Voltage regulator not working

darkrubiksdarkrubiks Brasil
in Cyton
Hi, 

the 3.3V voltage regulator 

(MCP1754T-3302E/OT) on my cyton board is not working anymore, if I buy the component itself, can I replace the faulty one? 

Comments

  • wjcroftwjcroft Mount Shasta, CA
    Dark, hi.

    When did you purchase the board? Do you have any idea what happened to cause it to fail? Your voltmeter shows the battery voltage reaching the regulator, but no output? Here is a related thread on a protection diode failure,


    You can email to contact at openbci.com and ask the lab for advise. If indeed the regulator has blown, it should be possible to replace it. But I don't recall seeing any past users mentioning this.

    Regards,

    William

  • darkrubiksdarkrubiks Brasil
    Hey wjcroft,

    I think the board was bought 2 years ago, it's the version 3 of Cyton board. I reached out to my conclusion because the U5 component( the 3.3V voltage regulator) was getting very hot, and when i measured the input voltage i got something about 2.8V and the output was at 0V.

    I followed the instructions mentioned in the thread you sent me, here is what I found:

    The battery voltage was at 4.1V

    DVDD = 0V
    AVDD = 0V
    AVSS = 0V

    I checked the protection diode(D9) and got 0V in the diode test of the multimeter, so I tested the same diode but this time powered on and got two different results for PC mode and BLE mode, in PC the voltage after the diode was 2.8V and in BLE 3.8V, and the 2 voltages appeared at the input of the 3.3V voltage regulator, but got 0V as output.

    Thanks.


  • wjcroftwjcroft Mount Shasta, CA
    Hmm, your battery is 4.1 (with no load?), I assume a lithium cell? Voltage drop across the protection diode should only be about .7 volts. So 4.1 - .7 = 3.4. But unclear how you measured battery. Since the voltage regulator does indeed appear to be sick if overheating, that means it is drawing lots of current. So your voltage input measurements at the Vreg are going to be distorted.

    There is no difference in the power circuitry between the power switch PC and BLE positions. That only controls a logic input signal to the processor.

    Sounds like you could replace the Vreg. Be careful. Do you have the proper solder sucker and fine tip iron for SMT work?

    Regards,
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