DIY SDM repair.

[Joseph Tainter]

Incidentally, it is interesting to see that the SDM and shaft-drive AF mechanisms are linked. Perhaps this has something to do with the apparently higher failure rate of lenses that have both AF mechanisms.

Joe

 

[John Cafarella]

The aim of the "repair seems to bee just to get the SDM motor to turn, yeah?

Would spinning the screw drive on the lens mount not do the same thing without all the hassle of disassembling?

--
John Cafarella
Melbourne, Australia

 

[Russell Evans]

Sorry, but that is not a real repair because the procedure does not address the source of the problem.

I personally have always thought the issue was corrosion in the motor. Twisting the motor to break the corrosion, and maybe grind it off would be a repair. If you've ever scraped the corrosion off a distributor, you'll understand the reason it would be considered a repair.

Thank you
Russell

--
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[onesidedcoin]

If it is corrosion it may be a result of the lubrication used on the shaft and motor bearings.

Just speculation but if this technique does free up the motor the problem is where the motor shaft and the bearings ride or anther shaft/bearing on the gear train

I would assume the motor/gear train shafts incorporates sleeve bearings and the defect easily correctable with the right bearing/shaft material for future lens and repairs for products already in the market. I doubt Pentax builds these motor but needs to work on the failure rate with their vendor.

Sorry, but that is not a real repair because the procedure does not address the source of the problem.

I personally have always thought the issue was corrosion in the motor. Twisting the motor to break the corrosion, and maybe grind it off would be a repair. If you've ever scraped the corrosion off a distributor, you'll understand the reason it would be considered a repair.

Thank you
Russell

--
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--
Dave

 

[Eric O]

One thing that is quite interesting is that the SDM drives the same system as the screw drive motor. Why not just build a high quality ultrasonic motor into the camera and couple that to the lens via the screw drive? That would deliver next to silent and fairly fast AF on all lenses, right?

It's the screw drive that makes most of the noise, not the motor, so no. Electric motors are fairly quiet, but the screw drive in this case is a gear-reduction mechanism that makes noise. Think of it like a miniature automobile transmission. It is difficult to make a screw-drive mechanism even somewhat quiet unless you make it out of plastics, which would wear out.

 

[GPGeneralPhoto]

Read about it here:

pentaxforums.com/forums/pentax-slr-lens-discussion/130429-diy-supersonic-drive-motor-repair.html
Add the http://www .

--
I'm thankful to still be able to...

 

[jonathan68]

It looks like it's worth a try if you have a stuck one that's out of warranty. But watch out when the vacume cleaner approaches ...

Yes... definitely do not pause this operation to do the vacuum cleaning. Also, do not perform on a shag pile carpet or on a sandy beach. And do not cover the bits in dog food and leave them in the dog bowl.

lock

--
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[jonathan68]

The aim of the "repair seems to bee just to get the SDM motor to turn, yeah?

Would spinning the screw drive on the lens mount not do the same thing without all the hassle of disassembling?

Yes that's what worked for me.

--
John Cafarella
Melbourne, Australia

--
http://www.pictasmagoria.com
http://pictasmagoria.blogspot.com

 

[awaldram]

Sorry, but that is not a real repair because the procedure does not address the source of the problem.

I personally have always thought the issue was corrosion in the motor. Twisting the motor to break the corrosion, and maybe grind it off would be a repair. If you've ever scraped the corrosion off a distributor, you'll understand the reason it would be considered a repair.

I'm confident its nothing more than sticktion caused by the close tolerance manafacture of the stator.

This is why there is more occurences for people who rarely use ther lens Vs those who often use it.

As the stator wears the chances for failure will decrease, (how about that for a positive spin).

There may be a contaminate element.

I do feel vindicated in my assertion that ultrasonic motors don't just burn out especially given the riddicule it recieved , Guess 1 up to physics Vs hysterics.

Thank you
Russell

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[awaldram]

The aim of the "repair seems to bee just to get the SDM motor to turn, yeah?

Would spinning the screw drive on the lens mount not do the same thing without all the hassle of disassembling?

Yes that's what worked for me.

Yep providing the clutch grips enough to break the bond then any action will affect a repair.

1 spin the Manual AF
2 Spin screw drive AF
3 directly spin SDM motor

This of cause wont fix those failures where the gasket has slipped jamming the barrel.
Or where the drive circuit has been damaged by the stall current.

--
John Cafarella
Melbourne, Australia

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[wlachan]

The aim of the "repair seems to bee just to get the SDM motor to turn, yeah?

Would spinning the screw drive on the lens mount not do the same thing without all the hassle of disassembling?

Yes that's what worked for me.

If that's the case, sounds like the QS mechanism built-in to the screw drive stuck and jammed the SDM. I have learnt from DA10-17 & DA16-45 that QS do jam quite often, usually when the camera failed to disengage at the end of AF by turning the shaft backward.
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[narddogg81]

looks easy enough
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[MightyMike]

Alright, i have a crazy idea... it appears that a manual amount of twisting of the motor helps it in a number of cases... what is the voltage and that sort of stuff that the motor works on? can someone make a small device to put across the contacts and drive the motor a little harder back and forth simulating what we'd do with out hand so we wouldn't have to take it apart.

Its probably just as risky, one would have to be sure not to fry it and perhaps find a way of detecting resistance and having a cut-off when the resistance is too high.

so is the idea plausible or nuts?
--
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[awaldram]

Sorry Mike its nuts

An ultrasonic motor will not generate more torque by feeding extra volts to it .

Actually if you stuffed power down the PZ pins nothing would happen as without the drive circuit activating the power does nothing.

All you could achieve is a plume of smoke as the circuits melted.

Alright, i have a crazy idea... it appears that a manual amount of twisting of the motor helps it in a number of cases... what is the voltage and that sort of stuff that the motor works on? can someone make a small device to put across the contacts and drive the motor a little harder back and forth simulating what we'd do with out hand so we wouldn't have to take it apart.

Its probably just as risky, one would have to be sure not to fry it and perhaps find a way of detecting resistance and having a cut-off when the resistance is too high.

so is the idea plausible or nuts?
--
Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote '



http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=180&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=

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[MightyMike]

you see thats what this forum is for... making sure people don't do stupid things LOL
--
Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote '



http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=180&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=