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Home ‣ Digital Electronics ‣ MSI Logic Circuits See What Others Are Saying!
  • Question

  • There appears to be a problem with a 7-segment display on a DMM sometimes skipping certain numbers. How would you test the display?


  • Options
  • A. Remove the display unit and check each segment diode with an ohmmeter. Replace the defective segments.
  • B. Apply 5 V directly to each segment of the display and check for individual segment operation. Replace any segment that has voltage applied but is not lit.
  • C. Tie all of the segments together and connect to Vcc; the number 8 should appear on the display. Now check the display supply voltage to determine if the display is receiving the correct voltage.
  • D. Connect the DMM to a variable supply and very slowly increase the voltage, while observing for missing digits. Then check the segment voltage to determine whether the display or the display driver is bad.

  • Correct Answer
  • Connect the DMM to a variable supply and very slowly increase the voltage, while observing for missing digits. Then check the segment voltage to determine whether the display or the display driver is bad. 

    • More questions

    • 1. The first microprocessor had a(n)________.

    • Options
    • A. 1-bit data bus
    • B. 2-bit data bus
    • C. 4-bit data bus
    • D. 8-bit data bus
      • Discuss
    • 2. If a 3-input OR gate has eight input possibilities, how many of those possibilities will result in a HIGH output?

    • Options
    • A. 1
    • B. 2
    • C. 7
    • D. 8
      • Discuss
    • 3. The select inputs to a multiplexer may also be called address lines.

    • Options
    • A. True
    • B. False
      • Discuss
    • 4. How many 2-input NOR gates does it take to produce a 2-input NAND gate?

    • Options
    • A. 1
    • B. 2
    • C. 3
    • D. 4
      • Discuss
    • 5. The 7476 and 74LS76 are both dual flip-flops.

    • Options
    • A. True
    • B. False
      • Discuss
    • 6. How many different states does a 3-bit asynchronous counter have?

    • Options
    • A. 2
    • B. 4
    • C. 8
    • D. 16
      • Discuss
    • 7. The invalid range for an input to TTL logic is from ________.

    • Options
    • A. 0 to 0.8 V
    • B. 1.2 to 1.6 V
    • C. 0.8 to 2.0 V
    • D. 2.0 to 5.0 V
      • Discuss
    • 8. A typical fan-out for most TTL is 9.

    • Options
    • A. True
    • B. False
      • Discuss
    • 9. The outputs of the 74138 octal decoder are enabled when the enable inputs are
      .

    • Options
    • A. True
    • B. False
      • Discuss
    • 10. Convert the following hexadecimal number to decimal.
      B516

    • Options
    • A. 212
    • B. 197
    • C. 165
    • D. 181
      • Discuss

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