2-43
ELECTRICAL TROUBLESHOOTING GUIDE
4. SYSTEM PART
MAIN BOARD
TIMER BOARD
Power On.
System part OK.
4A
4A
Replace IC101 UPD78F1165.
Replace IC501 MT8560 or
IC502, IC503.
Proper assemble MAIN and
FRONT PCB OK?
Check DIS301.
“WELCOME”
Display on FLD OK?
“LG Logo”
Display on monitor OK?
“LG Logo”
display on monitor oK?
IC101
3.3VA_MICOM, 3.3 V OK?
IC501 VCC 1.2 V, 1.5 V,
3.3 V OK?
3.3V, FL(+), FL(-) OK?
X101
20.000 MHz OK ?
X501
27.000 MHz OK?
IC504
NF_ALE, NF_CLE OK?
VFD_STB, VFD_CLK,
VFD_RX OK?
Check D101 and SMPS board.
Check IC155, IC150, IC151
and SMPS board.
Check Q303, Q308 and
SMPS board.
Replace X101.
Replace X501.
Replace IC504. (NAND Flash)
Assemble properly.
Check IC101 and CN305.
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
Summary of Contents for BH4120SN
Page 56: ...2 47 WAVEFORMS IC501 MT8560 X TAL 27 MHz 1 1 7 8 10 9 1 SYSTEM PART 1 ...
Page 59: ...2 50 WAVEFORMS H_SDA H_SCL 11 12 5 HDMI PART 12 11 ...
Page 60: ...2 51 WAVEFORMS HDMI_CLK_N 13 13 12 11 14 HDMI_0_N 14 JK803 ...
Page 61: ...2 52 ...
Page 79: ...2 87 2 88 2 MAIN P C BOARD TOP VIEW BOTTOM VIEW ...
Page 80: ...3 AMP P C BOARD TOP VIEW BOTTOM VIEW 2 89 2 90 ...
Page 81: ...4 JACK P C BOARD 5 FRONT P C BOARD TOP VIEW BOTTOM VIEW 2 91 2 92 TOP VIEW BOTTOM VIEW ...
Page 83: ...3 2 ...
Page 87: ...A800 Front SPK A700 Center SPK A600 Rear SPK 4 SPEAKER SECTION 4 1 FRONT CENTER REAR SPEAKER ...
Page 88: ...A900 4 2 PASSIVE SUBWOOFER ...
Page 89: ......
Page 103: ...4 14 MEMO ...