Canon 40d – no USB connection

Without USB connection is not possible to work with the service software, so no fault codes, no programming – nothing what You need to set up a camera.

One of my clients has bought a used mainboard for a dead 40d. After installing it, the computer was not able to build up the connection. With the normal EOS utility was no connection, and the computer was displaying: unrecognized USB device…. Computers are sometimes getting crazy – so I checked the USB port with my service 40d. Everything was perfect. OK, than the mainboard is bad. Without programming, adjusting the AF has NO SENSE to mount on another mainboard in a camera. The 40d was working, the AF was of course unusable. After disassembling/assembling many times, I decided to ship back the PCB to the seller. As a last chance, I tried to connect it to the PC – this time in another USB slot. And the camera was recognized, EOS utility was working. The service software too. Excepting some functions, where the software was blocked. I changed back to the other slot – not working. Ouuups.

In the other PC – not working. What can be different in too USB slots? I have a cheap USB hub on my desktop. I tried that one.In this case, the camera was working on all slots – and more than this, it was no problem with the service software, all functions were OK. The explanation is simple: the cheap hub works only in   full speed mode, and forces the PC to use this protocol.

File:USB Icon.svg

A USB 2.0 device is normally high speed capable, but works in both. So, if the connection was forced by the hub to be slower, the camera was communicating without errors.

OK, the solution is, to connect through the hub. But what is the reason?!?!?

I disassembled the mainboard (it has been sold as used part – not as repaired), and I have found the following:


The USB socket on the PCB has been repaired in a very strange way – on the socket there is a hard black silicone glue – no possibility to take it off. I don’t know, if the silicone is not isolating enough, or there is any other problem under it. The big problem is, that the seller has forgotten to tell us about this tiny fact.

I worked many many useless hours (in fact, many days) because this. Now the camera works – I hope, not only for a few days…

Anyway, for knowledge no sacrifice is too much 🙂

About canonrepair

Ruzsa János. Amatőr fotós, Canon DSLR váz. Amateur photographer. Canon DSLR user.
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3 Responses to Canon 40d – no USB connection

  1. Gabor says:

    But in this case I think we can say officially that this PCB is useless because with USB 1 speed it will take hours and hours to retrieve pictures from the camera.

    • canonrepair says:

      Yes, we could say – but it is not possible. To send back the mainboard would be a lot of money and time. For the enduser the problem is only with the downloading of the pictures – I asked her, she uses always a cardreader.
      So, the mainboard will remain in the 40d – and the seller will be informed about this whole thing.

      • Gabor says:

        Yes, cardreader could be a solution. Hope you can get some discount, if you bought it on ebay with paypal you have good chances.

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