PDA

View Full Version : Canon 20D - replacement of shutter release switch


Doug Kerr
July 12th, 2007, 09:56 AM
The shutter release switch in the EOS 20D can fail completely or misbehave.

Two somewhat subtle misbehaviors (both experienced here) are:

- The half-press contact closes early (starting AF and AE) during the stroke of the button before the switch has made its first snap. This is not usually a serious functional problem on its own, but may be a hint of other trouble (current or to come). (A clue to this is that the pertinent AF point indicator will flash before the first snap.)

- When beginning to complete the switch stroke from half press to full press, the half press contact opens briefly and recloses. This makes the camera think you have fully released the button and then started over, and so AF and AE are taken again. (A clue to this is that, when you go from half- to full press, the pertinent AF point indicator will flash again.) The consequences include:
-- Focusing on the wrong target (when the focus-and-recompose technique is used)
-- Delay of the actual release of the shutter

Those with experience in working with electronic parts and assemblies can readily replace the switch. Removal of the front, back, left side, and top covers of the camera are required, but this is all straightforward (once you know where all the hidden screws are and in what order things have to come off).

I have just released to my technical information site, The Pumpkin, an article entitled "Canon EOS 20D - Replacement of the Shutter Release Switch", available here:

http://doug.kerr.home.att.net/pumpkin/index.htm#20D_SRS

It completely describes the disassembly procedure required to access the switch and the replacement of the switch itself, with extensive photographic illustrations.

It also gives information on the procurement of a replacement switch from Canon Parts in Jamesburg, N.J.

Before undertaking such a repair, please read the article thoroughly and then decide if you have the necessary skills and experience for this project.

Asher Kelman
July 12th, 2007, 01:14 PM
Doug,

I'm so impressed with your gutsy work! This should empower those who are technically savvy. Moreover, your work demonstates that these serious problems are amenable to repair outside of the official centers.

Now I hear that Will Thompson has replaced or is about to replace an entire shutter!

Asher

Steve Saunders
July 25th, 2007, 02:29 AM
Great tutorial Doug.