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Waynemel
Tinkerer
Username: Waynemel
Post Number: 151
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 11, 2012 - 08:09 pm: | 
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The meter is working, as is the battery test button, but the meter is reading 2 stops too high (shows f5.6 when it should be f2.8).
I have searched the archives and have found some information, but my question is:
If there is a poor connection or corrosion in the battery test switch/battery holder, would this cause the meter to read high?
I am asking because the screw holding the battery compartment is corroded and will be difficult to remove. If there is no chance that the corrosion is causing the mis-reading meter, then I will leave it in place and look for another solution.
I am using a 1.35 volt mercury battery. |
Mr_flibble
Tinkerer
Username: Mr_flibble
Post Number: 60
Registered: 10-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 12, 2012 - 11:30 am: |
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Are the openings in front of the cDs cell changing along with the aperture ring? It could be that the mask with the holes is misaligned. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 152
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 12, 2012 - 12:20 pm: |
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I checked that already, and the openings appear correct. |
Nickon51
Tinkerer
Username: Nickon51
Post Number: 153
Registered: 05-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 13, 2012 - 02:41 am: |
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That means that there is too much current being drawn by the meter. The higher the light level, the lower the cell resistance, higher circuit current drives the meter towards the high f/ numbers.
Could be caused by too much light falling on the cell, eg the masks that mr_flibble mentioned, or some leakage current across corroded contacts. Does the test button drive the meter to the red mark? Is the meter at zero when the cell is covered?
I would look at the test/normal switch. If there is enough corrosion in there it could cause leakage from the test contact to the normal contact. Corrosion of that switch is not uncommon.
Here's a cct that I traced out once.
The battery case mounting screw does not carry any current so corrosion on that would not have any effect. Unsolder the green wire and see if the meter reads more accurately. The only other item is the variable resistor up by the meter which sets the sensitivity, It could have been carelessly adjusted.
Good luck
Greg Nixon |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 153
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 13, 2012 - 07:26 am: |
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To answer your questions, the test button does drive the needle to the red mark, however, sometimes it jumps in the opposite direction. The meter does zero when the lens cap is on.
If corrosion in the switch is a possible problem, I will have to disassemble and clean it. The reason I mentioned the screw is just that it is so corroded, I can't remove it without drilling it out and re-tapping. I was hoping to avoid that.
Thanks for your help. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 154
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 14, 2012 - 03:25 pm: |
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Just an update in case someone else experiences a similar problem:
I removed the battery holder and cleaned the contacts and switch (they looked OK anyway). I also re-soldered the blue wire as it was looking a little dodgy. The problem with the meter still persisted.
I removed the front of the lens, with the CDS cell, and double checked the mechanism with the slit for adjusting the amount of light that is measured. It was fine.
Since the error in the meter was consistently 2 stops, I fashioned a simple neutral density filter for the CDS cell by cutting a small, round piece of developed B&W film negative (from the beginning of the roll, so it was a similar grey color to a polarizing filter) and pushing it securely into the CDS cell lens.
When I checked the meter after reassembly, the meter was now only about 1/2 a stop high. I adjusted the variable resistor to compensate.
The idea for the filter came from a Konica C35 Automatic that I have. With that camera, there is no way to adjust the meter, so at the factory, they must adjust the readings by adding little filters in front of the CDS. Perhaps the S2 also had a filter and it had been lost somehow? |
Br1078lum
Tinkerer
Username: Br1078lum
Post Number: 258
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 14, 2012 - 08:32 pm: |
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There is always that possibility. Maybe the last person to own it didn't think they were neccessary.
PF |
Nickon51
Tinkerer
Username: Nickon51
Post Number: 156
Registered: 05-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 14, 2012 - 09:21 pm: |
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Thats an odd one. I have 2 Auto S2's here but neither has and ND filter over the CDS cell.
An innovative fix. Well done.
GN |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 157
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 21, 2012 - 08:14 pm: |
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Ok, so I have solved the meter problem, but now the aperture does not seem to be working properly.
I have cleaned the blades thoroughly and they work in manual mode. However, they will not stop down more than f5.6 or so in auto, even when the meter reads f16.
Any ideas? |
