[daunbailoo]

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Hi, I have just followed the very clear instructions. It was very easy to disassemble the rear lens mount (DA 16-50/2,8 with a not working SDM). Only in the reassemblement I have had some troubles in the positioning of the golden pins. Anyway at the end of the job the AF worked again but only for 9/10 shots. Has anyone else had the same result I have had? Many thanks for the replay.

[mee]

The pins were the most difficult part for me, besides the handling of the delicate aperture spring. I aligned the pins and gently turned the camera (pins near me) towards me. That made most of them align properly and the couple that were still not in position (before lowering the mounting plate) I gave a very gentle nudge to with some tweezers. Make sure all the pins are in the correct location.

On some lenses, one can put some tape over the pins BEFORE removing the cover mounting plate and that will adhere to them all making the job easy. On this lens, it didn't work so well for me, so I had to resort to aligning one by one as aforementioned.

Make sure your lens is not front or back focusing too.. you might need some AF micro adjustment which might account for the AF not working on the single missed shot.

[MarcelG]

I followed these instructions and fixed my DA*16-50 that failed on me yesterday.
Thank you very much. Saved me 300 euros!!!!

BTW, I decided to make a video of my efforts, just for fun and for sharing with those who do not feel comfortable with just photo's of what needs to be done.
It's in dutch, but with the photo guide on the side, it all makes sense.

Here it is (in about 10 minutes or so) :

Youtu.be

Youtu.be

[pentasonic49]

My 16-50 is still ok since my second strip down (post 152 in the middle of 2013). I point the camera/lens at a plain background to fool the autofocus and turn the focussing ring to infinity. Pressing the AF button should cause the SDM motor to run to min focus and back to infinity. I repeat this about six times to exercise the SDM. If this fails, I can fall back on the screwdriver method.

[WillyKano]

Hey,


Does anyone know where I could get the two sealing rubbers that are used within the SMC DA* 1:2.8 16-50mm ED AL [IF] , one of them is broken?


txs,


WillyKano

[zoolander]

Hey,


Does anyone know where I could get the two sealing rubbers that are used within the SMC DA* 1:2.8 16-50mm ED AL [IF] , one of them is broken?


txs,


WillyKano

Thats a very good question !

What I would do (Seeing how Pentax won't sell you the o-ring), I would buy a digital caliper to measure the o-ring, and the diameter of the recess where it sits, and the thickness of the o-ring.

Take those measurements and jam it into Google and see whats out there.

If you find the correct size in rubber then order it. There also might be a silicon type which is usually red/orange in color, these are more durable in terms of strength and heat than rubber, because rubber can break down quickly.

If you cannot find the exact size, and all thats available is something a touch bigger or smaller, I'd still give it a try.

Here's a link to an online o-ring company in the U.S:

O-Rings, Inc. Since 1958 - Buy Online

Keep trying, I think you might be able to find one.

[Stavri]

Has anyone had success with sleepy* SDM motors when using this technique?


*when the motor needs a few minutes to wake up and respond properly, early signs of pending SDM failure

[jfuqua11]

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 - ÎÞ¼ÉÂÛ̳

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

Works!!!!!! Took me about 10 minutes. The only thing was after the focusing was a little slow at first but then after focusing a few times it was back to normal! Here are pictures, sorry the are not great quality but my lens for my K3 was being worked on haha I tried to highlight the screws and all. on the outer layer there are 5 silver screws then after this part there are 4 black screws when you take the black part off be careful because the contacts and springs will fall out (best to take this part off upside down so the springs and contacts don't fall into the lens. There will be 6 springs with contacts on them and 1 spring without a contact (all are gold in color) Then on top is the motor and just use the screw driver to work it (turn it) back and forth and reassemble. Nothing difficult at all.

[lotech]

Great post !! I dropped my 16-50 on to concrete floor and the SDM dead as well as the camera SR module, thanks God it is still under warranty and no external damage so I got them repaired for free, but then the SDM failed again just after the warranty, it still work 50/50 not completely dead, since the repair cost shocked me I leave it that way. Then later I upgraded from K5 to K3, and I find the lens close to completely dead, it seems K3 has less driving power than the K5 , while the motor is working on the K5 it won't move a bit on the K3, and it took quite a while to 'wake it up' from sleep. I also tried to turn the driving shaft on the lens to free the motor as someone suggested, but that won't fix the problem.

[Bagga_Txips]

This thread seems to have a very long lifespan! I just had a thought - wasn't there a court case in the UK some time ago where someone had a faulty washing machine or something, outside the one year guarantee period, and the legal system ruled that the ''expected lifespan'' of an expensive item should exceed the stated warranty period? As a result I believe Costco in the UK were repairing or replacing machinery several years after purchase.

Surely the SDM problem is a similar case? Start small claim court actions against Pentax or the retailers and something would be done quite quickly, I reckon.

[tgclark56]

My da 16-50mm will not focus. I tried this fix it did not work for me but my work for others.

[Belcik]

Well, approach this as well with my 50-135. Some findings.

1. Really easy to disassemble and pretty easy to assemble.
2. For those having problems with pins - Put the pins with the additional springs into their respective holes in barrel, then take a white plastic thing that they go into in the ring that goes on top. Put plastic on them and align with needle. Press - and they are on place. Later it is a pencake to put a ring over a barrel.
3. Watch the sealings. Not only the one that you see when diassebling, Between the zoom ring and focus ring there is also one that likes to fell off and you need to align.
4. Disassembled and repeated the excercise 5 times. Did not work. I took the more radical approach with dismounting the whole pcb part with gears and SDM (as described i other places). The connecting piece (07374 on picture) snapped. So I ended up with converting to screwdrive....

Question - any idea where to buy SDM motor, this dismounting and mounting became addictive

[zoolander]

Question - any idea where to buy SDM motor, this dismounting and mounting became addictive

The only place I found was on ebay where they sell similar micro motors (and full ring motors) for Nikon and Canon lenses. Here's an example that could be adapted, you never know: High Quality Lens Focus Zoom Motor FOR Nikon 18 55mm 18 105mm 18 135mm 16 85mm | eBay

[Belcik]

Similar, but not the same...

[sebas77]

worked for me first try on my 17-70.

The only doubt I have is if I screwed the SDM screw too tight. after I screwed clock-wise/anti clock-wise 3-4 times, I wasn't able to turn it again (too tight?).

The lens now works again (it wasn't work at all before), but I think it's a little bit louder. It squeaks like a not oiled old hinge.