Protection Circuit - Pioneer XV-EV61 Service Manual

1

7.1.7 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 SERVICE port (IC5501 pin69)to "+5V", connect AC power cord.)
There are three types of operations for the protection circuit, which are indicated on the LCD display when Service Test mode is entered:
POW WNG: The unit was shut down because of an abnormality in the AMP system. (The PROTECT line operates at the MID level.)
POW ERR: The unit was shut down because of a failure in the AMP system. (The PROTECT line operates at the LO level.)
DVD ERR: 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:
POW ERR:
• The Speaker terminal became overloaded because of short-circuit. (See 1.)
• 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.)
C
• 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 ERR:
• An error was generated in the main power supply inside the DVDM. (See 6.)
Protection circuit that activates against a POW ERR error
1 When the Speaker terminal becomes overloaded
N
R3601 R3607
1.8k 0
A
D
B
Front L ch
Q3601
R3603
33k
D3601
GND FL
D3603
DAP202K
R3668
22k
In Normal mode, the speaker (6 ohms) is connected between the
E
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.
→ After power off, unit recovers. (no reed to unit for 60
seconds)
F
130
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.
SP-TERMINAL
K
EVOL Assy
Assy
VD+5
R108
27k
R3669
+5V
22k
to
XPROTECT
R3639
27k
Q3640
C
Q3639
B
+
C3633
E
10/50
2
3
(Short W138 and W139)
Conditions
XV-EV61
3
4
FL display in Service Test mode
POW ERR
DVD ERR
DVD ERR
4