After thorough cleaning Philips VAM1202 laser head test machine, it can play its reading. Check screen supply + 5V, -25V, AC3.5V were normal, the machine screen IC for the NEC's UPD16312GB, check the external circuit without exception, when a fault occurs due to panel buttons are invalid and can only operate with a remote control, so OSD board to measure the motherboard socket CN203 between each terminal voltage, DATA terminal at 4.2V ~ 5.0V volatility, CLK terminal is 4.6V, CS is 5.0V, initially suspected OSD IC bad, replace the same type of screen display IC (D16312GB ) After the test machine, there is still no on-screen, while the new fault, which uses remote control to play the machine, press the "Volume -" button has become the "back" button, but the "return" key is functioning properly ( Note: The remote control is intact, no adhesion and internal key leakage phenomenon), suspected new replacement screen IC has a problem with PT6312LQ D16312GB substitution after replacement after a fault with the first two pins labeled as {Note manner, PT16312LQ is the word for the lower left corner (forward) when the dot mark as a starting 1 foot, counting to 44 feet in a counterclockwise direction; and D16312GB (UPD16312GB) is the word for the upper left corner (forward) when a large dot mark starting 1 foot to 44 feet depending on the number of counterclockwise. Its lower right corner there is also a small dot mark, which is the other starting 1 foot Recognition IC pins are not the same. Suspected motherboard CPU (IC201) section interface function damage, with the same type substitution normal CPU on the machine, the fault persists. Measuring the voltage across the 12MHz crystal are 2.6V, 2.3V, it is normal. Test for ROM (SRAM) test machine, normal screen, part of the remote control function disorders also returned to normal.QGnservice manual download site