Konica Auto S3 Meter repair

Discussion in 'Classic Manual Cameras' started by davidsimon, Feb 16, 2021.

  1. Not sure if this is the right place to post this, but I could use some advice on repairing the meter on my Auto S3. I've fully stripped the camera and isolated the meter circuit (photos attached), there are clear signs of previous repairs, I beleive someone has added in a new variable resistor as shown in the attached. My confusion is in determining the correct values of these resistors to make the circuit function correctly, the S3 repair manual doesn't go into this level of detail. When the battery is installed, the meter immediately jumps to F16 (no light on the CDS). Adjusting the variable resistor to its minimum resistance and shining light on the CDS caused the meter to move back down to around f8, but no further. This seems backwards, more light should move the needle up not down? I've checked the circuit against the S3 repair manual and all seems correct. I've checked all wires and all are reading zero resistance (so seemingly no corrosion). The battery contacts are in good condition and polarity is correct. All soldering is good at the CDS contacts in the lens. Can anyone recommend a sequence of testing that would identify the issue?

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    James Bryant likes this.
  2. Update: blue and orange wires to the CDS were soldered to the incorrect contacts (according to the wiring schematic) I've swapped these over but no change to the meter behaviour, which is not too surprising as the CDS is basically just a variable resistor right? Perhaps the CDS is malfunctioning, I do get a change in resistance through it when varying the light input, but only a very small change. What should the resistance range be on these things?
     
  3. At which end of the scale does the meter pointer sit when there is no power. Maybe you could include the schematic from the repair manual. A cds resistance varies from high value at low light, to low resistance at high light. When the resistance is high ie low light, not much current can pass though the cct. When the resistance is low ie high light more current can pass through the cct. Take the battery out and meter across the cell terminals at low and high lights.
     

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