Sharp MS722 Service Manual - Page 42

MD-MS722/C/WMS721W • Abnormal display Is waveform output from CNS 482 pins 1 to 3? Are the pin7 (VCC) and pin 6 (GND) normal? Yes Check for pattern breakage of flexible PWB, check for defects of display microcomputer (replace the display unit). Is waveform output from IC 401 pins 45 to 47? No Yes No Check between IC401 and CNS482. Check the periphery of IC401. • Playback state cannot be set When it has been ascertained that the address up to cluster address is normal in the TEST mode. Is initialization performed normally in case of high- reflection disc playback? No Does the playback time display advance? Yes No Check IC201 and IC202 connection line. Is the lead-in photointerrupter set to OFF when the optical pickup moves to the innermost periphery in NORMAL mode? No (Is TP660 in H level?). Yes Ia an attempt to repeat repeatedly the TOC part performed on the low-reflection disc? No Yes Position check in INNER mode Check the lead-in photointerrupter, mechanical flex PWB soldering and CNS601 connection. Replace the disc. • Audio playback clrcult Although the playback time display is acting., no sound is given during playback in the normal mode. Is audio wavefrom output from IC501 pins 19 and 20? Check IC201 pins 70 to 72, pin 74 and IC501 pins 9, 10, 11, No 15 Yes Is audio wavefrom output from IC703 pins 18 and 19. Yes Is audio wavefrom output from J703 pins 3 and 4. Yes Check the pins 5 and 6 of IC703. No Check whether there is defective solder joint of audio signal No line between IC703 and J703 Check headphones jack,and periphery of headphone. - 42 -