Sharp MD-MT877S Service Manual page 39

• Abnormal display.
Is waveform output from CN451 pins 3 to 5 ?
Are the pin 2 (VCC) and pin 12, 13 (GND) normal ?
Check for pattern breakage of flexible PWB, check for
defects of display microcomputer (replace the display unit).
• Audio playback clrcult.
In the normal playback mode, LCD play time display functions, but no audio is heard.
Is audio waveform output from IC501 pins 15 and 16 ?
Is audio waveform output from IC703 pins 8 and 17.
Is audio waveform output from J703 pins 3 and 4.
Check headphones jack, and periphery of headphone.
• The spindle motor fails to run. Does the head move.
Does the waveform appear on the IC201 pins 24 and 25 after
TEST mode AUTO2 completion and in this state ?
Does waveform appear on the IC601 pin 15 ?
Does waveform appear on IC601 pins 7, 10 and 12 ?
Replace the spindle motor.
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Is waveform output from IC401 pins 31 to 33 ?
No
Yes
Check between IC401 and
CN451.
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 for defective solder joint of audio signal line between
IC703 and J703.
No
Check the IC201 periphery.
No
Replace IC601.
No
L608, IC201, IC601, CN601 and flex, etc. soldering check.
No
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MD-MT877/MD-MT877C
No
Check the periphery of IC401.