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Fixing Tamron Adaptall P/KA Adapter
Posted By: Class A, 02-11-2009, 04:18 AM

Do you have a problem with a Tamron Adaptall PK/A adapter whose "A" functionality is not available or only if you do not completely mount the adapter to the camera, i.e., twist it back a little after mounting?

Chances are that it does not index on the body too far clockwise and that you can fix it within a minute.

The culprit may be one of the three screws which are fixed using a glue that electrically insulates them from the camera mount. If this is the cause of your problem then removing the glue from the end of the screw which is closest to the other electrical contacts (i.e., the top rightmost in the image below), e.g., with the tip of a knife, will make establish contact to the body mount again. This made my adapter work and I'm indebted to marvintm whose post "Re: How to fix bad Tamron KA mount" provided me with the solution.

However, since the illustrating images from his post are no longer available, I initially had trouble finding the screws. I finally found them and below is an image showing the location of the screw ends.

Contrary to marvintm's description, the glue on my screw end was not easily discernible by a light blue/green colour. I just lightly scratched on the screw end just in case and the adapter now works like a charm.

Good luck!

P.S.: This explanation of the KA-mount contains all the information required to know for which lens (minimum and maximum f-ratio) the pins should be shorted to the ground by the adapter. This should help troubleshooting if the camera doesn't use the correct aperture range. Note that the adapter does not fully support lenses with a minimum f-ratio slower than f/4 if the maximum f-ratio is f/22 and there is an "AE" setting or f/32 and there is no "AE" setting. Alternative explanations of contacts are Mark Roberts matrix metering mods page and this detailed explanation of the adapter contacts.

P.P.S.: You may want to try to convert a P/K adapter to one that supports P/KA functionality for a specific lens.

Attached Images
 


Last edited by Class A; 09-15-2009 at 06:50 PM.
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02-11-2009, 05:49 PM   #2
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Article approved and moved to the Lens section. Thanks for your submission!

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02-24-2009, 09:35 PM   #3
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Hi: My Tamron Adaptall-2 adapter was not delivering the actual aperture to the LED readout in the VF. The e-dials changed the aperture, but I didn't know from what to what.

In 60 seconds I removed the coating from the screw nearest to the 3rd contact and - voila - Av readings available!!

A Simple fix that works.
07-18-2009, 02:07 PM   #4
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thanks -- this just saved me ...

I just got a set of PKA adapters and 2 of them seemed to be defective; glad I looked here to see if anyone else had the same problem and knew how to fix it.

Thanks!

08-14-2009, 08:25 PM   #5
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Great post! Thanks

I thought I had just wasted money on a Tamron 70-210 46A.

BG
03-05-2010, 07:10 AM   #6
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Great post

Thank you! This post just made my day! I bought an PK/A adapter from ebay and waited for it to come all the way from Australia to Norway. And what happened? It didn't work....

But this post + a small knife solved the problem. It sure made my day.

I also noted that the glue did not have any coloring or blueish tint. Just scrapted carefully the surface and it did the trick. I do need to slightly twist the lens towards the open position after mounting it.

So now my 24mm f2.5 01B extended its life. Maybe the 103A should be given the same chance in life.
04-08-2010, 12:32 AM   #7
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Yes, sometimes we have to wonder what makes the Adaptall ticks? Thank you for a great article, Class A.

I do have one for my 28mm Tammy prime lens.
08-10-2010, 01:15 PM   #8
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THANKS! A big help.

09-23-2010, 02:04 AM   #9
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Purchased 2 of these adaptors along with lenses months ago and neither worked until I read this post recently - now they both work.

Thanks
09-23-2010, 04:42 AM   #10
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QuoteOriginally posted by kev.pride Quote
Purchased 2 of these adaptors along with lenses months ago and neither worked until I read this post recently - now they both work.

Thanks
Do they give the proper aperture values?
Despite my greatest efforts, mine would never show anything less than f/4
Everything else works though.
I guess I shouldn't complain, but it does bother me considering the price I payed for mine
09-23-2010, 05:27 AM   #11
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QuoteOriginally posted by JohnBee Quote
Despite my greatest efforts, mine would never show anything less than f/4
Did you try to wiggle both the lens on the mount (keep the mount release pressed) and the aperture ring (set it away from AE and back again, using middle positions).

If all the wiggling doesn't help, it might be that one of the pickup shoes inside the adapter isn't working. They are quite delicate little things and is possible that one of them doesn't make contact anymore.

You could use an ohmmeter to check whether the contacts on the lens mount show the correct conductivity for various adapter settings (see the explanation of the KA-mount in order to know what to expect).
09-23-2010, 05:42 AM   #12
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QuoteOriginally posted by Class A Quote
Did you try to wiggle both the lens on the mount (keep the mount release pressed) and the aperture ring (set it away from AE and back again, using middle positions).

If all the wiggling doesn't help, it might be that one of the pickup shoes inside the adapter isn't working. They are quite delicate little things and is possible that one of them doesn't make contact anymore.

You could use an ohmmeter to check whether the contacts on the lens mount show the correct conductivity for various adapter settings (see the explanation of the KA-mount in order to know what to expect).
Hi,

I did wiggle the lens(doesn't change).

And I did inspect the little wipers on the inside of the adapter. However... I can't remember if I tested them with an ohmeter. And if I did, I most likely didn't test for anything oiher than continuity. So there is still room for troubleshooting at that level I guess. The biggest issue is where everything seems okay in terms of contacts and parts go(as far as I can see). But that just means I haven't figured it out yet

I tried covering/shorting one of the pins on the mount which in turn changed the aperture value to f/2.8. However, I was never able to adjust it using the adjuster screw and slide mechanism inside the adapter cover. Which may also be a sign that something isn't working right at that level.

PS. when I got the adapter and opened the cover, one of the sliding contact wipers was completely squished. The seller tried to convince me that the adapter worked fine when he had it, but you know how that story goes... classic eBay song and dance
12-14-2010, 05:07 PM   #13
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My one PKA won't go below f/4 unless it's about 1mm before the lens locks to the body.

No other cameras to test with at the moment.

Finish scraped down to brass around pin #3. Works properly down to f/2.4 when not locked to the camera. Since it works, I know the internals are good.

What could it be?
12-14-2010, 06:25 PM   #14
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QuoteOriginally posted by ryan s Quote
My one PKA won't go below f/4 unless it's about 1mm before the lens locks to the body.
What lens are you using the adapter with? Did you not the following line in the article?
"Note that the adapter does not fully support lenses with a minimum f-ratio slower than f/4 if the maximum f-ratio is f/22 and there is an "AE" setting or f/32 and there is no "AE" setting. "

QuoteOriginally posted by ryan s Quote
Works properly down to f/2.4 when not locked to the camera. Since it works, I know the internals are good.
What f-ratio does the camera show when the adapter is properly locked into place? If it is "--" then the "A"-pin on the mount doesn't make contact. If you are getting f-ratios but only >= f/4 then it seems likely that the adapter doesn't index correctly. Not sure how to fix it in this case.

Last edited by Class A; 12-15-2010 at 01:51 PM.
12-19-2010, 02:21 PM   #15
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Gah, thought I subscribed to this thread...

I'm using the SP 90mm f/2.5 macro. I also have another PKA that works perfectly with this lens. It does have the AE f/32 setting. Without the 01F teleconverter, it shows f/2.4 as max aperture...with, f/2.8.

The "broken" adapter shows f/4 as max aperture when locked on the camera. With the teleconverter, it still shows f/4.
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