I repaired only 5 pieces of 7d cameras. Some of them were giving no sign of life at all, others sometimes worked normal, sometimes not.
But there was one common point in all of this cases: there was a free screw somewhere in the body.
In 4 of this 5 cases the problem was with the screw from the bottom flash board. You have to fix them with some Loctite 243..
If You don’t see the screw, the first place where to look is the motor – the magnet will catch the flying screw after a certain time.
And before taking in parts a camera, check the battery voltage. In may case it was practically 0 V.
DIGITAL CANON repair blog 
Hi nice readingg your blog
Hi Im just trying to figure low battery blinking (on/off doesnt matter) on my 7D and disassembly proved no loose screws inside. (all firmly “loctited”). Could this behavior mean even bad flash board or it is mostlikely DC/DC board?
unfortunatelly most probably the DC DC board.
So I was attempting this repair last night, and I may have done some serious damage to the camera. I was attempting to remove the bottom plastic piece, and I was doing so with a flat-bladed screwdriver. I believe that I may have touched the screwdriver blade to one of the flash capacitor leads, and the capacitor most likely shorted against the metal bits of the case and discharged. There was a bright flash of light, some sparks, and a bit of smoke.
The camera will not turn on, and the top display is reading the dreaded Err 40. I’m hoping that all I need to do here is replace the flash PCB. However, in your experience, could anything else have been damaged? Would I potentially need to replace the DC/DC Power PCB as well?
as in the capacitor are 310 volt, can be anything. try the bottom pcb at first.
Hey nedwilson1, did you ever get this issue resolved? Im experiencing the same problem. was the flash PCB board only what was needed to be replaced?
Replacing the Flash PCB was indeed the solution to the problem. I found a replacement on eBay for around $70. It took about two hours to swap it out, using a combination of guides I found in iFixit.
Nice post. I’m facing exactly the same issue on my 7D. The loose screw was felt and stuck to the motor magnet. I unmounted my 7D using this great video : https://www.youtube.com/watch?v=DQaejgJM1Rc. The screw is back in its place but unfortunately, my 7D does not power on anymore. Even with battery fully charged. Do you have any suggestion ?
unfortunatelly this means 99% that your bottom pcb (with the flash capacitor) is blown. approx 80-100 usd
I appreciate your blog. I used it as a reference to fix my 7d that got wet in fresh water. I had it in an under water housing that got flooded. I took the battery out right away, but couldn’t dry it until the next day. I put it in a vacuum chamber for about a half hour. This completely removed all the water, but it wouldn’t power on. I disassembled it and found slight corrosion in the connectors of the bottom board and the main board. Also on the surface of both of those boards. I cleaned the corrosion off with a soft toothbrush and reassembled. Works great now. Thanks for the inspiration to fix it myself. I called a repair place and they said it wasn’t even worth trying to repair.
Underwater housing – the best way to kill a camera 🙂
I’m sure they would not pay for the damage caused by it…
the problem with the vacuum-drying is, that at first You should rinse thoroughly with destilled water, and then should come the vacuum.
A screwdriver is a MUST in the camera bag.
that worked for me, thank you!
thanks for the feedback!
was it before a failure or after?
Great article! We are linking to this great content on
our website. Keep up the great writing.