Faulty SMC Pentax AF Zoom 1:2.8 35~70mm

**limestonecowboy** · 08-06-2018, 11:03 AM

I have two faulty f2.8 AF 35-70mm lenses

No.1 has 1 broken (missing) battery contact. Front plate has been damaged by previous owner trying to get into battery compartment. Lens is ok but needs cleaning out.

No.2 has slight scratches to lens, focus works in one direction only.

Does anyone have drawings/diagrams showing the internal wiring for this lens? I'm hoping two faulty lenses will make one good one.

Any help appreciated.

Nick

**othar** · 08-06-2018, 02:12 PM

Originally posted by limestonecowboy

I have two faulty f2.8 AF 35-70mm lenses

No.1 has 1 broken (missing) battery contact. Front plate has been damaged by previous owner trying to get into battery compartment. Lens is ok but needs cleaning out.

No.2 has slight scratches to lens, focus works in one direction only.

Does anyone have drawings/diagrams showing the internal wiring for this lens? I'm hoping two faulty lenses will make one good one.

Any help appreciated.

Nick

I don't know that lens (which brand?) but wouldn't it be easier to switch the glasses and leave the wiring alone?

pschlute · 08-06-2018, 03:07 PM

Originally posted by othar

I don't know that lens (which brand?)

AF 35-70/2.8 | The K-Mount Page

**othar** · 08-06-2018, 04:17 PM

Ah, that lens
SMC Pentax-AF 35-70mm F2.8 Reviews - M Zoom Lenses - Pentax Lens Reviews & Lens Database

I just re-read your post and realised I overlooked the part with focuses in one direction only, in that case good luck with the wiring.

**twilhelm** · 08-06-2018, 07:44 PM

The focus in one direction only issue is likely a faulty focus motor. But no, I’ve never seen a diagram for one.

**limestonecowboy** · 08-07-2018, 05:40 AM

I'm presuming there is some sort of switch which tells the motor to rotate the other way at the limit of each direction.

I'm loathe to open these up.

glasbak · 08-07-2018, 10:48 AM

Originally posted by pschlute

AF 35-70/2.8 | The K-Mount Page

And this page may be of interrest too, clean the contacts ?

**limestonecowboy** · 08-07-2018, 01:36 PM

A prize for that post, it still only focusses toward infinity (and doesn't stop) just keeps trying to push past infinity. I suspect there is a loose wire or more cleaning to do.

08-06-2018, 11:03 AM	#1
limestonecowboy Site Supporter Join Date: Aug 2016 Location: Newcastle upon Tyne Photos: Albums Posts: 151	Faulty SMC Pentax AF Zoom 1:2.8 35~70mm I have two faulty f2.8 AF 35-70mm lenses No.1 has 1 broken (missing) battery contact. Front plate has been damaged by previous owner trying to get into battery compartment. Lens is ok but needs cleaning out. No.2 has slight scratches to lens, focus works in one direction only. Does anyone have drawings/diagrams showing the internal wiring for this lens? I'm hoping two faulty lenses will make one good one. Any help appreciated. Nick

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08-06-2018, 02:12 PM	#2
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	Originally posted by limestonecowboy I have two faulty f2.8 AF 35-70mm lenses No.1 has 1 broken (missing) battery contact. Front plate has been damaged by previous owner trying to get into battery compartment. Lens is ok but needs cleaning out. No.2 has slight scratches to lens, focus works in one direction only. Does anyone have drawings/diagrams showing the internal wiring for this lens? I'm hoping two faulty lenses will make one good one. Any help appreciated. Nick I don't know that lens (which brand?) but wouldn't it be easier to switch the glasses and leave the wiring alone?

08-06-2018, 03:07 PM	#3
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,215	Originally posted by othar I don't know that lens (which brand?) AF 35-70/2.8 \| The K-Mount Page

08-06-2018, 04:17 PM	#4
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	Ah, that lens SMC Pentax-AF 35-70mm F2.8 Reviews - M Zoom Lenses - Pentax Lens Reviews & Lens Database I just re-read your post and realised I overlooked the part with focuses in one direction only, in that case good luck with the wiring.

08-06-2018, 07:44 PM	#5
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	The focus in one direction only issue is likely a faulty focus motor. But no, I’ve never seen a diagram for one.

08-07-2018, 05:40 AM	#6
limestonecowboy Site Supporter Join Date: Aug 2016 Location: Newcastle upon Tyne Photos: Albums Posts: 151 Original Poster	I'm presuming there is some sort of switch which tells the motor to rotate the other way at the limit of each direction. I'm loathe to open these up.

08-07-2018, 10:48 AM	#7
glasbak Veteran Member Join Date: Apr 2009 Location: Netherlands Posts: 369	Originally posted by pschlute AF 35-70/2.8 \| The K-Mount Page And this page may be of interrest too, clean the contacts ?

08-07-2018, 01:36 PM	#8
limestonecowboy Site Supporter Join Date: Aug 2016 Location: Newcastle upon Tyne Photos: Albums Posts: 151 Original Poster	A prize for that post, it still only focusses toward infinity (and doesn't stop) just keeps trying to push past infinity. I suspect there is a loose wire or more cleaning to do.