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10-16-2016, 12:39 PM   #1
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K-3 Lens Mount problem - loose wire behind the mount

Well, today is not a very good day for me.
Following some trouble with a M42 macro bellows on my K-3 I had to disassemble my lens mount.

Not a good idea, as I managed to break a wire that was soldered on metal ring behind the lens mount...
The "metal ring" I'm talking about is on the left in the photo below ((c)Dave Robinson, taken from this post: https://www.pentaxforums.com/forums/114-maintenance-repair-articles/306083-k-...nt-repair.html).

So I assembled the lens mount without the wire connected to that piece. The AF works fine on the 16-50 (I haven't tried any other lenses yet).
Could someone tell me what that wired did? I think the "metal ring" it's some kind of a contact but I cannot understand what it does.

Thank you for your help!
Stefan

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10-16-2016, 12:45 PM   #2
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grounding wire I think
10-16-2016, 12:53 PM   #3
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That's the ground wire that is used for the electrical and electronic connections of the KA-KAF mount lenses. Without a proper ground connection the camera body will not be able to determine if a KA+ lens is mounted, what the focal length is, minimum and maximum f-stop and whatever digital is sent by KAF+ lenses.

Without a solder joint the physical connection of the ground wire to the lens mount could fail for various reasons - oxidation, movement or flattening of the wire.

Failure of the connection will probably manifest itself with the "F- -" in the viewfinder and not be confined to one lens. Fiddling things about may temporarily restore the connection but the permanent solution would be to solder the wire properly.
10-16-2016, 01:11 PM   #4
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QuoteOriginally posted by Not a Number Quote
That's the ground wire that is used for the electrical and electronic connections of the KA-KAF mount lenses. Without a proper ground connection the camera body will not be able to determine if a KA+ lens is mounted, what the focal length is, minimum and maximum f-stop and whatever digital is sent by KAF+ lenses.

Without a solder joint the physical connection of the ground wire to the lens mount could fail for various reasons - oxidation, movement or flattening of the wire.

Failure of the connection will probably manifest itself with the "F- -" in the viewfinder and not be confined to one lens. Fiddling things about may temporarily restore the connection but the permanent solution would be to solder the wire properly.
OK, from what I see in the pictures taken after I managed to assemble the camera mount, the Raw files contain all the information (iso, time, f-stop, etc). So everything seems to work fine, for now...
If I understood right I should solder the wire in order to avoid a F-- error in the future?

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