting a shim between the contacts, it seems to meter quite decently. Thanks again for the help. |
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