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03-26-2011, 05:31 AM   #61
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QuoteOriginally posted by OldPentaxian Quote
This tip may not work for all, but it has helped me twice over a period of time: Mount the SDM lens (e.g., 16-50mm) on an autofocus body which has no SDM contacts, e.g. the ZX-/MZ-7. Activate the screw-driven autofocus and allow the camera to focus the lens several times over a wide distance range.
This seemed to "un-jam" the SDM (and manual focus override) when I returned it to the Kaf2 mount. I've never had to have my SDM lens serviced.
You've been very lucky. The SDM on my 50-135 stopped working a while ago. Since I need to watch every penny very carefully, I decided to revert the version of my K10D's firmware back to pre SDM status. My lens works perfectly on my K10D as a screw drive lens (speed and silence are not that important to my shooting style). Every once in a while, I try the lens on my wife's K200D and it has'nt even tried to focus since the SDM stopped working.
I haven't tried this repair yet since the screw drive works so well for me.

03-28-2011, 06:30 AM   #62
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I have a guess to suggest here for why the posted repair might work for some and not for others. If the problem is some kind of resistance or sticking, if that persists very long, perhaps the motor actually does burn out somehow. But if you catch it early with this repair and fix it, all's well.

So...my 16-50 has just started misbehaving, so I plan to give it a try sometime this week.
03-31-2011, 07:40 AM   #63
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Well...looks like the repair worked for a couple weeks for me...^^^ But the thing is not focusing again...so looks like I am getting a Sigma 17-50 f/2.8, sooner rather than later. This really sucks, as I love the lens, but it isn't worth spending another $300-400 to have repaired a third time...luckily the second time was still under the first repair warranty, but if I do it a third time, that is over $700 spent on lens repair for something that might break again. I really wish someone else made a 16-50 or a say a 15-50. So I give up a few degrees of FOV with the Sigma, but I gain an AF system that works consistently.
05-05-2011, 11:32 AM   #64
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Just wanted to thank Sveinvb for putting up his detailed instructions on repairing the lens yourself.
I did it over 2 nights, with golden pin insertion testing the steady hands and patience at 3am.
My DA* 16-50mm is back in action! Will see with time if the AF accuracy remains.

05-19-2011, 08:47 PM   #65
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Different lens, same problem!

My 50-135 failed a third time yesterday (first time they "adjusted and cleaned contacts", second time replaced the SDM module). Repairs one and two were under warranty. Just for the heck of it I compared the turning resistance of the focus ring with the focus ring on my DA* 16-50, which is still OK. It was higher on the 50-135, so I spent about 10 minutes moving the focus ring back and forth, and it freed up enough to AF again. I think any time I am heading out I will free this lens up. A pain, but nothing out of my wallet, and I don't want to revert to firmware 1.2 for flash reasons.

If my 16-50 quits, I won't even bother. Lenses that wide I usually manual focus anyway. BTW, catch-in-focus works when the SDM is on the fritz.
05-28-2011, 06:41 PM   #66
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Thanks for this many times over. I used this guide as a basis for getting my lens repaired locally and saved me many $$$ and lots of time. https://www.pentaxforums.com/forums/general-technical-troubleshooting/145340-...d-locally.html

Once I work out how to give rep points I'll send a few to the OP
05-29-2011, 01:41 AM   #67
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@wizofoz

Thanks for sharing your information.

Now with this new information, I may have tried to unblock (move) the motor even more before handing it in for repair.


For the forum here are news regarding my lens:

After trying the self-repair a couple of weeks ago without success, I decided to hand in my lens for repair.

At repair I have paid about 190 Euro. It took a week to fix it. As my lens is from 2008 there is unfortunately no warranty. They said "Kamera justiert,GMR-Sensor,,Focus-Motor erneuert") (exact translation to English: "Camera adjusted, GMR-Sensor,,Focus-motor renewed").

Just a comment: Well, I wonder what's the deal about 'Camera adjusted' because I did not send a camera in, but just a lens. Also I'd like to find out what GMR-Sensor means.

regards,
Particle
06-03-2011, 07:05 AM   #68
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spare parts anyone?

I started this DIY repair a few nights ago, and one of those pesky gold contacts got away from me.

Do any of you have spare gold contacts you're willing to sell?

Attached Images
 

Last edited by Moe49; 06-03-2011 at 10:36 AM.
06-09-2011, 06:18 AM - 1 Like   #69
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A quick tip...

When re-assembling, to replace the gold contacts without having to fight with the lens, put a piece of sticky tape over the contact holes on the outside of the mount, then push in the contacts in their respective holes on the inside of the mount (except the lone spring, put that one in it's hole in the lens).

The contacts will stick to the tape and be held in place, you can then just lower the mount in place on the lens and assemble it without having to fight with and jiggle the contacts/springs.

Once the lens is re-assembled, remove the tape and clean the gold contacts with alcohol to remove all glue residue from the tape.

Wish I had taken pics, but it's pretty simple really...

Pat
06-10-2011, 04:00 AM   #70
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Hi,

To any of you who did the DIY procedure:

Would it be feasible to drill a small hole through the lens mount and the back cover?
The idea is to access the motor again without having to reopen the lens?

It might enable a 5 minute field repair, most lenses will fail "on the job", not at home.
All you'd need is the screwdriver...

I mean like here:

Name:  Q1.jpg
Views: 4565
Size:  25.9 KB

- Bert
06-10-2011, 08:03 AM   #71
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QuoteOriginally posted by bymy141 Quote
Hi,

To any of you who did the DIY procedure:

Would it be feasible to drill a small hole through the lens mount and the back cover?
The idea is to access the motor again without having to reopen the lens?

It might enable a 5 minute field repair, most lenses will fail "on the job", not at home.
All you'd need is the screwdriver...

I mean like here:

Attachment 94138

- Bert
Not sure I'd like to drill a hole in a WR lens
06-10-2011, 10:54 AM   #72
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QuoteOriginally posted by wizofoz Quote
Not sure I'd like to drill a hole in a WR lens
The hole maybe inside the O-ring, also you could seal it with some small rubber plug.
The alternative is manual focus till you get home and lens disassembly again.

- Bert
06-10-2011, 01:07 PM   #73
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QuoteOriginally posted by bymy141 Quote
The hole maybe inside the O-ring, also you could seal it with some small rubber plug.
The alternative is manual focus till you get home and lens disassembly again.

- Bert
It's not a bad idea. Why don't you try it on your lens and report back to the list?
06-10-2011, 08:12 PM   #74
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If the K10D can continue to operate DA* lens via screw AF, the SDM motor and the screw drive must be clutched from each other somehow.

I think this DIY is great, but may not be a permanent repair, there is a likely chance the problem would just come back.

Have anyone tried disabling all the SDM contacts? it looks like SDM lens has 3 extra contacts over manual screw lens. I wonder if the camera will revert the DA* lens to screw mount AF drive. that could be a permanent solution.
06-12-2011, 10:03 AM   #75
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SDM, Silent Drive Motor. It is silent because if operates on frequencies much higher than our hearing range. (It's probably very noisy for the bats.) The motor is very simple, composed of 2 elements: a metal rotor and a PZT ceramic ring. It depends on the contact friction between the ring and metal rotor to drive the rotor. The wear debris could change the contact friction or even jam it.
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