LG 42PQ20 Training Manual page 119

Y-SUS DRIVE WAVEFORM
VR601
V Set-Up (Ramp)
Y-SUS TP
180V
A
+
- 5V
0V
B
V Set-Down
VR401
192us - +
5us
50VAC rms 100uS 528V P/P
Connect Scope between Waveform TP on Y-Drive and Gnd
Y-SUSTAIN
TP
VR601
SET-UP
FS201 (5V)
VSC
125V 4A
TP -
+
-
-VY TP
+
R201
VR501
R520
VSC
Fusable
VR502
Link
-VY
FS501 (17V)
FL1
125V 4A
+
FL1
P202
-
5V Fuse
Pin Label STBY Run
C18 Floating
1 Gnd Gnd Gnd
Ground
2 Gnd Gnd Gnd
3 Gnd Gnd Gnd
4
nc nc nc
5 *Va 0V 60V
6 0V
*Va 60V
7 *Va 0V 60V
To Check 5V to the Y Drive,
measure across capacitor C18. *Varible according to Panel Label
The voltage is supplied thru FL1.
LEFT X DRIVE
P201 P202
TCP
TCP
42PQ20 CIRCUIT INTERCONNECT DIAGRAM
P811
4mS
M5 (9,10)
Va (6,7)
Vs (1,2)
P201 Y-SUS and P811 SMPS
Pin Label STBY Run
1 Vs 0V *193V
2 Vs 0V
*193V
3 nc nc nc
4 Gnd 0V 0V
5 Gnd 0V 0V
6 Va 0V *60V
P201
7 Va 0V *60V
8 Gnd 0V 0V
FS202
9 M5V 0V 5V
(VS)
10 M5V 0V 5V
250V 4A
*Variable according to Panel Label
P206
Pin Label STBY Run
er com
1 0V *94.9V
2 er com 0V
*94.9V SMPS Test – Unplug P813 If all supplies do not run when A/C is
3 nc nc nc
reapplied, disconnect P811 to isolate the excessive load. This supply
4
Gnd Gnd Gnd
will operate with no external load. Use 2 (100W) light bulb test to
5 Gnd Gnd
Gnd
check under load.
P206
6
nc nc nc
Vs
7 0V *193V
Vs
8 0V *193V
VR401
SET-DN
FS203 (VA)
IC221
125V 10A
Pin 1 (4.95V)
Pin 2 (3.3V)
Fusable Links
Pin 3 (0V)
IC221
FL111 FL112
P101
15V and 5V
5V Fuses
Ribbon Cable
Pin 1 (4.95V)
Y-Drive Signals
Pin 2 (3.3V)
P111
Pin 3 (0V)
P202
With the unit on. If D201
does not blink on/off. Check
5V supply. If present replace
the Control PCB
Va
P211 / P311
Pin Label STBY Run
1 Gnd Gnd Gnd
2 Gnd Gnd Gnd
3
nc nc nc
4 *Va
0V 60V
5
*Va 0V 60V
Va
*Varible according to Panel Label
Note: 3.3V for X boards originates
P233 P211
from IC221 on the Control board
P204
P203 P205
TCP
TCP TCP
P813
Pin Label STBY Run No Load
1, 2 17V 0V 17V 17V
3, 4 Gnd Gnd Gnd Gnd
R502
5, 6 12V 0V 12V 12V
7, 8 Gnd Gnd Gnd Gnd
VA Adj
VS Adj
9, 10 9, 10 5V 5V 5V
11, 12 11, 12 5V 5V 5V
13, 14 13, 14 Gnd Gnd Gnd
R901
15, 16 15, 16 Gnd Gnd Gnd/nc
17 5V Det 0V 5V 5V
18 AC Det 4.6V 4.6V 5V
19 RL On 0V 3.73V 0V
SMPS PCB
20 Vs On 0V 3.2V 0V
POWER SUPPLY
21 M5 On 0V 3.26V 0V
22 Auto Gnd 0V 0V 5V
23 Stby5V 5V 5V 5V
24 Key On 0V 0V 5V
A/C IN
SC101
No
Unplug all connectors. Jump 5V from SMPS
LVDS
Connection
(P813 pins 9~12) to pin 1 of IC121. Observe
LED. If it blinks, most likely Control PWB is OK.
P121
P131
FL111 and FL112 should be checked.
X101
IC121
ROM
Disconnect P201 from the Y SUS Board and
Pin 1 (5V)
Updates
25 Meg Pin 2 (1.8V) connect a Jumper from Pin 10 of P811 (M5V) to
Pin 3 (0V)
Pin 10 P201 (5V). The 5V will be routed to the
IC231
Control Board via FS201, Ribbon Cable P101 on
CONTROL PCB
the Y SUS Board and FL111 and FL112 on the
Control Board for Control Board operation
Auto Gen
verification.
P101
D201 15V and 5V
Short across the two points labeled
Auto Gen to generate a test pattern.
P161 P162
If the complaint is no video and
shorting the points (AutoGen) causes
3.3V 3.3V
video to appear suspect the Digital PCB.
X-Drive
Signals
Va
Note: 3.3V for X boards originates
P232 P331 P311
from IC221 on the Control board
P206
P301
TCP TCP
P2
Pin Label STBY Run
1 0V 0.79V
Z SUS Dn
2 Z SUS Up 0V 0.13V
3 Z ER Up 0V 0.19V
4 0V
Z ER Dn 0.4V
5 0V 1.9V
Z Bias
6
Z Enable 0V 0.8V
Z Ramp Dn 1.9V
7 0V
Gnd Gnd Gnd
8
9
Gnd Gnd Gnd
10
+5V 4.9V
0V
11 +15V 16.9V
0V
+15V 0V 16.9V
12
P813
Z-Drive Signals
P301
IC305
P1001
To keys and IR
P1005
To Speakers
Reset
12 Meg
MAIN PCB
Grayed Out ICs are located on Back
P304
P302 P303
TCP TCP TCP
Z-SUS
41V (AC) rms 400us 200Vp/p
Z-SUSTAIN
P6
Z-SUS
Waveform
TP J27
VZB TP
+
Right Side
VZB
R49 or R50
VR8
P3
To Chassis
P7
Gnd
P2
5V
17V
Note: P1002 only
LVDS
uses first 26 pins.
IC305
IC304 1) 4.9V
P1002 P1004
2) 3.29V
3) 0V
25 Meg
LVDS plugs into
IC304
Only at
IC1 far left side
1) 3.28V
Boot up
2) 1.86V
X1 Micro
3) 0.6V
X501
IC502
IC502
1) 0V
Pin 19
2) 0V
3) 0.3V
Tuner
19) Video
Pin 1
16) Audio
TUNER
4) 5V
RIGHT X DRIVE
P306
P305
TCP TCP