Sharp MD-MT80W(S) Service Manual page 40

MD-MT80W/90W/90/90C
• Abnormal display
Is waveform output from CN482 pins 6 to 8?
Are the pin 4 (VCC) and pin 5 (GND) normal?
Yes
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?
No
Is the lead-in photointerrupter set to OFF when the optical
pickup moves to the innermost periphery in NORMAL mode?
(Is TP654 in H level?).
Yes
Is an attempt to repeat repeatedly the TOC part performed
on the low-reflection disc?
Yes
Position check in INNER mode
• Audio playback circuit
Although the playback time display is acting., no sound is given during playback in the normal mode.
Is audio waveform output from IC501 pins 15 and 16?
Yes
Is audio waveform output from IC703 pins 8 and 17.
Yes
Is audio waveform output from J703 pins 3 and 4.
Yes
Check headphones jack, and periphery of headphone.
Is waveform output from IC401 pins 9,11,13?
No
Yes
Check between IC401 and
CN482.
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,
12.
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
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No
Check the periphery of IC401.
No