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03-27-2016, 03:43 PM   #31
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Hi,

Please look at my post (#7) in this thread:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/309581-da-1...fix-check.html

I can confirm working method with a small screwdriver, someone mentioned earlier. If anything I would strongly advise not to use AF to force SDM motor to move stuck parts inside the lens. Trying to so may actually overstrain the SDM motor and kill it.

03-29-2016, 11:08 AM   #32
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QuoteOriginally posted by GeneV Quote
If the theory is that it is just the clutch, then it should not work on the 17-70, with no quick shift clutch or screw drive. Mine only has issues above 55mm, so that is likely to be a different issue altogether. Some others have had the SDM fail entirely.
the copy I am selling has the same issue.
sdm seems fine, though
10-27-2016, 09:33 AM   #33
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Okay, I thought I'd want to post this. After a few years of having to warming up my 16-50 to auto focus, it is no longer there. About 2 months now, I can leave the lens in my bag for a long time, and put it back on and it'll auto focus right away without having to do the warm-up tactics. The SDM works perfectly fine now. It is very strange.
11-11-2016, 10:37 AM   #34
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QuoteOriginally posted by LeDave Quote
Okay, I thought I'd want to post this. After a few years of having to warming up my 16-50 to auto focus, it is no longer there. About 2 months now, I can leave the lens in my bag for a long time, and put it back on and it'll auto focus right away without having to do the warm-up tactics. The SDM works perfectly fine now. It is very strange.
My 16-50 does the same. It makes me want to get a new one since it's my most used lens but yet I don't want to get a new one because it still works great...when it wants to work.

11-12-2016, 03:35 AM   #35
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Hi, as I sad in my thread. Most likely the reason behind weird af behaviour is thickening grease. Possibly in clutch. Turning af screw with a small screwdriver back and forward few times usually solves the problem.
11-18-2016, 10:33 AM   #36
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QuoteOriginally posted by LeDave Quote

3/5/2016 Update:

Hey guys, I found another cheap way to quick fix the SDM problem. You just hold the AF button down for a couple of seconds and let go, then you hold the AF button down for a couple of seconds and let go, repeat, repeat, and repeat until it starts to move and focus again.
Just three days ago I revived my seemingly defunct 16-50 AF using this method. Yesterday it needed revived again, but it didn't take quite as long to respond. This morning it again needed some coaxing to function normally, but not as much as the day before. I will continue this for the next couple of weeks, but if it doesn't soon start responding first time, every time as it is supposed to I will be sending it off to Uncle Vanya for a conversion.
I have had this lens since November 2012 and had the SDM repaired under a Square Trade warranty just a few months after the original Pentax warranty ran out. I am just getting tired of dealing with it.
11-18-2016, 11:23 AM   #37
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QuoteOriginally posted by chuck_c Quote
Just three days ago I revived my seemingly defunct 16-50 AF using this method. Yesterday it needed revived again, but it didn't take quite as long to respond. This morning it again needed some coaxing to function normally, but not as much as the day before. I will continue this for the next couple of weeks, but if it doesn't soon start responding first time, every time as it is supposed to I will be sending it off to Uncle Vanya for a conversion.
I have had this lens since November 2012 and had the SDM repaired under a Square Trade warranty just a few months after the original Pentax warranty ran out. I am just getting tired of dealing with it.
Just curious to know how you keep the lens when it is not being used. When I am not using the lens (lens don't get used often except on gigs and assignment) I keep the lens standing up with front element down not sideways. This way, it puts less strain on the SDM motor (to get stuck), it works for me every time when I need to use it. I have no scientific explanation for that, but it is worth a try in your case.
11-18-2016, 02:50 PM   #38
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QuoteOriginally posted by chuck_c Quote
Just three days ago I revived my seemingly defunct 16-50 AF using this method. Yesterday it needed revived again, but it didn't take quite as long to respond. This morning it again needed some coaxing to function normally, but not as much as the day before. I will continue this for the next couple of weeks, but if it doesn't soon start responding first time, every time as it is supposed to I will be sending it off to Uncle Vanya for a conversion.
I have had this lens since November 2012 and had the SDM repaired under a Square Trade warranty just a few months after the original Pentax warranty ran out. I am just getting tired of dealing with it.
QuoteOriginally posted by aleonx3 Quote
Just curious to know how you keep the lens when it is not being used. When I am not using the lens (lens don't get used often except on gigs and assignment) I keep the lens standing up with front element down not sideways. This way, it puts less strain on the SDM motor (to get stuck), it works for me every time when I need to use it. I have no scientific explanation for that, but it is worth a try in your case.
All of my SDM lenses are stored either face up or face down. I have had zero failures but I have no idea if that is related in any way. I'm reluctant to imagine it is that simple. I am more inclined to think that some other part in the lenses that have multiple failures (or a common camera issue) is related. If there is undue drag internally or weird current/voltage fluctuations perhaps these have an impact over time on the tiny motors. In any case I don't know the answer but I do know that converted lenses seem to just work so I am happy to offer that service to those who need it.

11-18-2016, 06:07 PM   #39
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QuoteOriginally posted by aleonx3 Quote
Just curious to know how you keep the lens when it is not being used. When I am not using the lens (lens don't get used often except on gigs and assignment) I keep the lens standing up with front element down not sideways. This way, it puts less strain on the SDM motor (to get stuck), it works for me every time when I need to use it. I have no scientific explanation for that, but it is worth a try in your case.
With the exception of a couple extra long telephoto lenses, I store all of my lenses either face up or face down.
11-18-2016, 11:20 PM   #40
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QuoteOriginally posted by chuck_c Quote
With the exception of a couple extra long telephoto lenses, I store all of my lenses either face up or face down.
Ah well. I figured. It would be far too simple if that were the difference.
11-24-2016, 06:56 PM   #41
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it works for me by just pushing the AF button

but after the SDM start to work,

I try the method of turning the lens 360deg, thinking that it will make the lens smoother.
but WRONG thing to do . the O'Ring within the lens broke and it went it to the "Range indicator" of the lens.
Now my lens is struck, cannot even manual focus the lens
11-24-2016, 07:29 PM   #42
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QuoteOriginally posted by morganoh Quote
it works for me by just pushing the AF button

but after the SDM start to work,

I try the method of turning the lens 360deg, thinking that it will make the lens smoother.
but WRONG thing to do . the O'Ring within the lens broke and it went it to the "Range indicator" of the lens.
Now my lens is struck, cannot even manual focus the lens
Ugh. Time to send to KEH. Which specific lens is it? 16-50? 50-135? 200? 300?
12-08-2016, 01:42 PM   #43
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After my 16-50 works again without warm-up, I realize that a seal broke as well. There feels like air pumping out of between the gaps of the zoom ring and the meter area. It's not sucking in either, just blowing out.



The safe side is doing this, "I found another cheap way to quick fix the SDM problem. You just hold the AF button down for a couple of seconds and let go, then you hold the AF button down for a couple of seconds and let go, repeat, repeat, and repeat until it starts to move and focus again."
01-09-2017, 12:19 AM   #44
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Worked for my DA*55, but not for my DA17-70

Both motors were replaced by big $. Both failed to work again. My DA*55 is not revived. But not my DA17-70. Not sure to be or
01-09-2017, 07:19 AM   #45
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QuoteOriginally posted by yyyzzz Quote
Both motors were replaced by big $. Both failed to work again. My DA*55 is not revived. But not my DA17-70. Not sure to be or
Sorry I'm a little confused. Both of these lenses had their motors replaced and neither one works? Did the replacement fail right away? Did you have to pay for an unsuccessful repair or were these working and then they died?
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