Power Supply On Main Board - LG BH4120SN Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

3. POWER SUPPLY ON MAIN BOARD

No 3.3 V.
Is the VCC 3.8 VA supplied to IC151 pin3?
Is there 'H' signal at IC153 pin2?
Check IC151 and replace.
No 5 V.
Is the VCC 6 VA supplied to IC153 pin2?
Is there 'H' signal at IC153 pin1?
Check IC153 and Replace.
No 1.2 V.
Is the VCC 14 VA supplied to IC155 pin2?
Is there 1.2V at IC155 pin8?
Check IC155 and replace.
No 1.5 V.
Is the VCC 14 VA supplied to IC150 pin13?
Is there 1.5 V at IC150 pin12?
Check IC150 and replace.
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
Check 3.8 VA on SMPS Board.
NO
Check IC101 pin58 (DCDC33_CTRL).
NO
Check 6 VA on SMPS Board.
NO
Check IC101 pin68 (LDO_CTRL).
NO
Check 14 VA on SMPS Board.
NO
Check IC101 pin68 (LDO_CTRL).
NO
Check 14 VA on SMPS Board
NO
Check IC101 pin59 (DCDC15_CTRL).
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