About Power Supply Monitoring; About The Protectors - Pioneer CDJ-850 Service Manual

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5.5 ABOUT POWER SUPPLY MONITORING

The Panel CPU of this unit always monitors for power failure of the unit while power is on and will shut the unit off
immediately after an error is detected and notify of the error by LED indications.
A
• Content to be monitored
Any power failure generated inside an Assy or Power Supply Assy, such as voltage drop and voltage rise
Power to be monitored: V+7R6_M, V+12, V+5R6, V+1R2, V+1R25, V+3R3_S, V-10_A, V+3R3_SW, V+6R6_FL, V+38
• Microcomputer Detection terminal and its terminal voltage
44-pin VDET terminal of IC1007 (PANEL CPU)
Normal: 3.3 V
During power failure: 0 V
• Timing of monitoring start
0.1 sec after the unit is turned ON
B
• Timing upon judgment as a failure
0.5 sec after an error is detected
• LED indication when an error is generated
If an error is generated, the STANDBY LED will flash after the unit shuts itself off.
• Restoration method
After the unit shuts itself off because of an error, after completing diagnosis, unplug the AC power cord and wait about
1 minute before turning the unit back on.
Error-detection status is retained for about 1 minute after the AC power cord is unplugged, during which time signals
C
from the POWER switch are not accepted and the unit cannot be turned on.
Diagnostic procedure
1 Unplug the AC power cord.
2 Remove R1123 from the DFLB Assy.
Note: This step will disable power supply monitoring.
3 Plug in the AC power cord.
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 unplug the
AC power cord several seconds after it is plugged in so that forcible powering will not continue.
D 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 detective part.
7 Return R1123 to its original position on the DFLB Assy.
Note: This step will enable power supply monitoring.

5.6 ABOUT THE PROTECTORS

E
This unit is provided with protectors (elements for protection against excess current) on the power lines to protect the unit's
parts and circuits from excess current and excess voltage. If any abnormal power short-circuiting is generated, a protector
will be activated to protect parts and circuits.
• Locations and functions of protectors
P2003 DEK1095-: Protection against excess current on the V+12_A and V+10_A lines
P2004 DEK1095-: Protection against excess current for V+12_EUP and against excess voltage for its subsequent circuits
Diagnostic procedure
1 Unplug the AC power cord.
2 Check for any error, such as short-circuiting or defective parts, in the circuits subsequent to the protector.
F
3 Repair the detective part.
4 Replace the protector.
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