LG 55EF9500 User manual

2015 (EF Series) OLED SMPS Testing
Forcing on the Power Supply
Testing the Power Supply
55EF9500
65EF9500
Updated 03
-
16
-
2016 ver2
1
Updated
03
16
2016
ver2

When servicing an OLED TV and you need to Test the Power Supply, due to the symptoms the TV Won’t Come On or
TV Intermittent Powers Off, before beginning the Power Supply Testing READ THE BELOW FIRST.
Read First Before Beginning the Power Supply Testing Procedure
Check the Front Power Indicator:
Take note of the front Power LED. If it begins to “Blink” (about once a second) continually for 30 seconds and the TV
makes no attempt to turn on, it means that the Main board is “Latched” and no functions work.
If this happens, the Main board will not function again normally until it is unlatched even if the Main board is placed in
another identical OLED model
another
identical
OLED
model
.
To Unlatch the Main Board:
Press the “Power Only” button using the Service Remote. This will place the TV into P-Only mode. P-Only = TV comes
on in Full White Raster. A P-Only black box with text appears in the upper left hand side of the screen. P-Only mode
will also b
yp
ass the “Burn Det” circuit
,
which will allow the TV to turn on normall
y
.
yp
_
,y
If the TV Comes on Normally in P-Only Mode:
Press Exit on any remote and the screen is not full white raster. Press the “In-Start” button and enter the Service
Menu. Scroll down to “Power_Off_History” and look at the events that shut off the TV. If you find three consecutive
“INV_ERROR” this indicates activation of the Burn_Det circuit which is what “Latched” the Main board. If this is the
fS f “
Off /
”
case, look
f
or the
S
ervice Bulletin
f
or this model;
“
Improved Auto Power
Off
/
No Power issue
”
. This bulletin requires
you to update the Software via USB only.
If the TV Still Won’t Come On:
In this case follow the Power Supply Testing, check the Main board. If both are OK, replace the Panel.
If the OLED TV Shuts Off Intermittently:
With the OLED turned on, press the “In-Start” button and enter the Service Menu. Scroll down to “Power_Off_History”
and look at the events that shut the TV off. If you find “PWR_OFF_by_20V_DET or PWR_OFF_by_INV_ERROR”, look for
the Service Bulletin for this model; “Improved Auto Power Off / No Power issue”. This bulletin requires you to update the
Software via USB onl
y
.
2
y
If the TV Still Continues to Intermittently Shut Off:
In this case follow the Power Supply Testing, check the Main board. If both are OK, replace the Panel.

AC Should not be applied at any time while adding jumpers or While
unplugging connectors,
damage to the circuit
Board may
occur.
SMPS TEST 1
Top Row pins
Fig 1
P201
TEST 1 (OLED EF Series) Power Supply Board 12V/24V to Main Voltage Check
unplugging
connectors,
damage
to
the
circuit
Board
may
occur.
I) When AC is applied, the SMPS “MUST” be producing
STBY 3.5V (3.52V) on pins 5 and 7, 8 of P201.
If 3 5V Standby is not being generated the SMPS is defective
Top
Row
pins
are Odd numbers
17
18
24V 24V
12V ON
23 24
21 22
19 20
24V
24V
If
3
.
5V
Standby
is
not
being
generated
,
the
SMPS
is
defective
and may need to be replaced. Make sure AC is arriving at the connector SK100
and +3.5V_ST is not loaded down by the Main Board or the Joy Stick/IR Board.
Remove connector on Main board. If STBY is still missing, SMPS is defective.
II
)
Unplug
P2399
on the Main Board to make insertion of the Jumpers easier
17
18
15 16
13 14
11 12
12V
12V
12V
12V
_
ON
12V
12V
II
)
Unplug
P2399
on
the
Main
Board
to
make
insertion
of
the
Jumpers
easier
.
Use P2399 side to insert jumpers.
TEST 1: TESTING THE POWER SUPPLY TURN-ON CIRCUIT. (See Fig 1)
(1)
Add
a
jumper (
A
)
between (3 5V STBY) pin
5
and
(
PWR ON
)Pin1
910
7 8
5 6
STBY 3.5V
STBY 3.5V
STBY 3.5V
Gnd
(1)
Add
a
jumper
(
A
)
between
(3
.
5V
STBY)
pin
5
and
(
PWR
_
ON
)
Pin
1
,
(See Fig 1). Apply AC, this will turn on the SMPS. Relay click will be heard.
Check that the 24V and 12V power supplies to the Main board are turned on,
To Main Board Power:
• P201 (11.96V pins 11-15)
•
P201
(
23 70V
pins
19
22)
DRV_ON
3 4
1 2
PWR_ON
A
•
P201
(
23
.
70V
pins
19
-
22)
(2) Remove AC power
See Next page to Test the Power Supply
’
sT
CON 12V line
No 12V or 24V to T-CON at this time. Pin 1 is Bottom on SMPS
Pin 1 is Top on Main
3
See
Next
page
to
Test
the
Power
Supply s
T
-
CON
12V
line
.
TIP: If you are concerned that you may accidently connect the jumpers in the incorrect locations,
please use a 100 ohm 1/8W resistor instead.

Continue if Test 1 was OK.
Leave original jumper (A) in place.
SMPS TEST 2
Top Row pins
are Odd numbers
Fig 2
P201
23 24
TEST 2 (OLED EF Series) Power Supply Board T-CON 12V Power Check
AC Power is removed at this time.
The T-CON should be connected, SMPS P202 and P203 to T-CON.
TEST 2: T-CON 12V POWER SECTION TEST: 17 18
15
16
24V 24V
12V_ON
21 22
19 20
24V
24V
(3) Add another jumper (B) between (STBY_3.5V) pin 8 and (12V_ON) Pin 18.
(See Fig. 2), Simulating PWR_ON and 12V_ON commands.
(4) Apply AC Power.
15
16
13 14
11 12
9
10
12V
12V
12V
B
12V
12V
(5) Check 12V (11.87V) on pins 7-12 on P202.
T-CON 12V Normal:
a) If normal, the SMPS is OK, T-CON 12V load test OK.
DRV_ON
9
10
7 8
5 6
3 4
STBY 3.5V
A
B
STBY 3.5V
STBY 3.5V
Gnd
T-CON 12V Abnormal:
a) Recheck all connections.
b) Confirm the 12V_ON line pulling up to at least 3V.
c) Check SMPS P202 pins 7-12 for an excessive load, normal diode check
should be 0.48V P202 connected
“
0.50V
”
P203 disconnected.
1 2
PWR_ON
should
be
0.48V
P202
connected
0.50V
P203
disconnected.
Check CN11 pins 8-12 on the T-CON for an excessive load.
Diode check should be “1.04V”. (CN11 unplugged from the SMPS, the
panel can be connected or disconnected).
Note: With Red lead on Chassis ground, reading is 0.41V. TIP: If you are concerned that you
may accidently connect the
jumpers in the incorrect locations
Pin 1 is Bottom on SMPS
Pin 1 is Top on Main
4
See Next page to Test the Power Supply’s T-CON 12V and 24V line.
jumpers
in
the
incorrect
locations
,
please use a 100 ohm 1/8W resistor
instead.

Continue if Test 1 and Test 2 were OK.
Leave jumpers (A) and (B) in place. AC Power is removed at this time.
SMPS TEST 3
Top Row pins
are Odd numbers
Fig 1
P201
23 24
TEST 3 (OLED EF Series) Power Supply Board T-CON 12V and 24V Power Check
The T-CON should be connected, SMPS P202 and P203 to T-CON.
TEST 3: T-CON 24V POWER SECTION TEST:
(
3
)
(
B
)
Add another
j
um
p
er between
(
STBY
_
3.5V
)
p
in 5 and
(
DRV
_
ON
)
Pin 2.
are
Odd
numbers
17 18
24V 24V
12V_ON
21 22
19 20
24V
24V
()
() j p ( _ )p ( _ )
(See Fig. 3), Simulating PWR_ON, DRV_ON and 12V_ON command.
(4) Apply AC Power.
(
5
)
Check 24V on
p
ins 8-14 on P203.
15 16
13 14
11 12
12V
12V
12V
12V
12V
()
p
T-CON 24V Normal:
a) If normal (24.16V), the SMPS is OK, T-CON load test OK.
T-CON 24V Abnormal:
910
7 8
5 6
3
4
STBY 3.5V
A
B
STBY 3.5V
STBY 3.5V
Gnd
a) Recheck all connections.
b) Confirm the DRV_ON line pulling up to at least 3V.
c) Check SMPS P203 pins 8-14 for an excessive load, diode check should
be “0.48V” P203 connected or disconnected.
Check CN5 pins 8
-
14 on the T
-
CON for an excessive load.
DRV_ON
C
3
4
1 2
PWR_ON
A
Check
CN5
pins
8
14
on
the
T
CON
for
an
excessive
load.
(CN5 unplugged from the SMPS, Panel connected). Diode check should be
“OL” (Blk lead on Gnd) 0.38V (Red lead on Gnd).
(CN5 unplugged from the SMPS, Panel disconnected). Diode check
should be “OL” (Blk lead on Gnd) 0.51V (Red lead on Gnd). TIP: If you are concerned that you
may accidently connect the
jumpers in the incorrect locations
Pin 1 is Bottom on SMPS
Pin 1 is Top on Main
5
See Next page to Test the Power Supply’s T-CON 24V line
using a light bulb test jig.
jumpers
in
the
incorrect
locations
,
please use a 100 ohm 1/8W resistor
instead.

In this case, the Power Supply needs to be tested to see if it can supply the T-CON 24V and 12V when loaded.
TEST 4: (2015 EF Series OLED) Power Supply Board T-CON 12V and 24V Power
TEST 4: 24V T-CON POWER LOAD CHECK:
(1) Leave all Jumpers in place on P2399 to P201 of the Power Supply and disconnect CN5 on the T-CON board.
(2) Make a 24V load test jig by using a standard 1157 automobile light bulb, (dual element). Solder two wires from the
buttons on the bottom of the bulb. Do not solder any wire to the actual ground of the bulb. (See Fig 4).
(3) Attach one end of the Jig to the 24V line from P203 pins 8-15 from the SMPS.
(4) Attach the other wire from the Jig to Chassis Ground.
Fig 4
Tip: To make insertion easy, cut the sharp end of a safety pin off
and solder it to each end of the wires coming from the light bulb Jig.
Push one needle end into one of the pins 8-14 of CN5.
Push the other needle end of the wire into any pin 1-7 of CN5.
(5) Apply AC to the power supply, the light bulb should light and remain lit.
Measure the 24V line to confirm it’s correct. The bulb should be bright.
Let the SMPS run for several minutes to confirm its operating correctly.
(Do not let wires or light bulb touch any metal parts).
Note: You can also use two sin
g
le element automotive bulbs
(
each 6W
)
tied in series.
g()
a: If the Light Bulb remains lit, the panel is defective because the T-CON and/or the panel is providing too much of a
load causing the power supply to shut off.
b: If the SMPS shuts off, Replace the Power Supply.
6
TEST 5: 12V T-CON POWER LOAD CHECK:
Note: You can test the 12V to the T-CON line using the same procedure, but you only need one bulb. Use same
bulb, but solder one lead to a button and the other to the case.