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LH40/LH55 Trouble shooting guide – RGB PC

Check JK1201
Can you see the normal waveform?

YES

JK1201 may have problem. Replace this Jack.

NO

Check the input (Pin K1,K2,K3,L1,L3)
of LGE3159(IC100).
Measure waveform at C113,C114,C108 and R146,R149
because it’s more easy to check.
Can you see the normal waveform?

Video

NO

YES

YES

Check all power domain of LGE7329 (IC801)
(3.3V, 1.9V_CORE,1.26V) 

& crystal output (X800 / 12MHz)&FRC_RESET

Measure Power & waveform at L800,L801,L802,L803,
L804,L806
because it’s more easy to check.
Can you see the normal waveform?

This board has big problem because FRC chip(LGE7329) have some troubles.
After checking thoroughly all path once again, You should decide to replace 
LGE7329.
Although you replace it, you cannot see normal display, decide to replace 
Main chip(LGE3159)

This board has big problem because Main chip(LGE3159) have some troubles.
After checking thoroughly all path once again, You should decide to replace LGE3159 or not.

LH40/LH55 Trouble shooting guide – HDMI

Check input connect JK500,JK501,JK502,JK503
Can you see the normal waveform?

Check DDC communication lines
(IC502)

JK500,JK501,JK502,JK503 may have problem. Replace this Jack.

Check the output of TDA9996HL(IC502)
_HDMI1,2,3 or HDMI4. . 
Can you see the normal waveform?

After checking the Power of this chip, you should decide to replace this or not.

Check HDCP communication lines(IC105)

After checking the Power of this chip, you should decide to replace this or not.

YES

YES

YES

NO

NO

NO

Video

NO

YES

YES

Check all power domain of LGE7329 (IC801)
(3.3V, 1.9V_CORE,1.26V) 

& crystal output (X800 / 12MHz)&FRC_RESET

Measure Power & waveform at L800,L801,L802,L803,L804,L806
because it’s more easy to check.
Can you see the normal waveform?

This board has big problem because FRC chip(LGE7329) have some troubles.
After checking thoroughly all path once again, You should decide to replace  LGE7329.
Although you replace it, you cannot see normal display, decide to replace Main chip(LGE3159)

This board has big problem because Main chip(LGE3159) have some troubles.
After checking thoroughly all path once again, You should decide to replace LGE3159 or not.

LH40/LH55 Trouble shooting guide – TV/CATV

Check TU1 Pin16(SIF)
Can you see the normal signal?

Check the input (Pin W2) of  LGE3159((IC100).
Measure waveform at C147 because it’s more easy to check.
Can you see the normal waveform?

YES

NO

Could you measure voltage of TU1001 & IIC lines?
Are they all normal?

NO

You should check power line 
& IIC lines.

YES

You should replace TUNER.

NO

After checking audio signal line, you should decide to replace item or not.

Audio(In)

LA92B-LH40/LH55 Trouble shooting guide – AV/Component/RGB-PC

Audio(In)

Check JK1206, JK1202, JK1205
Can you see the normal waveform?

NO

JK701, JK707, JK700, JK702, JK703 may have problem. Replace this Jack.

Check the input (PinAA3,Y1,AE1,AF3,AE3,AE2,AA1
AB1,AB2,AC2,AB3,AC3) of  LGE3159(IC100).
Can you see the normal waveform?

NO

YES

After checking audio signal line, you should decide to replace item or not.

YES

Check the Output (Pin Audio_MASTER_CLK ,MS_LRCK
MS_SCK,MS_LRCH) of  LGE3159(IC100).
Can you see the normal waveform?

NO

After checking audio signal line, you should decide to replace item or not.

Check IC600(NTP-3100L) L606/L607

YES

NO

After checking audio signal line, you should decide to replace item or not.