Changhong Electric PT4216, Service Manual, Page: 25 / 62

25
mode
”
.At the moment
，
examines DVI signal ceaselessly
，
so it can be awaken automatically in DVI mode. It is said that
when DVI signal inputs, it can work normally from standby state
4、
Power supply system
：
Power board has seven ways voltage output all together. They are
34V
，
12V
，
12VAU
，
A6V
，
D6V
，
D3.3V and
5V. 34V regulated by IC upc574 is provided to tuner for tuning voltage. 12VAU is provided to audio power amplifier.
A6V
、
D6V is changed 5V by LDO(example TA4805F),used by different circuit network. D3.3V is changed 2.5V and
1.8V by LDO(example LM1117,LM1084 etc.),used by different IC. 5V power supply is used by MCU
（
PIC16F505
）
,infrared receiver and k board assembly etc. when standby.
When standby, except above 5V supply, other powers are all off.
4.1 Main power form and power branch
：
4.1.1
、
5V-ST power branch
X P 9 1 5
5 t h p i n
5 V - S T
U 9 0 0
L M 1 1 1 7 - 3 . 3
X P 9 1 0
1 t h , 3 t h
p i n
K b o a r d
a s s e m b l y
K b o a r d c o n n e c t i o n
R e m o t e c o n t r o l
b o a r d a s s e m b l y
J 1 7 1 6 t h ? 7 t h p i n
U 9 0 2 P C F 8 5 6 3
8 t h p i n
U 9 0 1 P I C 1 6 F 5 0 5
1 t h p i n
3 . 3 V P U L L
3 . 3 V P U L L
3
3 . 3 V P U L L
4.1.2
、
D6V power branch
X P 9 0 0
1 1 th p in
D 6 V
U 9 1 3 、 U 9 2 3
T A 4 8 0 5 F
U 0 C 3 S C L , U O C 3 S D A ,
U O C S W 1 , U O C 3 S W 2 ,
S A W S W p o rt p o w er
su p p lied b y p u ll-u p resisto r
U P 7
L M 1 1 1 7 -1 .8
U P 7
L M 1 1 1 7 -1 .8
U 2 0 1 U 0 C 3
1 5 th , 6 9 th p in
U 2 0 1 U O C 3
3 6 th p in
V 1 _ 8 A N A
U 2 0 1 U O C 3
3 th , 1 1 8 th , 1 2 4 th
p in
V 1 _ 8 V 1
+ 5 V B
U 9 0 3
L M 1 1 1 7 -2 .5
U 6 0 0 M T 4 6 V 2 M 3 2 L G -4
2 th , 8 th , 1 4 th , 2 2 th , 5 9 th , 6 7 th , 7 3 th ,
7 9 th , 8 6 th , 9 5 th , 1 5 th , 3 5 th , 6 5 th ,
9 6 th , 5 8 th p in
＋
2 .5 V _ D D R
V C C 5 A
V C C 5 A
U P 1
L M 1 1 1 7 -3 .3
V _ 3 .3 A U 2 0 1 U O C 3
4 th , 7 th , 8 0 th ,
9 4 th , 1 1 0 th p in