DIY SDM repair!

YankeeDan · 01-03-2016, 04:33 PM

Originally posted by sveinmb

Good news everyone.. I just did a successfull repair on my defective SDM-focus DA* 16-50!

I recently got at tip about a blog post from [a certain banned user from this forum] that referred to another Chinese Pentax user on a forum thread who had successfully repaired his 16-50 with SDM failure. The repair is quite simple and consists of turning the back part of the SDM motor itself apparently to release it from a mechanical jam.

I admit, I din't have much belief in it, but decided to give it a go anyway. When the lens first failed (well over a year ago) I actually did dismantle it to check for errors myself, but I didn't dare to touch the small screw that seems to be glued on to the back part of the SDM motor. I assumed it was supposed to be a stationary item, and I didn't want to wreck it completely before sending it in for (the rather expensive) repair. OK, I didn't want to make a complete fool of myself to be honest. I did get a quote for repair abroad, and decided to put it on hold.

However, this Chinese guys success led me into giving the DIY attempt another go. The mechanics and plastic gears in the focusing part moved just fine with no apparent problems, just as it did the first time I opened the lens. I put a scredriver into the small screw head at the back of the motor and gave it a twist - and it moved slightly. The screw and the whole back part of the motor moves. It was really tight and not easy to turn, but I gave it a bit of massage back an forth before putting the lens together again. And, believe it or not - the lens focused again on my K-7! After well over a year just collecting dust and reminding me of really bad second hand deal, I now have a fully functioning DA* 16-50 again!!

Focusing now make a little bit of a squeeking noise, but the speed seems to be just as it was before it failed. I'm wondering if a bit of carefully added lubrication could make it even better and perhaps avoid it getting jammed again in the future. However I'm not sure exactly how the SDM motor is designed and I don't want to put lubrication onto parts that should not be exposed of it.

All in all I'm quite happy right now

Having saved about 400 usd in repair costs, at least for now, and not having the dead DA* sitting on the shelf reminding me of a bad deal.. I wish I had dared fondling with the motor the first time I dismantled the lens though.

The original Chinese article can be found here (and google translate gives a nice chinglish mess of it): ÔÚWayliµÄÆô·¢ÏÂ,ÎÒÐÞÀíºÃÁËDA*16-50¾µÍ·SDM¹ÊÕÏ - ÎÞ¼ÉÂÛÌ³

UPDATE: I've made a guide for this DIY repair online.

Many thanks for the repair instructions. I've done this on a DA* 55mm which I had just about given up on. Getting the 7 contacts lined up was a trick. Tiny, tiny parts jumping about. Very fiddly but also quite straight-forward. Must have patience, steady hands, good tools and a clean work area. The lens' SDM AF works again!!

olli_tr · 01-13-2016, 02:27 AM

My DA* 60-250 SDM motor was just replaced by KEH (can recommend, fixed price of $207 including shipping). Seeing how easy this is, I'd happily replace the SDM motor myself next time, if necessary (knocks on wood). Now if we just had some way to buy a lot of SDM motors from Pentax or the OEM...

I wonder where KEH sources their SDM motors as they're not an official Pentax service center?

lotech · 01-19-2016, 02:05 AM

Hi there,

I also have problem with the 16-50, I tried to unlock the micromotor but failed, it is very stiff hard to move, so I am planning to follow the FW hack method, but I am using the K3, I don't see a clear instruction on this model, since it is my only DSLR I don't want to mess it up, does anyone successfully apply the hack to the K3 ? I have another problem, when I open up the lens I lost the 'head-less' spring, that contact point does not make contact with the camera body but the lens' mount, it may act like some kind of grounding I don't know, I tested the lens worked fine except AF, is that ok to leave it missing ?

Belcik · 01-21-2016, 01:35 PM

I would love to figure out, where to get SDM from...

rrstuff · 09-29-2016, 09:49 PM

Originally posted by lotech

Hi there,

I also have problem with the 16-50, I tried to unlock the micromotor but failed, it is very stiff hard to move, so I am planning to follow the FW hack method, but I am using the K3, I don't see a clear instruction on this model, since it is my only DSLR I don't want to mess it up, does anyone successfully apply the hack to the K3 ? I have another problem, when I open up the lens I lost the 'head-less' spring, that contact point does not make contact with the camera body but the lens' mount, it may act like some kind of grounding I don't know, I tested the lens worked fine except AF, is that ok to leave it missing ?

Ultrasonic motors are supposed to be hard to move. They work by rubbing little plastic prongs on ceramics with a direct contact. I have a device in my lab that uses US motor and moving it back and forth does help.

What helped the most was cleaning the ceramic tracks with methanol, but it might be impossible to do if the motor is enclosed in some sort of casing in a 16-50.

TheKranki · 10-17-2016, 06:57 AM - **1 Like**

Tried this a few weeks ago on my 16-50 and its still working! Thanks for the helpful thread.

alextrev · 11-20-2016, 06:36 PM

Just did it and the motor came back to life ! Thanks !!!

zoolander · 11-21-2016, 03:26 AM

Originally posted by lotech

Hi there,

I also have problem with the 16-50, I tried to unlock the micromotor but failed, it is very stiff hard to move, so I am planning to follow the FW hack method, but I am using the K3, I don't see a clear instruction on this model, since it is my only DSLR I don't want to mess it up, does anyone successfully apply the hack to the K3 ? I have another problem, when I open up the lens I lost the 'head-less' spring, that contact point does not make contact with the camera body but the lens' mount, it may act like some kind of grounding I don't know, I tested the lens worked fine except AF, is that ok to leave it missing ?

Probably necessary that little spring. The trick is to do the disassembly and reassembly in a big plastic bag. I've had parts fly like the little ball bearings and spring in the aperture ring go flying. I had to get the vacuum and them CSI it in the cannister ...... and yes I found both.

Go to some second hand pawn broker stores and find and old Pentax crusty old lens and you can scavenge it for that spring.

Simen1 · 11-26-2016, 10:30 AM

If this trick doesn't work, where can I buy a new SDM from and what would it cost?

Belcik · 11-27-2016, 10:39 PM

Originally posted by Simen1

If this trick doesn't work, where can I buy a new SDM from and what would it cost?

I am also interested in buying one

paulzhere · 12-25-2016, 01:49 AM

Many thanks for the DIY repair instructions. It just brought my 16-50 back to life. So I thought I would share my experience here.

I got a second hand 16-50 SDM which was described to be in "perfect working order without any problems". After receiving it and mounting it on my aging K20D, the focus ring won't turn. I immediately knew it was an SDM failure. I had been cheated! Ah well, I was almost about to convert it to the trusted screwdrive when I bumped into this thread. After going through the instructions and after reading about all the success people were having, I decided why not! It took me around 15-20 minutes to complete the full disassembly and re-assembly (guess it can be done much quicker but I have fiddly fingers). But yes, it was much easier than I had assumed. After screwing in the final screw I quickly mounted it on my K20D. At first nothing. A couple of half-presses of the shutter release button, still nothing. I was beginning to give up hope. Then I did something nobody should do. While still keeping the button half-pressed, I rotated the focus ring ever so slightly (highly unadvised!). Then I let the focus ring go. Half pressed the button again. Still nothing, or is it? Wait! I can see some movement. Quickly started alternating between near and far focusing. It had worked. I had just woken up the sleeping monster! My 16-50 started focusing again!

Here are a few personal observations:

1. The springs did not fly around for me, as experienced by many other members on the thread. That's because maybe I removed the mount extra slowly and extra carefully. But yes, getting them back in place and aligning them with the mount while reassembly can be quite tricky. It took me around 4-5 attempts to get it right. The key is not to lose patience. You'll get it done eventually.

2. While trying to turn the screw of the SDM motor, note that it won't budge. It is very tight and will remain that way. I, initially had the impression that since the instructions said "twist the screw back and forth", the screw would eventually free itself from the jam and start turning back and forth. That's not the case. It is very tight and is supposed to remain tight. So do not apply excessive force. The hope is that whatever force you're applying will be enough to free the mechanics "inside the motor" without the screw itself budging.

Well, so I took my 16-50 out for a stroll in to the Christmas market in the evening. Initially the motor seemed still quite "sleepy". It would take some time to wake up everytime I'd try to focus. Also sometimes it would just not focus. I had to release the button and press it again for it to work. It got better and more consistent with time though. Maybe the motor was still waking up.

Secondly, the lens is very very quiet. Much quieter than my 55 SDM and my 50-135 SDM which I have sold since. Both of them make a high pitched squeaking noise while focusing which although is not very loud is quite discernible. This one on the other hand is totally quiet (except for the slight noise of the moving parts of course). I don't know whether that is a good thing or bad (?)

Mdelleman · 12-26-2016, 01:08 PM

Hey. I took apart the lens in the tutorial (excellent thank you!) and the motor came back to life on my DA* 50-135!

Have an issue now where the viewfinder is blurry/grainy. The SDM motor is moving to AF but it can not lock on. I believe have tested my other lenses and they work fine, focus and not grainy in the viewfinder.

Help please! (-:

**RobA_Oz** · 12-26-2016, 05:59 PM

Originally posted by Mdelleman

Hey. I took apart the lens in the tutorial (excellent thank you!) and the motor came back to life on my DA* 50-135!

Have an issue now where the viewfinder is blurry/grainy. The SDM motor is moving to AF but it can not lock on. I believe have tested my other lenses and they work fine, focus and not grainy in the viewfinder.

Help please! (-:

Did you check that all the contact ball bearings and springs were back in place correctly? I can't think of another reason why that lens is failing to lock focus, assuming that you didn't move any lens elements, and that everything else was put back in place correctly. If you put the lens into manual focus mode, can you correctly focus it?

Mdelleman · 12-27-2016, 10:45 AM

Originally posted by RobA_Oz

Did you check that all the contact ball bearings and springs were back in place correctly? I can't think of another reason why that lens is failing to lock focus, assuming that you didn't move any lens elements, and that everything else was put back in place correctly. If you put the lens into manual focus mode, can you correctly focus it?

Update:

I decided to take apart the lens again and make sure everything was put back together correctly. I was much more comfortable with the tear down the 2nd time around and taped the lens contacts to the mount this time for a much easier time putting them back together! (recommended for sure).

Once back together again everything worked perfectly! I have a happy wife that is now in love with one of her favorite lenses again. She says it works like the day she bought it!

Thanks everyone.

**RobA_Oz** · 12-27-2016, 01:38 PM

Originally posted by Mdelleman

Update:

I decided to take apart the lens again and make sure everything was put back together correctly. I was much more comfortable with the tear down the 2nd time around and taped the lens contacts to the mount this time for a much easier time putting them back together! (recommended for sure).

Once back together again everything worked perfectly! I have a happy wife that is now in love with one of her favorite lenses again. She says it works like the day she bought it!

Thanks everyone.

You're welcome, and welcome to Pentax Forums.

10-17-2016, 06:57 AM - 1 Like	#186
TheKranki New Member Join Date: May 2016 Location: Broadstone, Dorset, UK Posts: 1	Tried this a few weeks ago on my 16-50 and its still working! Thanks for the helpful thread. Last edited by TheKranki; 10-17-2016 at 07:41 AM.

11-20-2016, 06:36 PM	#187
alextrev New Member Join Date: Nov 2016 Posts: 1	Success !!! Just did it and the motor came back to life ! Thanks !!!

12-25-2016, 01:49 AM	#191
paulzhere New Member Join Date: Nov 2015 Photos: Gallery Posts: 19	Another success story! Many thanks for the DIY repair instructions. It just brought my 16-50 back to life. So I thought I would share my experience here. I got a second hand 16-50 SDM which was described to be in "perfect working order without any problems". After receiving it and mounting it on my aging K20D, the focus ring won't turn. I immediately knew it was an SDM failure. I had been cheated! Ah well, I was almost about to convert it to the trusted screwdrive when I bumped into this thread. After going through the instructions and after reading about all the success people were having, I decided why not! It took me around 15-20 minutes to complete the full disassembly and re-assembly (guess it can be done much quicker but I have fiddly fingers). But yes, it was much easier than I had assumed. After screwing in the final screw I quickly mounted it on my K20D. At first nothing. A couple of half-presses of the shutter release button, still nothing. I was beginning to give up hope. Then I did something nobody should do. While still keeping the button half-pressed, I rotated the focus ring ever so slightly (highly unadvised!). Then I let the focus ring go. Half pressed the button again. Still nothing, or is it? Wait! I can see some movement. Quickly started alternating between near and far focusing. It had worked. I had just woken up the sleeping monster! My 16-50 started focusing again! Here are a few personal observations: 1. The springs did not fly around for me, as experienced by many other members on the thread. That's because maybe I removed the mount extra slowly and extra carefully. But yes, getting them back in place and aligning them with the mount while reassembly can be quite tricky. It took me around 4-5 attempts to get it right. The key is not to lose patience. You'll get it done eventually. 2. While trying to turn the screw of the SDM motor, note that it won't budge. It is very tight and will remain that way. I, initially had the impression that since the instructions said "twist the screw back and forth", the screw would eventually free itself from the jam and start turning back and forth. That's not the case. It is very tight and is supposed to remain tight. So do not apply excessive force. The hope is that whatever force you're applying will be enough to free the mechanics "inside the motor" without the screw itself budging. Well, so I took my 16-50 out for a stroll in to the Christmas market in the evening. Initially the motor seemed still quite "sleepy". It would take some time to wake up everytime I'd try to focus. Also sometimes it would just not focus. I had to release the button and press it again for it to work. It got better and more consistent with time though. Maybe the motor was still waking up. Secondly, the lens is very very quiet. Much quieter than my 55 SDM and my 50-135 SDM which I have sold since. Both of them make a high pitched squeaking noise while focusing which although is not very loud is quite discernible. This one on the other hand is totally quiet (except for the slight noise of the moving parts of course). I don't know whether that is a good thing or bad (?)

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01-03-2016, 04:33 PM	#181
YankeeDan Junior Member Join Date: Jul 2012 Location: Canberra Photos: Gallery Posts: 35	Originally posted by sveinmb Good news everyone.. I just did a successfull repair on my defective SDM-focus DA* 16-50! I recently got at tip about a blog post from [a certain banned user from this forum] that referred to another Chinese Pentax user on a forum thread who had successfully repaired his 16-50 with SDM failure. The repair is quite simple and consists of turning the back part of the SDM motor itself apparently to release it from a mechanical jam. I admit, I din't have much belief in it, but decided to give it a go anyway. When the lens first failed (well over a year ago) I actually did dismantle it to check for errors myself, but I didn't dare to touch the small screw that seems to be glued on to the back part of the SDM motor. I assumed it was supposed to be a stationary item, and I didn't want to wreck it completely before sending it in for (the rather expensive) repair. OK, I didn't want to make a complete fool of myself to be honest. I did get a quote for repair abroad, and decided to put it on hold. However, this Chinese guys success led me into giving the DIY attempt another go. The mechanics and plastic gears in the focusing part moved just fine with no apparent problems, just as it did the first time I opened the lens. I put a scredriver into the small screw head at the back of the motor and gave it a twist - and it moved slightly. The screw and the whole back part of the motor moves. It was really tight and not easy to turn, but I gave it a bit of massage back an forth before putting the lens together again. And, believe it or not - the lens focused again on my K-7! After well over a year just collecting dust and reminding me of really bad second hand deal, I now have a fully functioning DA* 16-50 again!! Focusing now make a little bit of a squeeking noise, but the speed seems to be just as it was before it failed. I'm wondering if a bit of carefully added lubrication could make it even better and perhaps avoid it getting jammed again in the future. However I'm not sure exactly how the SDM motor is designed and I don't want to put lubrication onto parts that should not be exposed of it. All in all I'm quite happy right now Having saved about 400 usd in repair costs, at least for now, and not having the dead DA* sitting on the shelf reminding me of a bad deal.. I wish I had dared fondling with the motor the first time I dismantled the lens though. The original Chinese article can be found here (and google translate gives a nice chinglish mess of it): ÔÚWayliµÄÆô·¢ÏÂ,ÎÒÐÞÀíºÃÁËDA16-50¾µÍ·SDM¹ÊÕÏ - ÎÞ¼ÉÂÛÌ³ UPDATE: I've made a guide for this DIY repair online. Many thanks for the repair instructions. I've done this on a DA 55mm which I had just about given up on. Getting the 7 contacts lined up was a trick. Tiny, tiny parts jumping about. Very fiddly but also quite straight-forward. Must have patience, steady hands, good tools and a clean work area. The lens' SDM AF works again!!

01-13-2016, 02:27 AM	#182
olli_tr New Member Join Date: Mar 2007 Posts: 15	My DA* 60-250 SDM motor was just replaced by KEH (can recommend, fixed price of $207 including shipping). Seeing how easy this is, I'd happily replace the SDM motor myself next time, if necessary (knocks on wood). Now if we just had some way to buy a lot of SDM motors from Pentax or the OEM... I wonder where KEH sources their SDM motors as they're not an official Pentax service center?

01-19-2016, 02:05 AM	#183
lotech Pentaxian Join Date: Apr 2012 Posts: 1,312	Hi there, I also have problem with the 16-50, I tried to unlock the micromotor but failed, it is very stiff hard to move, so I am planning to follow the FW hack method, but I am using the K3, I don't see a clear instruction on this model, since it is my only DSLR I don't want to mess it up, does anyone successfully apply the hack to the K3 ? I have another problem, when I open up the lens I lost the 'head-less' spring, that contact point does not make contact with the camera body but the lens' mount, it may act like some kind of grounding I don't know, I tested the lens worked fine except AF, is that ok to leave it missing ?

01-21-2016, 01:35 PM	#184
Belcik Veteran Member Join Date: Feb 2009 Location: Russia,Moscow Photos: Gallery \| Albums Posts: 377	I would love to figure out, where to get SDM from...

09-29-2016, 09:49 PM	#185
rrstuff Veteran Member Join Date: Sep 2013 Location: Pasadena, CA Photos: Albums Posts: 1,126	Originally posted by lotech Hi there, I also have problem with the 16-50, I tried to unlock the micromotor but failed, it is very stiff hard to move, so I am planning to follow the FW hack method, but I am using the K3, I don't see a clear instruction on this model, since it is my only DSLR I don't want to mess it up, does anyone successfully apply the hack to the K3 ? I have another problem, when I open up the lens I lost the 'head-less' spring, that contact point does not make contact with the camera body but the lens' mount, it may act like some kind of grounding I don't know, I tested the lens worked fine except AF, is that ok to leave it missing ? Ultrasonic motors are supposed to be hard to move. They work by rubbing little plastic prongs on ceramics with a direct contact. I have a device in my lab that uses US motor and moving it back and forth does help. What helped the most was cleaning the ceramic tracks with methanol, but it might be impossible to do if the motor is enclosed in some sort of casing in a 16-50.

11-21-2016, 03:26 AM	#188
zoolander Veteran Member Join Date: Dec 2012 Location: Gold Coast Photos: Albums Posts: 351	Originally posted by lotech Hi there, I also have problem with the 16-50, I tried to unlock the micromotor but failed, it is very stiff hard to move, so I am planning to follow the FW hack method, but I am using the K3, I don't see a clear instruction on this model, since it is my only DSLR I don't want to mess it up, does anyone successfully apply the hack to the K3 ? I have another problem, when I open up the lens I lost the 'head-less' spring, that contact point does not make contact with the camera body but the lens' mount, it may act like some kind of grounding I don't know, I tested the lens worked fine except AF, is that ok to leave it missing ? Probably necessary that little spring. The trick is to do the disassembly and reassembly in a big plastic bag. I've had parts fly like the little ball bearings and spring in the aperture ring go flying. I had to get the vacuum and them CSI it in the cannister ...... and yes I found both. Go to some second hand pawn broker stores and find and old Pentax crusty old lens and you can scavenge it for that spring.

11-26-2016, 10:30 AM	#189
Simen1 Veteran Member Join Date: Jul 2009 Location: Tromsø, Norway Photos: Albums Posts: 1,031	If this trick doesn't work, where can I buy a new SDM from and what would it cost?

11-27-2016, 10:39 PM	#190
Belcik Veteran Member Join Date: Feb 2009 Location: Russia,Moscow Photos: Gallery \| Albums Posts: 377	Originally posted by Simen1 If this trick doesn't work, where can I buy a new SDM from and what would it cost? I am also interested in buying one

12-26-2016, 01:08 PM	#192
Mdelleman New Member Join Date: Dec 2016 Posts: 2	Hey. I took apart the lens in the tutorial (excellent thank you!) and the motor came back to life on my DA* 50-135! Have an issue now where the viewfinder is blurry/grainy. The SDM motor is moving to AF but it can not lock on. I believe have tested my other lenses and they work fine, focus and not grainy in the viewfinder. Help please! (-:

12-26-2016, 05:59 PM	#193
RobA_Oz Site Supporter Join Date: Nov 2008 Location: Tasmania, Australia Photos: Gallery Posts: 8,197	Originally posted by Mdelleman Hey. I took apart the lens in the tutorial (excellent thank you!) and the motor came back to life on my DA* 50-135! Have an issue now where the viewfinder is blurry/grainy. The SDM motor is moving to AF but it can not lock on. I believe have tested my other lenses and they work fine, focus and not grainy in the viewfinder. Help please! (-: Did you check that all the contact ball bearings and springs were back in place correctly? I can't think of another reason why that lens is failing to lock focus, assuming that you didn't move any lens elements, and that everything else was put back in place correctly. If you put the lens into manual focus mode, can you correctly focus it?

12-27-2016, 10:45 AM	#194
Mdelleman New Member Join Date: Dec 2016 Posts: 2	Originally posted by RobA_Oz Did you check that all the contact ball bearings and springs were back in place correctly? I can't think of another reason why that lens is failing to lock focus, assuming that you didn't move any lens elements, and that everything else was put back in place correctly. If you put the lens into manual focus mode, can you correctly focus it? Update: I decided to take apart the lens again and make sure everything was put back together correctly. I was much more comfortable with the tear down the 2nd time around and taped the lens contacts to the mount this time for a much easier time putting them back together! (recommended for sure). Once back together again everything worked perfectly! I have a happy wife that is now in love with one of her favorite lenses again. She says it works like the day she bought it! Thanks everyone.

12-27-2016, 01:38 PM	#195
RobA_Oz Site Supporter Join Date: Nov 2008 Location: Tasmania, Australia Photos: Gallery Posts: 8,197	Originally posted by Mdelleman Update: I decided to take apart the lens again and make sure everything was put back together correctly. I was much more comfortable with the tear down the 2nd time around and taped the lens contacts to the mount this time for a much easier time putting them back together! (recommended for sure). Once back together again everything worked perfectly! I have a happy wife that is now in love with one of her favorite lenses again. She says it works like the day she bought it! Thanks everyone. You're welcome, and welcome to Pentax Forums.