Abnormal Display; Playback State Cannot Be Set; Audio Playback Clrcult - Sharp MD-MT831H(GL) Service Manual

MD-MT831H/W

• Abnormal display

Is waveform output from CN451 pins 1 to 3?
Are the pin10 (VCC) and pin 6 (GND) normal?
Check for pattern breakage of flexible PWB, check for
defects of display microcomputer (replace the display unit).

• 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?
Is the lead-in photointerrupter set to OFF when the optical
pickup moves to the innermost periphery in NORMAL mode?
(Is TP662 in H level?).
Ia an attempt to repeat repeatedly the TOC part performed
on the low-reflection disc?
Position check in INNER mode

• 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?
Is audio wavefrom output from IC703 pins 8 and 17.
Is audio wavefrom output from J703 pins 3 and 4.
Check headphones jack,and periphery of headphone.
Yes
No
Yes
Yes
Yes
Yes
Yes
Is waveform output from IC401 pins 9,11,13?
No
Yes
Check between IC401 and
CN451.
Does the playback time display advance?
Yes
Check IC201 and IC202 connection line.
Check the lead-in photointerrupter, mechanical flex
PWB soldering and CN601 connection.
No
Replace the disc.
No
Check IC201 pins 70 to 72, pin 74 and IC501 pins 9, 10, 11,
15
No
Check the pins 4 and 21 of IC703.
No
Check whether there is defective solder joint of audio signal
line between IC703 and J703
No
– 38 –
No
Check the periphery of IC401.
No