LG LST-4200A Service Manual - Page 17

(4) No 5.0VA Is there about 5.4V at the IC152 pin1? YES Is there about 3.3V~ 5V NO at the IC152 pin4? YES Check the IC152 NO and Replace Check or Replace the D106 Check the 'PWR CTL "H"' signal from µ-com (5) No 9V No 9V YES Is there about 13V NO at the IC154 pin1? YES Is there about 3.3V~ NO 5V at the IC154 pin4? YES Check the IC154 and Replace Check or Replace the D109 Check the 'PWR CTL "H"' signal from µ-com (6) No 3.3V No 3.3V YES Is there about 3.8V NO at the IC153 pin1? YES Is there about 3.3V~ NO 5V at the IC153 pin4? YES Check the IC153 and Replace Check or Replace the D105 Check the 'PWR CTL "H"' signal from µ-com (7) No 12V No 12V YES Is there about 13V NO at the IC155 pin1? YES Is there about 3.3V~ NO 5V at the IC155 pin4? YES Check the IC155 and Replace Check or Replace the D109 Check the 'PWR CTL "H"' signal from µ-com 3-8