Premier Service Center Certification: Advanced Amplifiers

31 Questions | Total Attempts: 50

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Premier Service Center Certification: Advanced Amplifiers - Quiz

Thank you for taking the time to participate in the QSC Premier Service Center Certification program. To become a QSC Premier Service Center, you must pass four tests built off the online training material courses. This certification program is intended to allow your Service Center become fully capable and knowledgeable in servicing QSC products professionally and reliably. This third test will cover the more advanced amplifeir technologies, like Class H and Class D. Good luck!


Questions and Answers
  • 1. 
    What specific type of Class H output circuitry do QSC amplifiers use? Mark all that apply.
    • A. 

      1-tier

    • B. 

      2-tier

    • C. 

      3-tier

    • D. 

      4-tier

  • 2. 
    Does QSC offer any power amplifiers with Class D output circuitry technology?
    • A. 

      Yes

    • B. 

      No

  • 3. 
    How many bipolar supply rails (count POS & NEG rails as 1) does a Class AB output circuitry use?
    • A. 

      1

    • B. 

      2

    • C. 

      3

    • D. 

      4

  • 4. 
    How many bipolar supply rails (count POS & NEG rails as 1) does a Class H output circuitry use?
    • A. 

      2 or more

    • B. 

      0

    • C. 

      1

    • D. 

      2 positive rails and 1 negative rail

  • 5. 
    What type of circuit is the step driver (the circuit that turns the MOSFET switch off and on) in a Class H amplifier?
    • A. 

      Comparator

    • B. 

      Resistor network

    • C. 

      H-Bridge

    • D. 

      Stair circuit

  • 6. 
    What is the primary purpose of the MOSFET in a Class H amplifier?
    • A. 

      To switch the output to a higher voltage rail.

    • B. 

      To flip the voltage of the rail from positive to negative.

    • C. 

      To allow for higher currents.

    • D. 

      To put moss on your fet.

  • 7. 
    What are some of the advantages of a Class H output circuitry? Mark all that apply.
    • A. 

      More efficient

    • B. 

      Reduced current consumption

    • C. 

      More components

    • D. 

      Easy to troubleshoot

  • 8. 
    How many pairs of step drivers (if you count POS & NEG as 1 pair) should a 2-tier Class H amplifier have?
    • A. 

      0

    • B. 

      1

    • C. 

      2

    • D. 

      3

  • 9. 
    What are some of the disadvantages of a Class H output circuitry? Mark all that apply.
    • A. 

      More components

    • B. 

      Increase in heat

    • C. 

      More current consumption

    • D. 

      Easy to troubleshoot

  • 10. 
    In a class H amplifier, the positive step driver circuitry differs from the negative step driver in which way?
    • A. 

      The positive step driver has a bootstrap power supply.

    • B. 

      The positive step driver has a comparator and the negative step driver does not.

    • C. 

      The positive step driver is in a good mood and the negative step driver is in a bad mood.

    • D. 

      Both step drivers are similar in every way, just changed for positive or negative voltage.

  • 11. 
      The comparator in a step driver of a Class H amplifier compares what voltages?
    • A. 

      Trigger and Reference

    • B. 

      CH1 output and CH2 output

    • C. 

      Output and Trigger

    • D. 

      Positive and negative references

  • 12. 
    What is QSC's most widely used switch-mode power supply platform called?
    • A. 

      PLC

    • B. 

      PFC

    • C. 

      PLX

    • D. 

      PLD

  • 13. 
    Which QSC amplifiers were developed with the PLC switch-mode power supply platform? Mark all that apply.
    • A. 

      PLX

    • B. 

      DCA

    • C. 

      Powerlight 2

    • D. 

      RMX

  • 14. 
    In the PLC platform's switching power supply circuit, how is input AC energy rectified to DC?
    • A. 

      Bridge rectifier

    • B. 

      Line filter

    • C. 

      DSP chip

    • D. 

      Torodial power transformer

  • 15. 
    In the AC Line Filter circuit of QSC's switch mode power supply, what type of fuse is used?
    • A. 

      Slow Blow (should not blow at short high current bursts)

    • B. 

      Fast blow (should blow immediately when drawing high current)

    • C. 

      500mA

    • D. 

      Any fuse rated for 25 A

  • 16. 
    In QSC's switch-mode PLC platform, at what frequency do the power supply IGBTs switch on and off?
    • A. 

      110 kHz

    • B. 

      10 Hz

    • C. 

      1 kHz

    • D. 

      1 MHz

  • 17. 
    What does the "I" in IGBT stand for?
    • A. 

      Insulated

    • B. 

      Inductive

    • C. 

      Current (amps)

    • D. 

      Inrush

  • 18. 
    In the schematic below of a power supply in the PLC platform, what is the purpose of IC U19?
    • A. 

      A controller IC that generates alternating signals for the gate driver IC.

    • B. 

      Maintains the voltage supply (16V and 5V) for the power supply.

    • C. 

      A gate driver IC that tells the IGBTs when to turn off and on.

    • D. 

      An IC that monitors that output circuitry and cut off to protect the power supply.

  • 19. 
    In the schematic below of a power supply in the PLC platform, what is the purpose of IC U18?
    • A. 

      A driver IC that provides valid gate drive pulse trains to the IGBTs.

    • B. 

      Maintains the voltage supply (16V and 5V) for the power supply.

    • C. 

      An IC that monitors that output circuitry and cut off to protect the power supply.

    • D. 

      An IC that makes giga-joules of energy, enough to power a Delorian.

  • 20. 
    What is the one of the purposes of the housekeeping supply circuit in the PLC platform?
    • A. 

      To provide the operating voltages for components within the power supply.

    • B. 

      To monitor all speaker output voltages.

    • C. 

      To provide timing for the gate driver circuit.

    • D. 

      To clean the power supply of any dirt.

  • 21. 
    In the PLC platform of amplifiers, what type of protect circuits exist in the power supply? Mark all that apply.
    • A. 

      AC Loss

    • B. 

      Undervoltage

    • C. 

      Overcurrent

    • D. 

      DC Fault

  • 22. 
    In the schematic below of a power supply in the PLC platform, what voltages does IC U13 pins 8 and 9 compare?
    • A. 

      The bridge rectifier input voltage to detect loss of AC

    • B. 

      The low voltage operating supplies.

    • C. 

      The secondary voltage supply rails.

    • D. 

      The voltage of the sync pin.

  • 23. 
    In the PLC platform of amplifiers, how does the power supply protect from overcurrent?
    • A. 

      By measuring the average current draw and reducing the load on the power supply.

    • B. 

      The housekeeping supply completley cuts off the main operating voltages, turning of the amplifier.

    • C. 

      By detecting the reduction of input AC near the line filter.

    • D. 

      By increasing the bias current to increase the secondary supply rails.

  • 24. 
    The switch-mode power supply in the PLX2-04 models and GX7 are simplified versions of what?
    • A. 

      The PLC platform of amplifiers.

    • B. 

      The MD module.

    • C. 

      The RMX Series amplifiers.

    • D. 

      Class H amplifiers.

  • 25. 
    In a Class D amplifier, what type of signal drives the switching transistors?
    • A. 

      Pulse Width Modulated (PWM)

    • B. 

      Trigger Referenced Comparator

    • C. 

      Low frequency square wave

    • D. 

      High frequency modulation (HFM)

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