Pioneer SC-27 Service Manual page 51

5
DIGITAL MAIN Power Supply Failure Detection
Item Purpose
DIGITAL Detect abnormal
MAIN voltage in the
power Digital Power
supply Supply circuit
failure
detection
E
DIGITAL MAIN ASSY
V+5R6_U
V+13_UN
R1999
1SS352
4.7k
IC1900
D1998
DAP202U
PWRGD
IC1930
PGOOD
(*1) Conditions when XVDDERR becomes "L"
1. Q1997 turns ON : When V+6DDD becomes higher than the setting value, Q1997 becomes ON.
2. Q1998 turns ON : When V+5_DDD becomes higher than the setting value, Q1998 becomes ON.
3. Q1999 turns ON : When V+13_UN becomes lower than 3.8V, Q1999 becomes ON.
When PWRGD of IC1900 becomes low (V+5HD becomes lower than the setting value), Q1999 becomes ON.
When PGOOD of IC1930 becomes low (V+1R8_HHH or V+3R3_HHH drift from the setting value), Q1999 becomes
ON.
When V+6_DDD becomes lower than 3.8V, Q1999 becomes ON.
[How to Enter Release Mode]
During Standby mode, simultaneously press and hold the "↓" and "MULTI-ZONE ON/OFF" keys
for 5 seconds.
5
6
Detection Method
Detect when XVDDERR
port becomes "L" (*1).
(IC8001 70pin)
Q1999
RN4903
D1997
Q1999
RN4903
GNDD
V+6_DDD
6
7
Status of Equipment
Shuts down Blinks Center Blue LED
V+5_DDD
D1995
UDZS6R8(B)
SC-27
7
8
Warning Indication Remarks
V+13_UN
8
A
B
C
D
E
F
51