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06/14/2008 06:22:09 PM · #1 |
My Problem (random external flash bursts):
Canon 20D with 430EX or 580EX flash and somewhat heavy lens attached (70-200 f/4L IS), the external flash would randomly emit a 1 second flash burst. Very annoying. My first thought was the lens mount electronic connections were faulty.
The Cause (sticky DOF button):
The 20D uses the "Flash Modeling" feature of the 430/580EX speedlight to fire the flash at 70 flashes per second for about one second when the camera's "Depth of Field Preview" button is pressed. My DOF button was sticky, and the heavy lens would cause the button to press the internal contact. I found that even with a light-weight lens, if I pressed down on the top of the lens, the flash would go off. Using a magnifying glass to examine the button, I could see what looked like dried skin oil (otherwise known as white stuff) where the button enters the body. If I flicked the button with my fingernail, the flash problem would go away for a while, but eventually come back.
The Fix (clean the button):
I tried using Eclipse fluid to clean around the DOF button, but that did not help. The white stuff was stubborn. So I used a 000 jewelers phillips screwdriver and the instructions on how to remove the 20D faceplate found here (see page 4 and the pictures on page 9):
//doug.kerr.home.att.net/pumpkin/20D_Shutter_Release.pdf
With faceplate removed, I was able to get to the button by removing the yellow tape shown here:
//www.dpchallenge.com/image.php?IMAGE_ID=688687
Cleaned the button and the faceplate hole with a Q-tip and lens cleaning fluid, used the same tape to hold it in place, put the faceplate back on with the 7 screws, and the problem was fixed.
My only concern during the operation was that the 7 screws are 4 different sizes - I'm glad I organized them so I could remember which holes they came out of.
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06/14/2008 11:14:21 PM · #2 |
You are a braver man than I! I was a mechanic for 15 years and took lots of things apart and put them back together. My first job (as a teen) was in a TV repair shop (back when TVs got repaired). I tried to work on a laptop a few years back and had a hell of a time getting it back together - so much so I'm fearful of taking anything electronic or small apart ever again!
Glad you got it all working. I suppose the design is teh same on 30 and 40D bodies too, huh?
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