chipKIT DVDD not 3.3v -> replace D9 diode

afliuafliu Beijing, China
edited September 2015 in Cyton
[original thread titled: My OpenBCI 32-bit does not work recently.]

My OpenBCI 32-bit does not work recently. the phenomenon is that could not output any date, and even the blue LED light does not work.

Any suggestion on how to follow up debug or locate this issue?

Thanks,
-Anfeng

Comments

  • wjcroftwjcroft Mount Shasta, CA
    * What is your battery voltage? What type of AA cells?
    * Have you altered the firmware on the main board (or dongle), or is it still running default firmware.
    * Does your PC recognize the dongle (port shows up in device manager).
    * Is it possible the on/off switch on the main board is broken? Try the BLE position, which is currently equivalent with PC.
    * When did you notice the board stop working, what was happening just before that?

  • afliuafliu Beijing, China
    Hi William,

    thanks for the comments, please see the comments below:

    * What is your battery voltage? What type of AA cells?
    [Anfeng]: 1.5V (count: 4)

    * Have you altered the firmware on the main board (or dongle), or is it still running default firmware.
    [Anfeng]: No, still running default firmware.

    * Does your PC recognize the dongle (port shows up in device manager).
    [Andy]: Yes, the PC recoganised the gongle. And ports shows up in Processing GUI (COM8)

    * Is it possible the on/off switch on the main board is broken? Try the BLE position, which is currently equivalent with PC.
    [Andy]: I am not sure if on/off switch on the main board borken. I did switch to BLE position, but no lucky :-(.

    * When did you notice the board stop working, what was happening just before that?
    [Andy]: One week ago. I did not remember I did any specific action bofore. Just one day of one week ago, I connect the bettery, but the BLUE LED light did not work, then I could not get any date from the processing GUI.

    By the way, I have another OpenBCI 32-bit board, that one works well in the same environment. I mean use the same battery. Let me know if you have any suggestions that I can do some comparision testing with good one.

    Thanks,
    -Anfeng
  • wjcroftwjcroft Mount Shasta, CA
    With the main board powered on, do you see 3.3v between DVDD and GND header pins (top side of board near Open Source Hardware logo). Also measure your incoming TOTAL battery voltage (not a single cell).
  • biomurphbiomurph Brooklyn, NY
    @afliu,
    If you are able to verify that the OpenBCI board is getting power using the measurement described by wjcroft above, then I think the next thing to try is to re-program it. You can find a tutorial on how to reprogram the 32bit board here

    Please let us know if that helps
  • afliuafliu Beijing, China
    Willam,

    I measured the incong TOTAL battery volatage, the value was 6.11v. However, when I measure DVDD and GND header pins, the value was 0, not 3.3v.

    Looks like some component does not work :-(.

    Let me know if you have any suggestions to make more troubleshooting.

    Thanks & Regards,
    -Anfeng

  • wjcroftwjcroft Mount Shasta, CA
    Here's a similar thread where the protection diode failed. In your case it seems like it may be either this or the voltage regulator chip itself.

    http://openbci.com/forum/index.php?p=/discussion/403/board-not-turning-on-polarity-protection-diode-failed


  • afliuafliu Beijing, China
    Thanks William,

    Finally, I got diode D8 does not work, will replace it with new one.

    By the way, any idea why D8 does not work? Do we need to change to any type of diode?

  • wjcroftwjcroft Mount Shasta, CA
    Joel @biomurph may comment. Glad you isolated the problem.
  • biomurphbiomurph Brooklyn, NY
    @afliu,

    you can use just about any 0603 size diode to replace.

    Please verify that the problem is with the correct diode.
    Diode D9 is the input protection diode. 
    D8 is a diode that differentiates between PC and BLE switch (as yet unimplimented)

  • afliuafliu Beijing, China
    Thanks for the remider, Biomurph.

    However, I have someone replace D8, but no lucky. It is still does not work. Even volt is 0.01v.

    By the way, looks like D9 works well, the volt is around 5.46v

    Any other suggestions? Thanks
  • biomurphbiomurph Brooklyn, NY
    I don't understand this. 
    when you say 0.01V, is this the voltage drop across the diode? or is this the voltage output on DVDD?

    Also same for D9. Where do you see the 5.46V?
  • afliuafliu Beijing, China
    yes, 0.01V is the voltage drop across the D8. For the DVDD, the output is 0.00V

    what I said 5.46V is the voltage drop across the D9.

    Looks like I did not isolate the issue :-(.

    Anyway, Here is the some voltage detailsAfter I changed the D8, here is the details:

    GND ~ DVDD: 0.10 V
    GND ~ AVDD: 0.03 V
    GND ~ AVSS: 0.00 V


  • biomurphbiomurph Brooklyn, NY
    Are you measuring the V drop accross the diode with the power on?
    If so, can you measure with the 'diode' setting on your meter with the power off?

    I only ask to do these tedious things because it looks like you are in Beijing, and return for refurbish will take time and money.
  • afliuafliu Beijing, China
    thanks for your location kind consideration, Biomurph.

    No worry about doing these "tedious" things, I am happy to do anything to isolate the problem.

    drop across D9 when power on: 0.01v
    drop across D9 when power off: 0.07v

    In order to confuse you, I paste the my measurement picture link below for the referece. After all, I am not the electrical engineer, but software engineer.

    http://pan.baidu.com/s/1pJ3lLLx

      

  • biomurphbiomurph Brooklyn, NY
    It does sound like the D9 diode is not good. 
    Can you try replacing it and see if that makes the fix?
  • afliuafliu Beijing, China
    Thanks Biomurph.

    Both of my two boards works well now after replaced the D9.
  • biomurphbiomurph Brooklyn, NY
    Fantastic!!
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