Read LG 42LG61YD (CHASSIS:LB81C) Service Manual online
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1. TV/CATV doesn’t display
2. DTV doesn’t display
TROUBLESHOOTING
Check T U401 Pin 15(Vid eo ou tp ut),
Pin1 6(Sound output)
Can you see t he normal sign al?
Check th e output of TR(Q503).
Can you see t he normal wavefo rm?
Check th e output of Main IC(IC100).
Esp ecially you sh ould ch eck
The H,V sync and c loc k.
Can you see t he normal wavefo rm?
YES
YES
NO
Could you measu re voltag e of TU800 & IIC
lines?
Are they all normal?
YES
NO
You sh ou ld ch eck p ower lin e
& IIC li nes.
YES
You sh ou ld rep lace TUNER.
NO
You sh ou ld decid e to rep lace TR(Q503) or not.
NO
After ch eckin g th e Power of Main IC(IC100) you
should decide to replace Main IC or not .
This bo ard has b ig problem becau se Main
IC(IC100) have some troubles.
Afte r c hecking thoro ugh ly all pa th onc e again,
You sh ou ld decid e to rep lace Main Bo ard or no t.
Check th e outp ut data o f TU800 Pin 24~34
Can you see t he normal sign al?
NO
Could you measu re voltag e of TU800 & IIC
lines?
Are they all normal?
NO
You sh ou ld ch eck p ower lin e
& IIC li nes.
YES
You sh ou ld rep lace TUNER.
YES
Check th e output of Main IC(IC100).
Esp ecially you sh ould ch eck
The H,V sync and c loc k.
Can you see t he normal wavefo rm?
YES
NO
After ch eckin g th e Power of Main IC(IC100) you
should decide to replace Main IC or not .
This bo ard has b ig problem becau se Main
IC(IC100) have some troubles.
Afte r c hecking thoro ugh ly all pa th onc e again,
You sh ou ld decid e to rep lace Main Bo ard or no t.
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