42PM4M-WA (CHASSIS:PM75A) - LG TV Service Manual (repair manual). Page 8

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ADJUSTMENT INSTRUCTIONS
8. Method of D-BOX(LST-4100B) Check
- Use the cables nd D-Box below for D0box check.
8-1. Method of D-Box Connection
(1) Connect Power to 
(2) Connect 
to SET or JIG AC-IN
(3) Refer to above picture and then, Connect RS-232C and
HDMI cable.
8-2. D-Box Check Method
(1) After D-Box connection, Press menu key on D-Box
Remote controller.
(2) When below picture is displayed on the screen, D-box
check is done.
9. POWER PCB Assy Voltage
Adjustments 
(Va, Vs Voltage adjustments)
9-1. Test Equipment :
Stick for adjustment
D.M.M. 1EA
9-2.Connection Diagram for Measuring
: refer to Fig. 5
9-3. Adjustment Method
(1) Adjustment method for Power board
After Changing RF snow noise.
(2) Va Adjustment
1) After receiving 100% Full White Pattern, HEAT RUN.
2) Connect + terminal of D.M.M to Va pin of P812, connect
- terminal to GND pin of P812).
3) After turning VR901, voltage of D.M.M adjustment as
same as Va voltage which on label of panel right/top.
(Deviation; ±0.5V)
(3) Vs Adjustment
1) Connect + terminal of D.M.M to Vs pin of P812, connect
– terminal to GND pin of P812.
2) After turning VR951, voltage of D.M.M adjustment as
same as Va voltage which on label of panel right/top.
(Deviation; ±0.5V)
(1) LST-4100B
D-box
(2) RS-232C
(male to male)
(3) HDMI
1EA
(4) Power Cord
2EA
Each PCB assembly must be checked by check JIG set.
(Because power PCB Assembly damages to PDP Module,
especially be careful)
(Fig. 5) Connection diagram of power adjustment for measuring
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