Impedance check - All electrodes appear to be floating

AmiyaAmiya Singapore
edited February 2017 in Ganglion
I tried a proper setup with my newly received board (two EEG and two EOG channels). Unfortunately it appears as if the electrodes are floating and impedance check just does not work wit all impedance being shown as 0K. I am unsure what is happening. Is my board damaged?

Comments

  • wjcroftwjcroft Mount Shasta, CA
    What happens if you follow the exact steps in the tutorial?

  • AmiyaAmiya Singapore
    @wjcroft It still does not work. Impedance appears to be 0 and I get random voltages as high as 700 uV even when nothing is connected to the electrodes. Touching the electrodes has no effect on this signal.
    I am wondering if the unit is faulty. 
  • wjcroftwjcroft Mount Shasta, CA
    Forget about impedance for the moment. Do you see the ECG and EMG as the tutorial shows?

    Always check for bad cables or connectors. You can use a DVM digital voltmeter, on the ohms scale. Electrodes should be very low close to zero ohms. Swap your cables around in case you have a faulty one or ones.

  • wjcroftwjcroft Mount Shasta, CA
    Be sure to set your switches on the Ganglion board as shown in the tutorial. If you select Referential vs. Differential, nothing will work as expected.
  • AmiyaAmiya Singapore
    No I do not see any ECG or EMG signal...I get the same signal irrespective of if the electrodes are connected or not. Yes I made sure that switches are set in referential mode. 
    Thanks
  • wjcroftwjcroft Mount Shasta, CA
    The switches should be in differential mode for the EMG / ECG.
  • biomurphbiomurph Brooklyn, NY
    @amiya
    have you resolved this issue? for doing ECG and EMG, the on-board dip-switches should be in the UP position. With the switch lever alighned with the white markings on the switch.
  • AmiyaAmiya Singapore
    edited March 2017
    Not really, the board still does not appear to be working. I also noticed that the impedance appears to be stuck at 0K and doesn't change even if nothing is connected to the pins or if the pins are shorted with ground or ref! Random signals appear on all channel in the 1mV range.  I am completely clueless about what could be the problem. 
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  • AmiyaAmiya Singapore
    I realized even the accelerometer appears to be stuck 


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