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LM358: LM358P

user6350528
Expert 1500 points
Part Number: LM358
Other Parts Discussed in Thread: TL031

Tool/software:

During the FCT test, it was found that the alarm light did not go off, and it returned to normal after replacing it with another batch. Please help to see what the reason is, thank you

  • 0
    Guru 311380 points

    There is no alarm light in the schematic.

    If replacing the chip fixed it, then it sounds as if the chip got damaged, probably due to overvoltage.

  • 0
    TI__Guru 70341 points

    Hi user6350528,

    I agree with Clemens. TP4 and TP7 are likely responsible to drive the LEDs. The voltage amplitudes at TP7 and TP4 depend on the potential resistor setting. The output of the circuit gets readily saturated in both TL031 and LM358P. 

    Since LM358P is in DIP package (seems to be placed on a socket), replace LM358P on the "bad" board, you should know which op amp is likely damaged. It is also that nothing is damaged due to the potential voltage settings. In other words, turn the pot slightly one way to turn on one LED; opposite direction will turn on the other LED due to the integrator. 

    If you have other questions, please let me know. 

    Best,

    Raymond