EOS 700D external trigger overvoltage repair

[Anonymous]

Hi, I was attempting to make a DIY external trigger for my EOS 700D and accidentally overvoltaged the 2.5mm trigger port (dumb of me, I know). Now the camera constantly takes photos as soon as it's powered on. I think I shorted something out, as the port is now a dead short when it used to be an open circuit.

I took apart the camera and removed the board with the port on it:

I tested the port with the board unplugged from the camera and it's still a short, which makes me think the problem is within the board itself. However the camera still constantly takes photos when the board is unplugged, so there could be some damage to the main board too.

I'm not totally sure how to proceed now. Ideally I'd like to get the external trigger working again, but I'd also just be happy with the camera not constantly taking photos. Does anyone have any experience with this issue, or have a schematic of the board in question, or something? Or is there a way to disable the external trigger?

[mgonidec]

Hi! I have a camera on repair from a user that used the snap port. Seems to match your description. Can you confirm which diode you removed? the one below the snap port on the picture? seems a bit burnt actually!

[Anonymous]

I removed this one, directly below the port.

[mgonidec]

I can confirm the following:

- I had a 700d that had gone crazy. It would snap a picture right upon powering it up and would not take more when pushhing the trigger button. It would take a shot from the menu button when pushing the trigger. Using the touch screen also worked. 

- The user told me he used the snap port, which somehow made me find this lucky thread.

- I tested the diode indicated by LostXOR and it was indeed falty. I removed it!

- Everything seems to be back to normal. I have not tested an extrenal trigger connected with the snap port for now though.

Any clue what the purpose of that diode actually is?

[Anonymous]

My hypothesis is that it's to protect the port, maybe in case someone plugs in a 2.5mm audio cable and plays a signal through it. Clearly it's not sufficient to protect against everything though (or maybe it's sacrificial, and failing is intentional).