Hitachi 51UWX20B Service Manual page 133

RH32 allows ABL fluctuations to
manipulate the Trigger Point of Shut
Down as screen brightness varies. ABL
is inverse proportionate to brightness.
This prevents false triggering.
PROTECT _DEF
See Low Voltage Shut Down
Circuit Diagram for continuation.
Vertical Output Circuit
10
R629 0.68 Ohm
Q604
R630
C610
Excessive Vertical
Current Det.
If the Vertical Output IC has a problem,
R629 will sense the current rise. The
voltage drop will be reflected at the base
of Q604 turning it on and producing a
Shut Down high.
Too High Det.
ABL
PPD3
6
28V
R631
D608 R632
DK90
Flyback
TH01
ABL Voltage
5
3
5OP
1
RH32
RH25
DH15
RH24
Excessive Hi
Any fluctuations in High Voltage will
Voltage Det.
also be reflected by the 50P output P/P.
By monitoring the 50P (50 Pulse) rises
in High Voltage will be sensed. If High
Voltage climbs too high, DH15 will fire
and trigger a shut down event.
D702 monitors the Side Pin
Drive IC. If the voltage at
pin 7 rises too high, D702
will fire generating a Shut
Down high.
D703
D702
HZS7C3
Convergence Out Circuit
RK97
-5V
RK98
+5V
A loss of the Negative 5V will cause the
positive 5V to be felt on the anode of
DK90 which forward biases the diode
and delivers a Shut Down high.
133
High Voltage
Sensing Circuit
RH23
DH13
RH26
7
LH06
DH14
Stops H. Drive
29.01V
CH17
Side Pincushion Circuit
7
R717
Side Pin Failure
High Det.
-5V Loss
Detection
DP23/23G/24
Hi Volt
Drive
OVP