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1
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.
A
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.) (Refer to "7.1.6 SERVICE TEST MODE")
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
Voltage
HI level
B
PROTECT
MID level
LO level
HI level
VDET
MID level
LO level
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.)
C
• 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.)
Protection circuit that activates against a PRTCT WNG error
1 When the Speaker terminal becomes overloaded
R3601
R3607
D
1.8k
0.1
A
POWER Assy
B
Front L ch
Q3601
R3603
33k
D3601
GND FL
D3603
DAP202K
E
In Normal mode, the speaker (6 ohms) is connected between the
FL and GND FL points. Because the voltage at Point A is higher
than that at Point B, Q3601 does not operate.
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.
F
116
1
2
>3.55V
Normal
1.8V - 3.5V
The unit is shut down because of an abnormality.
<1.8V
The unit is shut down because of a failure.
>4.25V
The unit is shut down because of a failure.
3.3V
Normal
<2.5V
The unit is shut down because of an abnormality.
J
I
AMP Assy
VD+5
R108
27k
+5V
to
XPROTECT
R3639
27k
Q3640
C
Q3639
B
+
C3633
E
10/50
2
3
Conditions
POWER Assy
VD+5
R90
27k
to
SYSPOW
Q83
RT1P241M
XV-EV500
3
4
FL display in Service Test mode
PRTCT WNG
PRTCT ERR
DVD PRTECT
DVD PRTECT
RY81
XSR3008
Q81
2SD1858X(QR)
R83
D87
18
DAN217
R84
18
4
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