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08-02-2012, 04:58 AM   #1
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Disassembled Tamron 70-300 AF LD and now it's not working

Hello,
i bought my Tamron on ebay, but didn't see that it has a defective aperture. The problem was that the ring, which has to be rotate to open the aperture was deformed, so the spring was too weak to rotate it back to the close form. I disassembled the first 4 screws and a ball and a small spring were falling out. As i figured later, the ball came from aperture ring it has another bigger spring for pressing. But what i can't figure out is the place where the other small spring came.
Now i repaired the metalic ring, so the ring comes back to closed form, but the aperture of the lens still doesn't work Before my repair it seemed like it was always open, now after my repair it seems like always closed and i can't set something on the camera, it shows F=4 and it blinks to F=22 after release.
I don't know what i did wrong, because now it should work. Maybe it has something to do with the spring, which i can't identify.
I hope someone can help me.
I added photos of the lens together with the spring.

Dimitri

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08-02-2012, 06:37 AM   #2
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I can't edit my messages and i have some updates. This would be my updated message, i think now is something wrong with the electronic. My other kit lenses working fine on my K-X.

Hello,
i bought my Tamron on ebay, but didn't see that it has a defective aperture. The problem was that the ring, which has to be rotate to open the aperture was deformed, so the spring was too weak to rotate it back to the close form. I disassembled the first 4 screws and a ball and a small spring were falling out. As i figured later, the ball came from aperture ring it has another bigger spring for pressing. But what i can't figure out is the place where the other small spring came.
Now i repaired the metalic ring, so the ring comes back to closed form, but the aperture of the lens still doesn't work The aperture now is always closed, but if i use the lens on camera in manual mode(switch button on the camera) it shows F=4 and it blinks to aperture which i set often, but the most photos are made in F=4, somehow i managed to do F=13 and F=14 photos. In the Auto mode there is no blinking, it's always at F=4 and i can't set anything else. I tried it in M and Av modes.
I don't know what i did wrong, because now it should work. Maybe it has something to do with the spring, which i can't identify.
I hope someone can help me.
I added photos of the lens together with the spring.

Dimitri
08-02-2012, 07:30 AM   #3
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If the spring has little loops on the ends, it could be a retention spring that should hook onto two tabs. This would pull the aperture back open when the aperture lever isn't depressed. If it doesn't have those loops, i'm really not sure. I suppose that spring could be a tensioner (as a push) behind contacts. Can you post a picture of the spring?
08-02-2012, 07:46 AM   #4
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thanks for your reply
It shouldn't be the spring of the aperture. I post 2 photos. 1 photo with a red circle, i don't know the purpose of this thing.
I think there is something wrong with the contacts, but i don't know which ones, i tried to rub them with a finger, but still no effect. I also don't know how could i damage there something, because i repaired only the mechanical parts.

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08-02-2012, 07:53 AM - 1 Like   #5
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Ok, I've taken a tammy apart that had this. That boomerang shaped thing with the nob on it actually slides along a plastic rail on the aperture ring - see how that plastic rail that your circle intercepts looks like a ramp? There should be a piece on the underside of the lens mount that helps push that pin against the rail. I'm not 100% that the spring is involved in this set of components. I took apart a 28-200 to remove some fog from rear elements (turns out they're sealed) and had to tweak this area a couple times to get things working right. I'm at work and don't have it with me, so I can't give you better info than this for now.

So, again, I think that nob on that boomerang needs to be back against the curving plastic ramp along the aperture ring, and it's held there by a piece on the under side of the lens mount.
08-02-2012, 08:19 AM   #6
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Thanks.
I see, so this is just for manual set of the aperture. It works only if the boomerang is down, else aperture can't be closed.

Unfortunally i can't find anything about flashing F with changing numbers, everything i could find is flashing aperture with --.
I tried to move the lens a bit off the camera, that the aperture still has numbers on the lcd, then the flashing stopps and i can set an aperture from 1,8 up to 32, what is wrong, because the lens allows only F4-22. If i make some photos then the aperture stays at open and doesn't change.
08-02-2012, 08:29 AM - 1 Like   #7
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I'll take my lens apart again when I get home (that aperture ring and bearing are royal pains). I think that spring may push a contact out on the mount, and you may have dropped that pin without knowing it, or the pin is still in place but without the spring isn't making consistent contact.

Actually, I just remembered/figured it out. See the red circle. I'm fairly certain that you should put the spring there. Double check to make sure it isn't bottomless beforehand

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08-02-2012, 08:46 AM   #8
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Hahaha great, now it works Thank you a lot i had this idea too, but then i didn't believe that it has something to do with it, because there was no hole and this was actually the point

08-02-2012, 08:47 AM   #9
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Glad I was able to help. Happy shooting!
08-02-2012, 08:58 AM   #10
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Thank you
One really small issue remains: sometimes the smallest aperture i can set is 5-7,1 instead of 4-5,6. After some photos it goes again to 4-5,6. But this is a small issue now
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