17-85 err01 fix (aperture flex cable exchange)

Started Jan 28, 2012 | Discussions thread
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PhotonFiend
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17-85 err01 fix (aperture flex cable exchange)
Jan 28, 2012

First a description of the problem:

During a photo shoot I was very disappointed to see "err 01" on my screen of my 40D. After resetting the camera I got a few more pictures out of it, but the error kept reoccurring. After getting home I played around and and managed to narrow the problem down. If the lens was at the wide end and the aperture was stopped down at all the error would occur every time. I could also push the aperture preview button and could see the aperture flutter and close to a different width with each push (no matter what the setting on the camera). If I zoomed the lens then everything worked fine.

Canon estimated $200 for the fix!!! I thought that was excessive so looked for alternatives.

I found several people on the internet describing similar situation with instruction on a DIY fix. The ones I found most useful I refer to here:
1) http://www.youtube.com/watch?v=qml1ukgm58Q&feature=related

2) http://canonrepair.wordpress.com/2011/11/04/ef-s-17-85-is-aperture-change-as-simple-as-possible/

My Fix:
1. Following ref1 I just popped the black cap off the back of the lens.
2. remove 2 tiny screws that fix the lens contact to the mount.
3. remove 4 screws around the silver mount, remove the mount
4. remove cable attached to outer casing and remove casing.
5. remove remaining cable from circuit board.
6. remove 1 screw from circuit board and remove the circuit board.

7. remove 5 screws from outer black plastic ring surrounding back lens. remove ring

note CAREFULL of the focus distance sticker, its very sticky and will crinkle and stick to the inside of the lens.
8. remove rubber zoom cover.
9. remove black square sticker
10. remove 1 screw under sticker and remove the metal fingers.

11. remove 3 screws with brash bushings in slots around exposed zoom ring.
12. take out outer outer barrel.

note here I deviated from most instruction by NOT removing the front lens

13. remove too & middle inner barrel screws: 3screws+3 white bushings holding the IS unit (careful it will become loose and knock around inside) and 3screw+3 bushings holding the focus element.
14. the inner lens set will come out now by pulling the back lens straight out.

15. now the aperture is exposed inside the bottom of the barrel. remove 3screws+3 bushings holding it in place.

16. remove 1 screw holding the flex cable clip at the top and the aperture will lift out by the flex cable (this is the problem part).

17. replace the cable and reassemble.

The bad cable is on the right

Now I did not see any obvious damage on the cable like some. but the cable is pinched VERY tightly by the clip. When I replaced it I did not put the cable in the cable pinch as before, just taped it and looped it.
18. reassemble

A couple of afterthoughts.

when i got it reassemble everything worked including aperture EXCEPT focus! I could here the USM moving into position but focus would not change. there is a long fork that the USM swings that attaches to an arm on the focus element. this I did not get back in place quite right. I got it right the second time so watch out.

also i nearly stripped one of the zoom ring screws by using the wrong driver. it took me an extra day to hunt down a driver that would get this screw out. I should probably replace it, but its holding just fine ATM.

In step 7 apparently there is supposed to be 6 screw, but I only had 5!?!? I was very careful about this, and sure enough I checked my pics of before disassembling and there is one missing. hmmm...

Parts:

http://www.ebay.com/itm/150594148894?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

the replacement part cost less than 4 dollars. its looks better than the original. the original has VERY thin traces running the length of the cable. The replacement widens the traces immediately following the aperture and run the full length of the rest of the cable. no doubt more robust.

I hope some find this interesting and perhaps helpful.

Canon EOS 40D
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