Konica Auto S2 meter

[Autcad24]

Hi, new to the forum. I have a Konica Auto S2 with an overly sensitive meter. I took the top plate off and didn’t see an obvious way to adjust. Checked the battery connections and no obvious corrosion. Any suggestions? Thanks!

 

[Duofold RF]

Do you put a 1.5V alkaline battery? If so the meter is designed for 1.35v mercury battery, you need to modify it by add a diode to decrease the voltage to 1.35V

 

[Autcad24]

Yep. 1.35 volt battery. It’s about 4-5 stops off. f4 in complete darkness, f16 in dim light

 

[Duofold RF]

So in total darkness (i.e. with the cap on) is the needle park at the 0 position? if not the Zero position needle to be adjust, or could be the cds cell issue

 

[Autcad24]

So in total darkness (i.e. with the cap on) is the needle park at the 0 position? if not the Zero position needle to be adjust.

Nope, it’s at F4. I don’t see how to adjust this meter.

 

[Duofold RF]

Check and clear the battery check button

 

[JeffS7444]

My Konica Auto S3 has a similar problem, and like your camera, there are no real adjustment points, just a couple of fixed resistors, and a galvanometer (which is best left alone unless it's become fouled with debris). I think it's safe to say that the CdS photocell is failing, and ought to be replaced. I'll be trying Advanced Photonix NSL-6110 as a replacement. Only reason I haven't already done this is that I'd like to order more than just a single small item, as companies like Digikey and Mouser have minimum shipping charges.

If this cell proves a bit too sensitive, I'll adjust with a tiny dab of paint, or adhere some light-reducing material to the front of the photocell. Wouldn't bother trying to do this with the existing part as it has deteriorated, and who knows whether you can get a properly logarithmic response from it.

 

[Autcad24]

So a selenium meter slowly dies and the meter no longer responds to light. A cds one gets wonky? Interesting. Then trial & error to replace. Very helpful info. Thanks!

 

[Duofold RF]

A failing CdS Sensor usually show decreased sensitivit rather than increased sensitivity. The circuit may have short in somewhere, need to clean check before replace the sensor

 

[Duofold RF]

When you remove the battery, where is the needle position? At zero or at f4?
If no battery the needle is at zero position but at F4 when the battery installed check circuit first before replace the Cds
If no battery the needle is at f4, adjust zero screw

 

[Duofold RF]

I had many Auto S2, I like the gold coated beamspliter and had salvaged many to use on my Leica III, it is much better than the original silver coated one.

 

[Autcad24]

A failing CdS Sensor usually show decreased sensitivit rather than increased sensitivity. The circuit may have short in somewhere, need to clean check before replace the sensor

A bad wire perhaps. Connections looked clean & sound under the top & bottom plates and front element. Stretching my skill sets to go much further. I’ve already bricked a Hi-matic 11 with my clumsy electrical work. The Konica is its replacement. Don’t need another display only camera!

 

[Duofold RF]

OK one way to try to use CRC Electronic Cleaner Spray clean the connection, battery compartment et al

 

[splitimageview]

I still have my S2 that I got when I was about 14, my first 'real' camera. I had to fix the meter a few years ago, it was wiring, battery compartment, and solder connections that had given up.

 

[Duofold RF]

Auto S2 - the first camera I overhauled and painted. Sold to a Japanese photographer many years ago

 

[JeffS7444]

A failing CdS Sensor usually show decreased sensitivit rather than increased sensitivity. The circuit may have short in somewhere, need to clean check before replace the sensor

Nevertheless, this is exactly what I observed with my S3, and the faulty CdS cell does indeed have very low resistance.

 

[Duofold RF]

Nevertheless, this is exactly what I observed with my S3, and the faulty CdS cell does indeed have very low resistance.

This is entirely possible, if the Cds shorted, there will be decreased / no resistance

 

[Autcad24]

I’m going to swap out the cell from the hi-matic I killed. I know that one worked. Hopefully narrow down the problem. But before then I’m going to go for a photo walk with my new digital light meter & the new (to me) Konica with some cheap Kentmere Pan 400. Thanks all for your advice!

 

[Autcad24]

Epilogue: I did find the meter adjustment for the Konica Auto S2 (attached picture) hidden under the rangefinder cover. Though it didn’t help for this camera maybe someone else will find this info useful.