Canon EOS 40D Instruction Manual page 176

Troubleshooting Guide
Live View shooting is not possible.
When using Live View shooting, use a CF card (a hard disk-type CF
card such as MicroDrive is not recommended). A hard disk-type CF
card requires a lower temperature range for operation than with
normal CF cards. If the temperature gets too high, the Live View
shooting may stop temporarily to prevent damage to the card's hard
disk. When the camera's internal temperature decreases, the Live
View shooting will be able to resume. (p.107)
The built-in flash does not fire.
If you shoot continuously with the built-in flash at short intervals, the
flash might stop operating to protect the flash unit.
Image Review & Operation
The image cannot be erased.
If the image has been erase-protected, it cannot be erased. (p.123)
The shooting date and time displayed is incorrect.
The correct date and time has not been set. (p.41)
No image appears on the TV screen.
Make sure the video cable plug is connected all the way in. (p.122)
Set the video OUT format (NTSC/PAL) to the same video format as
the TV. (p.39)
Use the video cable that came with the camera. (p.122)
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