Voltage Monitoring Circuit - Pioneer DJM-2000 Service Manual

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5.3 VOLTAGE MONITORING CIRCUIT

A
Voltage Monitoring
This unit monitors the voltages of the main power-supply units, using VDET signals.
The VDET signal level is middle (+1.08 V to +1.32 V) during normal operations. When the level falls outside the middle level,
as shown in the table below, microcomputer A (IC1105) is notified of an error.
Product behavior when an error is generated
Upon reception of a VDET signal that informs of power failure, microcomputer A sets the Pcon signal to Low and stops the
switching-system output from SW power. Microcomputer A instructs that the STANDBY LED signal be sent so that the
UTILITY button will flash to notify the user of a power failure.
Flashing intervals: 250 ms (lit for 125 ms/unlit for 125 ms)
As the switching-system output is stopped, the indications other than the UTILITY button are unlit and all the switches and
VRs are disabled.
B
Diagnostic procedure
If any voltage is abnormal, that error will be detected by the voltage monitoring program after it is started after a usual start-
up of the unit. Then the SW power output will be stopped. For this reason, power will be supplied for about 10 sec after start-
up. Identify which power-supply IC is defective by turning the unit OFF then back ON while monitoring each voltage on an
oscilloscope. Check the value of each voltage immediately before stopping power supply.
Note: Each time before turning the unit ON, make sure that each power-supply IC is not short-circuited to GND.
Circuit diagram of the voltage monitoring section
V + 1 2 D V + 5 D
R 1 0 3 7
1 0 k
R 1 0 3 6
1 k
G N D D G N D D
C
G N D D
I
6/6
MAIN ASSY
J
1/2
HAMP ASSY
D
Q 5 6 1 5
2 S A 1 5 7 6 A ( R S )
V+15A
V-15A V+5A V-15A
Table: List of voltage values for power monitoring and statuses of the voltage comparator transistors
State Power
E
In normal operation
V+12D
V+5D
V+3R3D
When an error
is generated V+1R2D
V+15A
V-15A
F
V+5A
26
1
2
V + 5 D V + 3 R 3 D V + 3 R 3 D V + 1 2 D
R 1 0 4 1
1 0 k
R 1 0 4 0
1 k
G N D D
R 1 0 4 4
1 0 k
G N D D G N D D
V A D E T
R 5 7 7 8
1 0 k
R 5 7 8 2
2 S A 1 5 7 6 A ( R S )
Q 5 6 1 4
1 k
V+5A
Voltage
Q1002 Q1003 Q1004
OFF OFF OFF
< 10.2V ON OFF OFF
> 13.2V OFF OFF ON
< 4.2V OFF ON OFF
> 5.77V ON OFF OFF
< 2.8V OFF OFF ON
> 3.8V OFF ON OFF
< 1.08V OFF OFF OFF
> 1.32V OFF OFF OFF
< 14.1V OFF OFF OFF
> 15.9V OFF OFF OFF
< -16.8V OFF OFF OFF
> -13.2V OFF OFF OFF
< 4.4V OFF OFF OFF
> 5.6V OFF OFF OFF
2
3
Low value Hi value
V+1R2D 1.08V 1.32V
3.8V
V+3R3D 2.8V
5.77V
V+5D 4.2V
13.2V
V+12D 10.2V
V + 1 2 D
V + 1 R 2 D
R T 1 P 2 4 1 M - 1 1
Q 1 0 0 5
Q 1 0 0 6
R T 1 N 2 4 1 M
G N D D
G N D D
3E
Q 1 0 0 1
R T 1 N 2 4 1 M
G N D D G N D D G N D D
Low Value Hi Value
14.1V
V+15A
V+12D
V-15A 13.2V -16.8V
V+5A
4.4V
R 5 7 9 1
V A D E T
0
GNDA
GNDD
Statuses of voltage comparator transistors
Q1006 Q1005 Q5614 Q5615
OFF OFF OFF OFF
ON ON OFF OFF
ON ON OFF OFF
ON ON OFF OFF
ON ON OFF OFF
ON ON OFF OFF
ON ON OFF OFF
OFF OFF OFF OFF
OFF OFF OFF OFF
OFF OFF ON OFF
OFF OFF OFF ON
OFF OFF ON OFF
OFF OFF OFF ON
OFF OFF OFF ON
OFF OFF ON OFF
DJM-2000
3
4
I 1/6
to microcomputer A
1:6G
V D E T
NORMAL
1.08V 1.32V
ABNORMAL
<1.08V
>1.32V
15.9V
5.6V
VDET
Voltage
Q5616 Q5617 Q1001
OFF OFF OFF Mid
OFF OFF OFF
OFF OFF OFF
OFF OFF OFF
OFF OFF OFF
OFF OFF OFF
OFF OFF OFF
OFF OFF OFF < 1.08V
OFF OFF OFF > 1.32V
ON ON ON Low
ON ON ON Low
ON ON ON Low
ON ON ON Low
ON ON ON Low
ON ON ON Low
4
Hi
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