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RC USB Failure - Preliminary Failure Analysis and Fix

Discussion in 'Pro/Adv Discussion' started by atestani, Mar 31, 2016.

  1. atestani

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    Many people have had RC USB port “failures” and I am (was) one of them. Having had a lot of experience in developing and manufacturing electronics, I decided to look for the root cause of these failures before I sent my RC back to DJI on the RMA they provided and wait 1-3 weeks for the RC to be returned. At this point, I no longer have to send many RC back as I found the problem and easily fixed it.

    It is interesting that in talking to two different DJI reps, neither had heard of RC USB failures as a widespread problem! In searching for my own solution, I came across a large number of posts with people having the same issue but the only resolution was to either send the RC back for repair or upgrade to the HDMI module.

    So… basically the root cause of the problem seems to be a design error where the wrong USB connector was specified or manufacturing substituted/used the wrong type of USB connector. The small USB interface board is designed and constructed with all SMT (Surface Mount Technology) components. SMT components are typically soldered to the board using a small amount of solder paste stenciled onto each connection point, components placed in position, and reflowing all the solder paste joints at once in a reflow oven. The issue is the USB board has a footprint for the large USB connector that is for a TH (Through Hole) part yet is was soldered to the board as an SMT part. This mismatch causes a very fragile set of solder joints which eventually will become intermittent or fail completely, as in my case.

    Note that the typical “tests” for a bad USB port is to see if the attached phone or tablet is charging and the DJI GO app connects to the RC. There are 4 pins on a USB connector: VUSB (+5V), Ground, Data + and Data -. If the bad connection is on VUSB and/or ground the attached device will not charge. If either of the Data lines are not connect the attached device will not connect to the app. In my case, the device was charging but there was no USB communication with the app (or memory stick, etc. for upgrading firmware).

    I repaired my USB board is less than 5 minutes simply by manually reflowing the solder joints on the connector.

    I am not totally sure of the type of USB connector on the board and would like to investigate this problem further. To do this I would have to remove the USB connector and inspect it. I do not want to do that for fear of voiding my warranty. If there is anyone who had this problem and “fixed” it by upgrading to a HDMI module, I would be interested in evaluating the old board. If you have such a board and are willing to part with it, please start a private conversation with me so we can make arrangements to get me the board.

    Once I am sure of my analysis, I’ll put together a little report and instructions for fixing modules if anyone wishes to do so.

    Thanks

    Al
     
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  2. sonof40

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    Nice work and a good project.
     
  3. Oso

    Oso

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    Great post. Thanks.

    It's hard to imagine that the DJI reps had never heard of the RC USB failures. Either they are not being truthful or they are really just clueless. Both are very sad.
     
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  4. PEEFA

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    Neither of the two rc I have used have charged the device connected android and iOS.


    Sent from my iPhone using PhantomPilots mobile app
     
  5. atestani

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    Good chance the VUSB and/or ground connection is bad.
     
  6. Trackman1

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    I thought IOS did not charge and Droid does.
    Just going by what I have read in here.
     
  7. alokbhargava

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    I have long electronics design and assembly experience. I will analyze my board and will give you a feedback.
     
  8. Dacon Productions

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    Would be nice to have the iOS pads charged by the RC.
     
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