Rollei 35 S: CdS meter calibration?

[dsandlund]

Rollei 35 S repair question here. Does anyone have the proper procedure for calibrating the CdS meter (in a Rollei 35 S)?

There are two potentiometers inside (one accessible from the side and one from the rear of the camera). I had to replace the side potentiometer because a previous owner decided to mangle it.

Both potentiometers have one leg connected to one side of the CdS cell, which in turn has its other side connected to the battery. What the other leads go to is a mystery since I haven't disassembled the camera further and would like to avoid it.

Right now I've resorted to turning the side potentiometer to adjust the needle in low light, and the rear potentiometer to adjust the needle in stronger light. That's just guessing, although I seem to have come close to consistently correct meter readings this way.

I'm sure there's a proper procedure, but I've not been able to find one?

Thanks,
Daniel

 

[sterioma]

I have the 35 camera, which should be similar but unfortunately I don't know the answer. However, the repair manuals are available online, I did save a copy just in case when I acquired mine.

I downloaded the manual here: https://learncamerarepair.com/downloads/pdf/Rollei-35-repair-manual.pdf
At page 9 there is something about the exposure meter adjustement. Hope this helps.

 

[dsandlund]

Thanks. However my understanding is that the adjustment they are referring to is for the orange matching hole that moves with selected shutter speed and aperture. This is consistent with the half hole being visible at 1/2s and f/8 at 21 DIN (100 ASA) that they're talking about (and the item to bend in order to adjust this is indeed to this mechanism).

I need to make the white needle deflect properly to varying light levels, which is a different mechanism.

 

[MildMiles]

Dsandlund, I just found this thread, and as I myself am dealing with pots that have fallen apart due to corrosion, I was wondering if you could share what the max resistance of the originals are. And were they logarithmic or linear?

 

[Bill Burk]

I didn’t take photos or notes but I calibrated mine to a fresh alkaline cell against a trusted light meter by trial and error. The two potentiometers are essentially slope and intercept. One determines the needle position directly while the other determines how much the needle moves across in response to light.

 

[MildMiles]

Thank you. Perhaps I misunderstood, though. From your original post I was under the impression that you had replaced the side potentiometer. I'm trying to determine if replacement potentiometers are sourceable.

 

[Bill Burk]

No my originals were OK