As problem of title, I have received the problem report from quality assurance department.

I would like to inform about problem report detail.

  • Problem detail
    Product ; AJY126LALH ( R001173)
    Problem contents ;
    When commissioning, transmission error was occurred. Technician found PCB that is measuring short on the X1 and X2 terminals.
  • Analysis result
    <Analysis sample unit>

    Between each terminal resistor value(actual)

    (1) FGL could not find the conspicuous damage on the PCB.

    (2) Even if terminal setting is on or off, the result is short not only X1-X2 but also X1-G, and X2-G.

    (3) The correct condition of ground terminal ①②③ is homopolar(0Ω). but, ground line of G① became open.(O.L)

    (4) Based on these result, FGL checked L111(filter component for noise reduction),4 pin and coil was open.
    Another all pin was conduction. But, FGL could not find the error condition by X-ray photo.


    (5) Confirmation of L111 by X-ray


    As to between 1,2,3,5,6 pin and coil, there may be problem at bobbin of coil. Therefore, FGL request analysis to L111’s manufactured company.

    <Analysis result from L111’s manufactured company >
    4 Pin of L111 was melting(open). As to another wire covering, some parts was melting. Then copper wire was exposed.
    As the result, among each coil was short.
    Before this parts will ship from manufactured company, manufacture company is doing the electric testing at all parts.
    Therefore, they don’t think that this parts had been shipped at this condition.
    And, they don’t think too that it become this condition at manufactured process.

    So, Manufactured company guess that this problem had occurred after shipped from manufactured company due to over current (100mA or more) was flowing to this parts.

    • < Traceability of this product ; AJY126LALH ( R001173)>
      At FGCA factory also, testing had been carried out. For check of PCB, PCB was connected to PC using X1-X2 terminal.
      FGL checked test record of this product. But test was completed correctly.
      Therefore, the problem was nothing at shipping from FGCA factory.

    • Test record at FGCA factory of AJY126LALH ( R001173)


      check log when testing(not all)

    • Speculation of this result’s cause
      Like above result, this problem was nothing when product had been shipped from FGCA factory.
      FGL thinks this problem was occurred after shipping.

      Transmission level of Lon communication is max 1,500mVp. so, the maximum current which will flow to X1-X2 is 30mA level.
      So, there is the margin compared with parts specification.
      As to the product proof stress correspond external factor, it meet the FGL design criteria.
      So, from the perspective of design also, problem is nothing.

      At the moment, FGL cannot think possibility that this problem occurs biasedly is very low.
      Therefore, FGL watches to market.