Yashica Atoron (non-Electro) Repair (Minox Type)

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ic-racer

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Nice that you could check the shutter speed that way!
 

tjwspm

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Following your instructions, I removed the escapement mechanism, disassembled it, cleaned it with acetone and oiled the bearings. The new shutter speeds are now very good in my opinion.

EV: shutter speed before -> after (nominal value)
B: ok
8.5: 1/73 -> 1/35 (1/45)
10: 1/10 -> 1/60 (1/60)
11: 1/12 -> 1/80 (1/80)
12: 1/12 -> 1/88 (1/100)
13: 1/20 -> 1/110 (1/125)
14: 1/16 -> 1/130 (1/150)
15: 1/25 -> 1/150 (1/200)
16: 1/30 -> 1/180 (1/250)

I'll clean the viewfinder tomorrow. And then I'm waiting for the spare part Atoron, which I bought today for 20 euros. It reportedly has a working light meter (although it is in poor external condition).
 

tjwspm

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Current status: The spare part Atoron arrived yesterday. At the end of the week I will try, following your instructions, to remove the selenium cell and install it in my Atoron.
 
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ic-racer

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I finally got around to ordering the monocrystalline solar cells in post #21 above. It is almost the same size as the original.

It is a litte too thick for an exact fit (the case tolerances are very small, it won't squeeze in.

 
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ic-racer

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I unsoldered the black (negative) lead from the existing cell and soldered it to the marked (-) terminal of the new cell. The other end of the cell is marked (+) on the back.

Since the new cell is too thick to fit in the old mount, the old mount will not be used and the cell will just press up against the screws shown when the case is re-affixed to the front of the camera.
 
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ic-racer

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After installing the mechanism back in the case, the cell is pressed against the brass screws and makes contact. You can see meter is now functional!
 
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ic-racer

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I thought I might have to add a bleed resistor or mask part of the cell, but it works nearly perfect against the standard light source. Nothing else needs to be done.

 

4season

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That's pretty slick! Beats what I've been doing, which is cutting crystalline PV cells by hand, but they are oh so fragile. IME, there's no need to closely match the size or shape of the original selenium cell, because while silicon PV produces similar voltage as the original part, amperage is ~10x as high.
 
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ic-racer

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The lens is fixed-focus. So, where does it focus? Autocollimator says 9 feet.

 

tjwspm

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That's good to know. Thank you! It fits my table. I had always wondered what distance the camera was set to. It fits my table (9 feet = 2.74 m):
 

tjwspm

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ic-racer said:
Nice, keep us updated!
Click to expand...

Just 11 months ago and already done! The day before yesterday I installed the selenium cell from the other camera and it works.

Thanks to ic-racer for the instructions. Otherwise I wouldn't have managed it.
 
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ic-racer

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This is the adapter for the shutter speed sensor so shutter time can be measured through the collimator.

 
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