System Part - LG BH5140S Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

4. SYSTEM PART

Power On.
YES
"WELCOME"
Display on FLD OK?
YES
"LG Logo"
Display on monitor OK?
YES
"LG Logo"
display on monitor oK?
YES
System part OK.
4A
IC101
NO
3.3VA_MICOM, 3.3 V OK?
YES
X101
20.000 MHz OK ?
YES
Replace IC101 UPD78F1164GF.
3.3 VA, FL+, FL- OK?
YES
VFD_STB, VFD_CLK,
VFD_RX OK?
YES
Check DIS301.
IC501 VCC 1.2 V, 1.5 V,
NO
3.3 V OK?
YES
X501
27.000 MHz OK?
YES
IC504
NF_ALE, NF_CLE OK?
YES
Replace IC501 MT8560 or
IC502, IC503.
Proper assemble MAIN and
NO
FRONT PCB OK?
YES
4A
2-44
NO
Check D101 and SMPS board.
NO
Replace X101.
MAIN BOARD
Check Q303, Q308 and
NO
SMPS board.
NO
Check IC101 and CN305.
TIMER BOARD
Check IC153, IC155 and
NO
SMPS board.
NO
Replace X501.
NO
Replace IC504. (NAND Flash)
NO
Assemble properly.