Power Supply; Control Board - LG 42PG20 Training Manual

Y-SUS DRIVE WAVEFORM
RAMP 150V To Peak
Y-SUS TP
SUS-DN 110uS
P1
Ch1 100V 100us 540Vp/p
62V~57V (AC) rms (Dark to White)
P2
VR602 Y-SUSTAIN
VR601
TP Ramp
FS202
Set-dn
(VS)
125V 4A
P204
P3
P4
-VY TP
R210
P5
P211
VSC
P6
VR501
VZB TP
-VY
R946
VSC TP
VR502
5V Fuse
R211
VZB
VR905
FL1 P202
P7
+
P202
-
To Check 5V to Pin Label STBY Run
C18
the Y Drive, 1 Gnd Gnd Gnd
P8
2 Gnd Gnd Gnd
measure
3 15V 0V 15.8V
across capacitor
4 ER2 0V 61.5V
C18.
5 ER2 0V 61.5V
The voltage is
6 Va 0V 64.9V
supplied thru
7 Gnd Gnd Gnd
FL1. 8 Gnd Gnd Gnd
9 15V 0V 15.8V
10 ER1 0V 61.5V
11 ER1 0V 61.5V
12 Va 0V *64.9V
*Varible according to Label
P201 P202 P203
42PG20 CIRCUIT INTERCONNECT DIAGRAM
4mS
Pin STBY Run
1
2
3
4
5
6
P201
7
Pin Label STBY Run
8
1 Vs 0V *194V
2 Vs 0V *194V 9
3 nc nc nc
10
4 Gnd 0V 0V
5 Gnd 0V 0V
6 Va 0V *65V
7 Va 0V *65V
8 Gnd 0V 0V
9 M5V 0V 5V
A/C IN
10 M5V 0V 5V
CN101
*Variable according to Label
P201
SMPS Test – Unplug P813 If all supplies do not run when A/C is
reapplied, disconnect P812 to isolate the excessive load. This supply
will operate with no external load.
P801
FS201 (5V)
125V 1.5A
IC121
Pin 1 (5V)
Pin 2 (3.3V)
Pin 3 (0V)
P101
CONTROL
FS701 (VA)
FL111 FL112
125V 10A
5V Fuses
Fusable
P160
Link
Pin 1 (5V)
Pin 2 (3.3V)
Pin 3 (0V)
Va and 16V
P232
LEFT X DRIVE
P204
P205
P812 P813
Pin STBY Run No Load P812
0V *195V 1, 2 0V 16.5V 16.5V
0V *195V 3, 4 Gnd Gnd Gnd
0V 0V 5, 6 NC NC NC
n/c n/c 7, 8 Gnd Gnd Gnd
0V 0V 9, 10 5V 5V 5V
VS Adj
0V *65V 11, 12 5V 5V 5V
R951
VA Adj
0V *65V 13, 14 Gnd Gnd Gnd
0V 0V 15, 16 Gnd Gnd Gnd
0V 5V 17 .15V 5V 5V
0V 5V 18 5V 5V 5V
SMPS PCB
19 0V 3.73V 0V

POWER SUPPLY

20 0V 3.2V 0V
21 0V 3.24V 0V
22 0V 0V 5V
P813
No
Unplug all connectors. Jump 5V from SMPS
Connection
(P813 pins 9~12) to pin 1 of IC121. Observe
Temp LEDs. If they light, most likely Control
P121
TEMP LEDS
P164 P131
PWB is OK. 1
X101
50 Meg
ROM Disconnect P201 from the Y SUS Board and
Updates
connect a Jumper from Pin 10 of P812 (M5V) to
With the unit on. If none of
Pin 10 P201 (5V). The 5V will be routed to the
D15, 16, 17 are illuminated.
Control Board via FS201, Ribbon Cable P101 on
Check supplies to the PCB.
the Y SUS Board and FL111 and FL112 on the
PCB
If they are present replace
Control Board for Control Board operation
the Control PCB
verification.
Auto Gen
Short across the two
points labeled Auto Gen
to generate a test
P161 P162
pattern.
If the complaint is no video and
shorting the points (AutoGen) causes
video to appear suspect the Digital PCB.
P211 P311 P331
P206
P301
See next page for
waveforms
P302
Remove all input signals
Pin State Ref#
from the unit so the
Menu Off
menu will be the only 11
Menu On
video to be found on the
Menu Off
LVDS cable.
12
Menu On
NOTE: White noise from
Menu Off
the tuner may cause
13
Menu On
these signals to vary.
Menu Off
These were taken with
14
Menu On
the unit set to
Menu Off
component with no input
15
R901
Menu On
signal.
Menu Off
16
Menu On
Menu Off
19
Menu On
Menu Off
20
Menu On
Menu Off
21
Menu On
Menu Off
22
Menu On
DIGITAL PCB: Remove all input signals from the
unit so the menu will be the only video to be found
st
check FL111 and FL112.
on the LVDS cable.
NOTE: White noise from the tuner may cause
these signals to vary. These were taken with the
unit set to component with no input signal.
LVDS
P701
IC705
P302
LD703 Lights Red in
MAIN
Stby. 5VSBY from
SMPS OK. Set on,
Lights Red 5V General
Q706
LD703
OK. Appears Amber
IC708
P303
To keys and IR
IC501
To Speakers
JK501
RIGHT X DRIVE
P304
P302 P303
Z-SUS
VZ Bias
Z-SUS TP
10
11
08
09
Ch1 50.0V 100us 220Vp/p
12
13
52V (AC) rms
06
07
14
P2
15
04
05
16
17
02
03
18
19
00
01
Z-SUS TP
R1 Bottom Leg
P1
P3
**LD400 lit during initialization. Tuner lock OK turns LED off.
IC702 IC702
IC709
5) .29V 1) 3.29V
Reset
4) 5V 2) 1.26V
IC709 IC101
3) 0V 3) 0V
2) 0V
**LD400
Pin 16
1) 0V
IC501
1) 3.3V
X400
Pin 1 IC705
2) 1.8V
PCB IC100
1) 5V
TUNER 3) 0V
Micro
25 Meg
2) 3.29V
3) 0V
X100 Run Only
IC805
12 Meg
IC706
TUNER 1) 5V
1) 5V
2) 3.3V
Pin 16 Video
1.5V SBY
2) 2.6V
3) 0V
Pin 14 SIF
3) 1.37V
IC708 IC101
Pin 1
Grayed Out ICs are
1) 5V 1) 5V
located on Back
IC805 2) 3.31V 2) 0V
3) 0V 3) 5V
P306
P305