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05-16-2010, 05:03 PM   #1
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Very strange SDM problem - anyone experience this?

I was out with my K20d and the DA*50-135 today, and everything was going well. After a few shots, I needed a wider angle, so I attached my DA17-70. All went well. On my way home, I stopped for another shot, and the DA 17-70 would no longer work. I was sure that it must be the lens, so I attached the 50-135 again, and that did not work either. So I tried the DA35 mm Ltd and everything was fine.

At home, I took a closer look, and then I noticed what I had not noticed in the bright sunlight: the top LCD display was blinking like mad - not flashing regularly as it will normally do, e.g. if the camera is turned on with the lens cap on the lens, but sort of "sindering". If I tilt the camera downwards away from me I can also see the gray unlit LCD characters; those are blinking like mad too.

Here's a strage fact: if I attach a non-SDM lens, the blinking stops and I can no longer see the unlit characters blinking!

Both lenses work perfectly on the K-7. And here's a funny thing: only the 50-135 will now work on the K20d, and then only intermittently, with characters in the top LCD sort of "pulsating rapidly" for lack of a better description. The DA17-70 won't work at all on the K20d, but, as said earlier, is fine on the K-7.

The only thing I can think of is that one of the lens contacts on the camera is getting a poor touch with the corresponding camera contact.

I thought of using the search feature here, but could not think of a proper search phrase.

I have cleaned the contacts on both lenses and camera (although there can't be anything wrong with the lens contacts, since both lenses work on the K-7).

I have heard of lens-related SDM problems, but never of camera related SDM problems.

Any ideas? Anyone know which contact on the camera has to do with the SDM activation (I can probably hunt this down, but if anyone knows that would save time.

Thanks in advice for any information.

(Posted on dpreview, but no suggestions, except from Eric (Viking79, who is always helpful)

And a second question:

Since I can't send the K20d off for repairs until October, I thought I would try all available recourses first, starting with a hard reset and then upgrading the firmware. Long shot, I know, but why not?

Does anyone remember offhand the procedure for hard reset? Does it just involve taking the battery out for 24 hours?

05-19-2010, 09:07 PM   #2
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I assume you checked the battery and all that fun stuff... A while back there was someone who said he'd cured his SDM problem, by blowing out the SDM feature on his camera. That or some thing to that effect, by not turning off the camera before swapping lenses. Sound like something you might have done?

05-20-2010, 05:02 AM   #3
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Jeff: Thanks for responding. Yes I have tried all the usual remedies - battery, fiddling with manual focus, etc. etc. I am now trying to effect a hard reset by leaving the battery out of the camera for a couple of days. I will then install the latest firmware, which I have not done yet (as I didn't think I would need it) but I am not optimistic.

I may well have switched lenses at some time without turning of the camera, but I really do not think that should have such drastic consequences, as that can and will happen to everyone.
05-20-2010, 06:34 AM   #4
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QuoteOriginally posted by Jonska Quote
I may well have switched lenses at some time without turning of the camera, but I really do not think that should have such drastic consequences, as that can and will happen to everyone.
It can have severe consequences. I remember the thread, just not who it was, who shorted the contacts by lens swapping. This short was enough to blow the whole SDM drivers in the camera and the photog was very happy after that, because he then could use his SDM lenses in screwdriver AF mode (well, only those lenses which support both AF systems, ofcourse).

Basically such a thing should not happen, the driver components should be protected against shorting, but they seem to be unprotected.

On the other hand, if the DA 35 kept on working on the K20, your deep reset may cure the problem.

Ben

05-20-2010, 08:00 AM   #5
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QuoteOriginally posted by Ben_Edict Quote
Basically such a thing should not happen, the driver components should be protected against shorting, but they seem to be unprotected.
I don't see how it is physically possible to short the connections. Looking at the contacts on the 50-135mm, they are obviously smaller than the gap between the contacts in the camera. There just isn't a way for contact to be made between the contacts when mounting or dismounting a lens. Wouldn't you expect the Pentax engineers to design it this way to begin with?

Thank you
Russell
05-21-2010, 02:52 AM   #6
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To Ben and Russell

Thanks for replying. I agree with Russell, that looking at the contacts on the lens t is hard to see how they could short, and in any case it seems such an elementary precaution for the designers to take that it is hard to believe that an entire team of engineers could miss it.

Latest news: a hard reset (battery 48 hours out of camera) and firmware update did not resolve the problem. Primes work fine, SDM does not. DA*50-135 works in screw drive, but top LCD display flutters.

So it's either stick the camera in the deepest recesses of my cabinet and forget it, or back to CRIS for repairs when I get to the U.S. in October. That will be the second time in the space of a few months. Getting pretty fed up.
05-21-2010, 03:14 AM   #7
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The connectors on both the camera and the lens are metal, so the contacts will all be touching the same metal surface at the same time as the lens is being rotated. If any electrical charge is sent out through the pins, it will be received through all the others. I see quite easily how a short could occur. (although I see no way for the two SDM contacts to short).

With that being so obvious, I would expect the engineers to see this as well, and build in some protections... but then again, this is not the 1950s. Things are not built to last, they have become disposable objects to be upgraded in one or two years, ensuring an revenue stream.

So, I am not all that surprised that it is left up to the user to turn off the camera before changing lenses.
05-21-2010, 03:20 AM   #8
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QuoteOriginally posted by amoringello Quote
The connectors on both the camera and the lens are metal, so the contacts will all be touching the same metal surface at the same time as the lens is being rotated. If any electrical charge is sent out through the pins, it will be received through all the others. I see quite easily how a short could occur. (although I see no way for the two SDM contacts to short).

With that being so obvious, I would expect the engineers to see this as well, and build in some protections... but then again, this is not the 1950s. Things are not built to last, they have become disposable objects to be upgraded in one or two years, ensuring an revenue stream.

So, I am not all that surprised that it is left up to the user to turn off the camera before changing lenses.
The contacts on the mounting flange are made to be shorted, as this is the simple coding for max. aperture etc. There is no danger there. I did not find the older thread about the SDM-failure by now, need to modify my search criteria...

Ben

05-21-2010, 04:11 AM   #9
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QuoteOriginally posted by amoringello Quote
The connectors on both the camera and the lens are metal, so the contacts will all be touching the same metal surface at the same time as the lens is being rotated. If any electrical charge is sent out through the pins, it will be received through all the others. I see quite easily how a short could occur. (although I see no way for the two SDM contacts to short).
I think you are confusing the data pins with the power/SDM contacts. The power/SDM contacts are not touching any metal, and there is no physical way the contacts touch the same metal surface at the same time.

The data pins carry no current and are not part of the power/SDM circuity.

Thank you
Russell
05-21-2010, 04:21 AM   #10
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Is this the thread you're looking for, Ben?

I should say that, because I'm a dolt, I often forget to turn the camera off when switching lenses and have never encountered any problem so either it's not a significant risk or I lead an extremely charmed existence.
05-21-2010, 04:37 AM   #11
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QuoteOriginally posted by dadipentak Quote
Is this the thread you're looking for, Ben?

I should say that, because I'm a dolt, I often forget to turn the camera off when switching lenses and have never encountered any problem so either it's not a significant risk or I lead an extremely charmed existence.
Yes, exactly that thread - thanks Dave!

Peter seems to have killed the SDM while mounting/unmounting the lens and I cannot quite see, how that could have happened without simply shorting some contacts. And, yes, I never switch off a camera when changing lenses, too.

Ben
05-21-2010, 04:59 AM   #12
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QuoteOriginally posted by Ben_Edict Quote
Peter seems to have killed the SDM while mounting/unmounting the lens and I cannot quite see, how that could have happened without simply shorting some contacts. And, yes, I never switch off a camera when changing lenses, too.
You are assuming the short happens outside of the lens. I'm guessing that some or maybe all of the SDM issues are from corrosion. I would bet some of the corrosion cases lead to shorting. I would bet when shorted, the corrosion explodes or melts, freeing the motors, but in some rare cases, also destroys the circuit behind it.

Since there is one case of a 50-135mm working on a K20D, but not on a K-7, I would think the K-7 now has a fused SDM circuit where the camera before didn't. The lens on the K-7 would disable SDM until the camera was powered off, I can't remember if the battery had to be pull or not as well, then reset itself allowing other SDM lenses to be used.

Thank you
Russell
05-21-2010, 04:59 AM   #13
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I still use that camera regularly and the SDM has never worked since that day. But with my other K20, K10 and now K-x, then SDM works fine with the same lens. All other functions are normal and I can't seem to repeat the issue that caused the SDM to fail in the body.

I can't offer much about the blinking display that the OP is talking about. It seems like the lenses are not connecting with the camera correctly. It could be a camera fault that is more than what I've experienced.
05-21-2010, 08:30 AM   #14
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This whole thing sounds exactly like what happened to my Sigma 150-500mm with HSM. All the indications in the viewfinder and the LCD on my K20D and K-x were very erratic when it was mounted. No problems with any other lens. Luckily the lens was under warranty and was fixed by C.R.I.S. in Arizona. Maybe I was complacent and switched lenses when the camera was on??? I cannot be sure....
05-21-2010, 01:16 PM   #15
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QuoteQuote:
I think you are confusing the data pins with the power/SDM contacts. The power/SDM contacts are not touching any metal, and there is no physical way the contacts touch the same metal surface at the same time.

The data pins carry no current and are not part of the power/SDM circuity.
Unless communication between devices is done with magic smoke, the pins must certainly cary some current. Not sure how else this stuff would work. Somehow I question the magic smoke idea.

Still, I did comment that I see no way the SDM contact should short, I mean its surrounded in a plastic housing, so there was also certainly no confusion there.



Anyway, its all a computer, one way or another. There is also always the possibility of static charge being present to a degree that might over load any thing that was designed to handle super high voltages.

It is also possible that the OP played no part in the problem, and the damn thing just broke.
e.g My K7 is in repair for a handful of problems that likely could not be caused by any particular cause. (metering is way off - same scene meters from 2s, 1/250s through 1/3200s. The hot shoe is intermittently flaky, memory cards intermittently cannot be read. Lenses may not focus.)
The main CPU is likely just FUBAR.

Electronics have a certain failure rate, I probably just got stuck with a crap version.
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