Canon DSLR – mirror not working ERR20

WP_20151117_22_19_46_Pro

The camera was a 60d, but in fact could be a 40d, 50d etc. – any camera with two motors.

Symptom: mirror resting in upper position. when pressing the release button, mirror went down quick, then up an err20.

I suspected that the phase sensor gives a non real position. I disassembled the mirror gear.

WP_20151117_22_20_14_Pro WP_20151117_22_20_37_Pro 

WP_20151117_22_20_14_Pro_close

On he flex cable the sectors give the position through a metallic brush. I observed some dirt between two sectors. I checked with a multimeter, in resistance mode (NOT continuity).

Instead of the normal infinite resistance, I have measured this:

WP_20151117_22_22_51_Pro

Ouuuups. This could be the problem. I cleaned it, after that:

WP_20151117_22_22_46_Pro

This is the normal value. Be careful. As the phase sensor goes into a comparator, should not be a real short. Even a 1-2 kiloohm can be interpreted by the processióor, as a high or low level signal, as this contacts are connected to a voltage divider.

I assembled the camera – and it’s perfect.

The camera has been checked in another service too: they wanted to change the  whole mirror box…

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About canonrepair

Ruzsa János. Amatőr fotós, Canon DSLR váz. Amateur photographer. Canon DSLR user.
This entry was posted in 60d, Canon camera. Bookmark the permalink.

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