XV-DV740
114
1
2
4
1
2
3
4
C
D
F
A
B
E
7.3.2 PROTECTION CIRCUIT
If the TIMER LED on the front panel flashes, check the protection circuit.
Note: If the protection circuit activates, the unit will not recover for 60 seconds even if the AC power cord is disconnected then reconnected.
If you activate Service Test mode, the protection circuit becomes invalid, which makes diagnosis easy. (To activate Service Test mode,
while connecting STEST port (IC5501 Pin43) to "+5V", connect AC power cord.)
There are three types of operations for the protection circuit, which are indicated on the FL display when Service Test mode is entered:
PRTCT WNG: The unit was shut down because of an abnormality in the AMP system. (The PROTECT line operates at the MID level.)
PRTCT ERR: The unit was shut down because of a failure in the AMP system. (The PROTECT line operates at the LO level.)
DVD PRTECT: The unit was shut down because of a failure in the DVD system. (The VDET line operates at the HI or LO level.)
Conditions for the protect circuit operations
Protection circuit that activates against a PRTCT WNG error
Voltage
Conditions
FL display in Service Test mode
PROTECT
HI level
>3.55V
Normal
MID level
1.8V - 3.5V
The unit is shut down because of an abnormality.
PRTCT WNG
LO level
<1.8V
The unit is shut down because of a failure.
PRTCT ERR
VDET
HI level
>4.25V
The unit is shut down because of a failure.
DVD PRTECT
MID level
3.3V
Normal
LO level
<2.5V
The unit is shut down because of an abnormality.
DVD PRTECT
The possible failures for each error message are as follows:
PRTCT WNG:
• The Speaker terminal became overloaded because of short-circuit. (See
1
.)
PRTCT ERR:
• The main power supply became LO level because of short-circuit or disconnection of connectors. (See
2
.)
• Disconnection of the FAN connector or interruption of rotation of the fan (See
3
.)
• DC was generated at the output because of a failure in the AMP system, etc. (See
4
.)
• Abnormal temperature was detected by the thermistor. (See
5
.)
DVD PRTECT:
• An error was generated in the main power supply inside the DVDM. (See
6
.)
1
When the Speaker terminal becomes overloaded
Q3601
E
C
D3601
R3607
0.1
R5559
270k
R108
27k
Front L ch
to
XPROTECT
GND FL
R3601
1.8k
R3603
33k
B
A
VD+5
POWER Assy
J
6CH AMP Assy
D
TRADE2
Assy
H
A
is higher
If the resistance between the FL and GND FL points becomes
1.83 ohms or less, Q3601 begins to operate, Q3639 is turned on,
Q3640 (E, C, and B)is turned on, and the level of XPROTECT
becomes MID.
→
The microcomputer detects the XPROTECT level and
shuts the power to the unit off.
www. xiaoyu163. com
QQ 376315150
9
9
2
8
9
4
2
9
8
TEL 13942296513
9
9
2
8
9
4
2
9
8
0
5
1
5
1
3
6
7
3
Q
Q
TEL 13942296513 QQ 376315150 892498299
TEL 13942296513 QQ 376315150 892498299
