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Overvoltage Port F
Allen D. Sep 28, 2016 at 02:35 PM (14:35 hours)
Staff: Johnny N.

  • Hello,

    During some testing, 6V was accidentally applied to port F on the PE Micro Multilink part number USB-ML-UNIVERSAL. When plugged into the USB port, the blue LED comes on and the orange one does as well when target power is applied. However when programming is executed it fails to enter background mode. I have already tried removing zener diode T2 and T3 but have had no luck getting it working. Any suggestions? Thank you.


  • Hi Allen,

    Some additional ICs must have also been damaged by the over-voltage. Are there any other components that show signs of electrical damage or get hot when you apply 5V to the Vdd pin?


  • The main MCU gets warm a bit, but nothing else gets very hot. Is there anything I can do to salvage it? I would think that if the blue light comes on and the software can detect the flash version number, that it could still be salvageable. Please advise, thank you.

    • Hi Allen,

      I can give you a list of components you can try to replace. Do you have a USB-ML-UNIVERSAL Rev C? If the main MCU is damaged in anyway, then you will have to replace the entire unit. The cost of the replacement is $100.

      PEmicro Engineering Support

      • Thanks John, it is rev B. The yellow light does come on when the target gets power so it appears that the main MCU is still working.

        • You can try replacing the following components.

          Protection Diodes:
          T2,T3 Fairchild 1N752A_T50R; 1N5232B

          Output Buffers:
          U9, U10, U14 TI SN74LVC2G126DCTR

          U21    TI SN74LVC1G08DBVRE4   
          U22 TI SN74LVC2G08DCTR
          U24 TI SN74LVC1G66DBVRG4

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