# EFS 17-85 Re-build



## Philshoz (Jun 14, 2014)

Hi Forum, first post here, hope you can help please.

I recently bought a 40D on ebay France and the guy gave me an EFS 17-85 free which was showing an error 99.

I sourced a new diaphragm unit and installed it yesterday, felt very pleased with myself. However, it now works but only in manual mode, AF will not register a reading.

Anyone had the same problem? Anyone have a solution please?.

Thanks in advance.


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## dgatwood (Jun 14, 2014)

Philshoz said:


> Hi Forum, first post here, hope you can help please.
> 
> I recently bought a 40D on ebay France and the guy gave me an EFS 17-85 free which was showing an error 99.
> 
> ...



When you say "will not register a reading", are you saying that the focus confirmation works in manual mode, but the autofocus hunts? Or are you saying that it doesn't move at all?

Regardless of your answer, the first thing I'd do is check the contacts on all the ribbon cables where they plug into the main lens board. Make sure the cables went in straight and went in far enough to make a proper connection. Then, I'd clean the contacts on the main lens board where it connects to the camera. Finally, I'd ensure that the main lens board contacts are sticking up high enough to make proper contact with the camera's contacts. I don't remember how those bits are built, so I'm not sure what (if any) adjustment is possible there.

BTW, I thought a stuck aperture usually resulted in Err01, not Err99. Is the aperture working correctly now if you stop the lens down all the way?


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## Philshoz (Jun 14, 2014)

Thanks for the speedy reply there.

It was giving an error 99 when I tried to use it the first time when it arrived with the camera, same thing on my 600d and another 40d.

Now it just searches for a reading in AF and doesn't make that focused sound.

It crossed my mind about those pesky flat cable connections, in particular the wide one. I'll have another crack at it and get back with the results.


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## Valvebounce (Jun 15, 2014)

Hi Phil. 
I rebuilt mine, do you have the ability to focus manually, as in you are actually able to focus it not just turn the ring on the outside? I missed the engagement of the focus (or was that the zoom) lever the first try at reassembly, fortunately I checked before fitting any more bits! :
One of the videos I watched mentioned a component on the circuitry that once touched is screwed, don't know the truth, didn't want to find out! The tea strainer that is my memory tells me it was a component somewhat square in shape and a few mms in size, somewhere near the zoom focal length measuring contacts or the focus motor area?!?!?
Hope you didn't prove that theory right! 
A +1 on checking all the ribbons are making good contact.
If you do find the cause please don't forget to let us know what it was! 

Cheers Graham. 



Philshoz said:


> Hi Forum, first post here, hope you can help please.
> 
> I recently bought a 40D on ebay France and the guy gave me an EFS 17-85 free which was showing an error 99.
> 
> ...


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## Valvebounce (Jun 15, 2014)

Hi dgatwood. 
The failure mode most common to these lenses is a cracked ribbon, not precisely a stuck aperture, it just won't tell the body where it is at! Mine was on the 20D I bought, sold as a dead body, a quick check proved it was the lens giving err99, they do work ok wide open zoomed in or out, and stopped down at certain zoom settings, usually full wide but mine was very intermittent at other points.
Very pleased with mine now it is fixed. You have to make sure to straighten the ribbon cable guide/support piece so that it is not folding but rolling the new cable as you zoom.

Cheers Graham.



dgatwood said:


> BTW, I thought a stuck aperture usually resulted in Err01, not Err99. Is the aperture working correctly now if you stop the lens down all the way?


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## dgatwood (Jun 15, 2014)

Valvebounce said:


> The failure mode most common to these lenses is a cracked ribbon, not precisely a stuck aperture, it just won't tell the body where it is at! Mine was on the 20D I bought, sold as a dead body, a quick check proved it was the lens giving err99, they do work ok wide open zoomed in or out, and stopped down at certain zoom settings, usually full wide but mine was very intermittent at other points.



Yeah, I once rebuilt a lens with precisely that problem, though it wasn't a 17–85.




Philshoz said:


> Now it just searches for a reading in AF and doesn't make that focused sound.



But it adjusts the focus, right? Just no beep? Did this particular lens disassembly require you to unscrew the front of the lens, and if so, was the front glass attached to that front plate like it is on the original 18-55? If so, the lens might be failing to achieve sufficiently exact focus because you didn't get the front lens screwed in fully. I ran into that the first time I did a lens rebuild.


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## Philshoz (Jun 16, 2014)

well I tried but don't have the dexterity or patience.

I put it on a French site for 50€ and it sold in two hours.

Epic fail on my part.


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