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12-03-2012, 09:16 AM   #1
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SDM 50-135, not dead, but not working

There is a problem with SDM 50-135. Would you help locate, what part is broken.
It is not looks as standard problem with motor, as I have with 16-50.
When I put 50-135 on K20D, MF is blinking, autofocus not working, after switch to "Manual" on lens and body
you can not see red square on focusing screen and there is no confirmation of manual focusing. Moreover, it is
not possible to switch on "Fn", screen appears for second and disappeared. Body recognize lens as "A".
When I check this lens on K-01 it is dosn't work too.
But when I had isolate (by tape) one pin of SDM motor contacts on lens (two square contacts on bayonet) and try it
again - all works fine. SDM motor focusing fine on K-01. When I try the same on K20D, nothing change compared
with situation as I describe at the beginning. So SDM is working, but what is wrong with my lens?
Why it works on K-01 and not on K20D?

12-03-2012, 10:21 AM   #2
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Have you tried to clean the contacts?
12-03-2012, 10:13 PM   #3
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If SDM works on your other bodies then it isn't the lens that has the issue - it's the K20D body. And as Anvh indicates, you probably have dirty contacts on the mount.
12-04-2012, 01:52 AM   #4
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No "clean contacts", pls! May be my English not good. Try to explain in other words:
1. Both bodies is perfect
2. 50-135 didn't work on both bodies.
3. When I close (isolate) by tearing tape one contact (there is two square for SDM on lens bayonet),
50-135 works on K-01 with SDM autoficus and so on, but not work on K20D.
4. ALL CONTACTS IS CLEAN
So, I think there are electrical problem with 50-135, but not SDM. Any ideas? Anybody have electrical diagram?

12-04-2012, 07:54 AM   #5
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What did Pentax say when you contacted them about this problem?
12-04-2012, 07:58 AM   #6
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QuoteOriginally posted by MPrince Quote
What did Pentax say when you contacted them about this problem?
Pentax say:

"Give me your money"
12-04-2012, 08:14 AM   #7
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QuoteOriginally posted by Olek Quote
Pentax say:

"Give me your money"
I asked a serious question. When you have a problem with a piece of equipment does it not make sense to contact the manufacturer for a solution? The people on a forum can only guess at what the problem and solution(s) might be. This may be fine for simple problems, but your problem does not sound simple. Getting help from the people who manufacture and service the equipment seems a better choice than soliciting opinions on the internet.

If it costs money, it costs money. Photography is not a cheap hobby.
12-04-2012, 12:01 PM   #8
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QuoteOriginally posted by Olek Quote
No "clean contacts", pls! May be my English not good.
Hey it's hard to diagnose the problem without even seeing the damn thing or know what you're preciesly talking about.
So we start at the simple things, it's off little use that you tear your lens open and then find out that your contact was simply dirty right?

So yes this is going to be a step by step thing till you find a solution but by the sound of it you tried all the reasonable sane things already.


The problem is with the identification of the lens, that's 1 pin on the body and the lens.


Either that contact is faulty, the wiring or the chip itself inside the lens.
SDM and the rest of the autofocus is fine, the problem is that the lens isn't telling the body that it has AF.


You can unscrew the backside of the lens to access the chip.
Search on google and you will find it, i won't point you to it, i don't want to be blamed when you mess it up

12-05-2012, 02:34 AM   #9
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Well, may be there some misunderstanding. All contacts clean, right! You give picture of bayonet, thanks. But on this picture is not two separate contacts for SDM. This square contacts are separate of bayonet contacts, and place above and near the rear lens. So when I seal, steak up, isolate one of this contact, SDM working on
K-01(so body receive information that lens AF SDM), but not working on k20D . You consider that this can be due lens chip? Can I test it through bayonet by tester?
Of cause I can disassemble lens till the very end, no problem. But first I wants understand the problem. Cause problem is chip, I am not sure, that I can fix it without service.
12-05-2012, 12:28 PM   #10
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Now i can yell at you for not reading my comment correctly

OKay will word it differently:
- SDM contacts are only for power, so the camera send a current through those contacts to drive the SDM motor, it's not used for communication as far as we known.
- The contact that is shown in the images IS the contact that provides the SDM information you're talking about

You got me now.

The other contacts shown in the image are used for the aperture settings and nothing more, they are "dumb" contacts so to say like morse code almost.
So if you seal one of those contacts you're changing the minium/maximum information aperture of the lens, nothing more.
The focal length, auto focus and the Lens ID is send through the contact shown in the image.
12-05-2012, 01:47 PM   #11
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QuoteOriginally posted by Anvh Quote
Now i can yell at you for not reading my comment correctly

OKay will word it differently:
- SDM contacts are only for power, so the camera send a current through those contacts to drive the SDM motor, it's not used for communication as far as we known.
- The contact that is shown in the images IS the contact that provides the SDM information you're talking about

You got me now.

The other contacts shown in the image are used for the aperture settings and nothing more, they are "dumb" contacts so to say like morse code almost.
So if you seal one of those contacts you're changing the minium/maximum information aperture of the lens, nothing more.
The focal length, auto focus and the Lens ID is send through the contact shown in the image.
I seal SDM contacts, one of them. If you look at any SDM lens bayonet you see TWO SQUARE contacts. This contacts used for Power Zoom before, now for SDM. I seal (isolate) one of this! ... Not aperture contacts, which are round....
12-06-2012, 12:55 PM   #12
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Where do i say that you seal one of those?
I said if you seal
12-06-2012, 02:36 PM   #13
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Hi Olek
Try to measure resistance with ohmmeter between those square contacts, they may be shortened. Then check resistance between each square contact and the metal body of lens. Those values may clear up the “foggy” situation with your lens.
Cheers
12-07-2012, 07:42 AM   #14
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QuoteOriginally posted by pavpen Quote
Hi Olek
Try to measure resistance with ohmmeter between those square contacts, they may be shortened. Then check resistance between each square contact and the metal body of lens. Those values may clear up the “foggy” situation with your lens.
Cheers
Thanks! Will try. Good idea.
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