A preliminary inspection on the power supply first, found the power supply has to work. Then check TB1237AN voltage 3 feet, incredibly to 0 v, 17 feet voltage of 0 v. Because of three feet and 17 feet using three-terminal voltage regulator circuit IC882 (AN7809) power supply (not draw the circuit), so the inspection on IC882, found IC882 input voltage is normal, but no voltage output, doubt IC882 damage, after replacement, troubleshooting.dm9service manual download site