LG 55EG9600 Training page 21

Power Supply Operation Explained (2 of 2)
(8) Next, the Micro (pin 4) turns on the PANEL_CTL. This line is pulled up by R2321 to (+3.52V). This leave P2399 pin 18 as 12V_ON and arrives on
the SMPS P201 pin 18. This turns on the 12VT to the T-CON. 12VT is output P203 pins 7-12 which arrives at the T-CON board CN11 pins 7-12.
This 12VT is routed through the fuse and turns on the DC-to-DC converters for a variety of voltages for the T-CON board, both operational and
Panel voltages.
(9) The next step for the Micro (pin 19) is to turn on the INV_CTL line, (Inverter Control). This line is pulled up by R2394 to (+3.12V). This high is
routed through R2393. INV_CTL leaves P2399 pin 2 and arrives on the SMPS P201 pin 22 and is now labeled DRV_ON (Drive On). This high is
then routed to the Controller IC. The controller turns on 24VD (Voltage for Display) which is output P202 (pins 8-15) and on to the T-CON board
CN5 (pins 8-15). It is routed through a fuse and out to the Panel itself for the Panel's operational voltage.
NOTE1 (ACD) (AC_DET_OLED on the Main): ACD monitors the AC input to the Power Supply. At Turn On, when AC is available, this pin go
high to 3.33V. This is output P201 pin 4 to P2399 pin 4, routed through R2395 and then sent to IC2307 pin3 which is the "Power_Det" IC. This
keep the output pin 2 Low which is sent to the Microprocessor IC3000 pin 14. If the AC_DET line goes low, IC2307 output a 3.5V high from
pin 2 and into the Microprocessor pin 14. The Microprocessor turn off the TV and enters Power_Off_by_AC_DET into the Power Off Status log.
If the AC_DET line doesn't go high during turn on, the TV will not turn on.
NOTE2 (Panel 20V Loss Detection): The Panel 24VD is monitored by the Main board. There is a line on the Vx1 cable P7100 pin 32 called
"EL_VDD_DETECT_22V". It is routed through R7103 and the name is changed to POWER_DET_1 and sent to the Micro pin 44. This line is
normally 3.2V when the 24VD is normal. If the 24VD is missing or low, this line drops, the TV set shuts off and logs
"POWER_OFF_BY_20V_DET in the Power Off Status menu in IN-START. If 20V_DET is discovered in the Power Off Status, suspect
connection errors between the Power Supply and the T-CON. If all connectors are normal, suspect a loss of "DRV_ON" P201 pin 2 from the
Main P2399 pin 2 INV_CTL, possibly the Connector harness (Intermittent). Also possible the SMPS isn't producing 24VD to the T-CON.
NOTE3 (Panel Burn Detection): The Panel is also monitored by the Main board for "Burn Detection". This indicates an internal short on its grid
lines. There is a line on the Vx1 cable P7100 pin 40 called "T_CON_SYS_POWER_OFF".
This line is routed through R7101 and renamed to "LED_R" sent to the Micro pin 16. This line is normally 0V when the Panel is operating
normally. If the Panel's internal grids short, this line rises to 3.5V, the TV set shuts off and logs "POWER_OFF_BY_INV_ERROR" in the Power
Off Status menu in IN-START.
Additional Note: If the Burn_Det (INV_ERROR) repeats 3 times consecutively when trying to turn on the TV, the Main board will "Lock" and
will no longer turn on the TV, (Even if the Main board were put in a different TV it will still remain locked.
To Un-Lock the Main Board: It has to be turned on by using the service remote "P-Only" button. This by-passes the Burn detection. You can
check the Power off status by pressing "Exit" then entering the In-Start service menu and Scroll to Power Off Status. Look for 3 consecutive
"INV_ERROR" entries. If burn detection is the cause, make sure Software is up to date. If yes the Panel is defective and needs to be replaced.
To "Exit" P-Only mode press "In-Stop" button on the Service remote and now the Main board will be unlocked.
November 2017
Page 05
55EG9600 (2015 OLED) Power Supply
LG