Monitoring Of Power Supply And Voltage - Pioneer DDJ-RB Service Manual

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5.3 MONITORING OF POWER SUPPLY AND VOLTAGE

A The MAIN uCOM (IC406) of this unit always monitors for power and voltage failure of the unit and will shut the unit
off immediately after an error is detected.
• Content to be monitored
Power supply voltage drop and power supply voltage rise generated by short-circuiting between any power-supply IC and
GND or excess current inside the MAIN Assy
Power to be monitored: V+5_A, V+5_HP, V+7, V-6, V+3R3_D
• MAIN UCOM Detection terminal and its terminal voltage
TP terminal near the R267 of MAIN Assy or IC406 (MAIN UCOM) pin 107 FAULT_DET.
Normal: Approximately 3.3 V
Abnormal: 0 V
B
• Timing of monitoring start
500 ms after the unit is turned ON
• Timing upon judgment as a failure
50 msec after an error is detected
• LED indication when an error is generated
All LEDs are unlit.
• Restoration method
If the unit shuts itself down because an error is detected, perform diagnosis, disconnect the USB cable,
wait for a while and then connect the USB cable on again.
• Diagnostic procedure
C
1 Disconnect the USB cable.
2 Remove R267 from the MAIN Assy. Note: This step will disable power monitoring.
3 Reconnect the USB cable.
4 As the unit is turned on in a normal way, check each voltage in this state.
Note: Because power will be forcibly supplied even if any voltage is abnormal, if abnormal voltage continues, the
defective point may produce heat, which may be dangerous. Therefore, during diagnosis, be sure to disconnect
the USB cable several seconds after they are connected so that forcible powering will not continue.
5 If the voltage of any power IC is abnormal, the circuit that uses that power or the power IC itself may be defective.
6 Repair the defective part then check that the power and voltage of the repaired part becomes normal.
7 Return R267 to its original position on the MAIN Assy.
Note: This step will enable power monitoring.
D
The circuit of this unit monitors for power and voltage failure from USB bus power and will shut the unit off
immediately after an error is detected.
• Content to be monitored
Power supply voltage failure from the USB bus power
Power to be monitored: V+VBUS
• MAIN UCOM Detection terminal and its terminal voltage
TP terminal of V_DET signal of MAIN Assy or IC406 (MAIN UCOM) pin 108 V_DET.
Normal: HI (3.3 V)
Abnormal (V+VBUS 4.2 V or less ) : LOW (0 V)
E
• Timing of monitoring start
120 ms after the unit is turned ON
• Timing upon judgment as a failure
570 us after an error is detected
• LED indication when an error is generated
All LEDs are unlit.
• Restoration method
If the unit shuts itself down because an error is detected, perform diagnosis, disconnect the USB cable,
wait for a while and then connect the USB cable on again.
• Diagnostic procedure
F
1 Check the V+VBUS power, connect the USB cable.
2 If the voltage is abnormal, the circuit that uses that power or the power IC itself may be defective.
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