Question about Canon EOS 400D / Rebel XTi Digital Camera

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Camera doesn't turn on - Canon EOS 400D / Rebel XTi Digital Camera

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  • gwdrisco Jul 23, 2009

    Thank you. I feared as much and did send the camera in for expert repair. My follow up question.: What causes the malfunction? Is it improper care and handling of the camera? Many thanks.



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Such symptom indicate a malfunction on the DC/DC voltage converter circuitry, and the camera has two of them located in different boards.

In order to perform a correct diagnostics and repair of it, it is necessary to open such camera and perform it by a qualified camera repair technician.

If it's under warranty, I do recommend you to send it back to make valid the warranty.

If not, then you have the options of pay for its repair, or do it yourself if you are willing tgo open it and perform some basic diagnostics of the failure. You will need tools to do it, which includes the usage of a soldering iron.

Best regards,

Posted on Jul 23, 2009

  • Jaime Gutierrez Jul 23, 2009

    Without perform a throughly analysis on this particular camera, it is hard to point out what happened to cause a failure.

    I can only especulate about it:

    1. Particular conditions of usage and settings.

    The internal boards have electronic components and small fuses for each important circuit of the camera. If some particular conditions and settings cause that the electrical current through some fuses or components is exceeded during few mili seconds, such components are opened and need to be replaced.

    Sometimes such problem happens once and never happens again after being replaced such components.

    This is caused due to a marginal electrical design of the circuits.

    Other example of it, is that you have in Auto focus your camera, and at the moment of press the shutter switch, accidentally you touch or prevents the lens to auto move, causing that is needed more electrical force (current) to move the lens, and momentary the current limit is exceeded, opening the components.

    2. Infant Mortality of semiconductors. Name for the phenomenon where semi-conductors and integrated circuits are defective due to quality of materials and manufacturing process issues. It is well documented, and all manufacturers of electronic devices have to consider it during the quality goals of their products. Usually the manufacturers screen such failures and try to capture all of them in their facilities, but a small percentage of such failures escape their testing and screen process. I don't know excatly what percentage is in the case of Canon for this model XTi, but the industry standard is 0.1 - 1% of the production that fails early with the customers.

    Maybe you were part of such statistics.

    3. Manufacturing issues that cause an early failure of the camera.

    4. Moisture or humidity that causes an internal corrosion problem with time, until a part of the circuits fails.

    Bottom line, unless an user mis use the camera (dropping it, having water over it, etc), most of the reasons are not under control of such user but are conditions that have to be considered by Canon at the moment of design and manufacture their cameras.

    Trying in answer why your camera failed, means to fix it, and then simulate different conditions and measure the circuits. It a job for a diagnostics laboratory.

    If you investigate about the percentage of failures of almost brand new SLR digital cameras, you will be surprised that Canon is in the top or second with such kind of failures. Something tha canon had to addressed since years ago to improve the quality of their products.

    Maintaining the perspective, image that your camera is a particular automobile, that is failing, where other brand of cars have better quality/price relationship than your's.

    I hope this help you to understand that electronic devices sometimes fail with no apparent reason but a poor quality or poor design, which we as end users, we know nothing about it.

    As final note, I bought in ebay two years ago a broken Canon XTi 400D camera. The reason that won't power on was two open fuses in two different boards. What happened? I don't know, but since I bought it cheap and I was able to find out what parts was necessary to replace and fix it, I didn't care about it. Since I repaired it, I had no problems with it, and I am using it very heavily since then.

    Best regards,



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