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I am now trying to fix a camera control wheel, like the one in the top right corner of this camera (not the one which I am fixing):

Fujifilm S5

This is a cheap part but I cannot find a replacement for my camera model (yes, I have searched thoroughly) and I cannot bet on that whatever else I find will fit in. I have took it apart and I am totally confused.

What I see here is 12 clicks per full rotation wheel (I see the clicking circle grill) with plastic parts. A small PCB has three outputs (three stripes on the bottom) and two grounds (two pins on the sides), the brush set only touches the PCB and nothing else. The brush does not move closer or further from PCB, it is fixed at some distance.

Now, THIS is expected to be able to deduce a click from every 30 degree position change:

https://i.sstatic.net/cftoU.jpg - contact plate, brushes and 120 degree rotation simulation with correct starting position.

https://i.sstatic.net/32skB.jpg - PCB with oil and friction marks outlined

Even more: the contact plates (bright places of PCB) seem to be not conductive at all - measured resistance between two points of same plate is >2MOhm.

How is it expected to work at all given that no details are missing? Is it more than a contact shortening device?

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  • \$\begingroup\$ Please add better tags if there are any. \$\endgroup\$
    – Euri Pinhollow
    Commented Sep 11, 2016 at 17:57
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    \$\begingroup\$ Without regard to the specifics, devices like this are usually quadrature encoders, but a larger number of channels is possible. Perhaps it is not making contact because it is damaged, or possibly it uses capactive sensing rather than conduction. The CF card suggests this may be an older model, so perhaps this is a common failure - see if anything is known among photography enthusiasts who have it. \$\endgroup\$
    – Chris Stratton
    Commented Sep 11, 2016 at 18:22
  • \$\begingroup\$ @chris-stratton: camera is a random one (edited for clarity). I measured resisance between two points of the same area, not two different contacts. \$\endgroup\$
    – Euri Pinhollow
    Commented Sep 11, 2016 at 18:39
  • \$\begingroup\$ You are unlikely to find a commercial replacement for this proprietary designed part. But it looks like a Y to delta 3 R carbon film rotary potentiometer for rotary position sensing. \$\endgroup\$
    – D.A.S.
    Commented Sep 11, 2016 at 19:28
  • \$\begingroup\$ I'm wondering if you're overthinking this. You want to replace it because it doesn't work, so any measurements you make on this non-functional part might tell you nothing. \$\endgroup\$
    – Roger Rowland
    Commented Sep 11, 2016 at 19:29

1 Answer 1

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You are unlikely to find a commercial replacement for this proprietary designed part.

The two ground taps and two inputs with two outputs with conductive carbon tracks create a quadrature sin-cosine rotary analog encoder for position with mechanical detente for stability for rotary position sensing.

Either the contact pressure of carbon surface contaminants have degraded in this part. enter image description here

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