When Turntable Fails To Move; When The Cd Tray Fails To Open Or Close; The Cd Function Will Not Work - Sharp CD-PC1881V Service Manual

• When turntable fails to move.

Is there following voltage input on the IC701 pin 21 in the
specific state?
When the CD mechanism is moved up: 0V
In other states: 4.3V
Is L output from the IC2 pin 26 during SEC when the disc skip
switch is pressed?
Check turntable motor and turntable mechanism.

• When the CD tray fails to open or close.

Is there following voltage input in specific state of IC701 pin 19?
Open state: 0V
Close state: 0V
Intermediate state between open state and close state: 4.3V
Yes
Is H output to IC2 pin 24 or 25 for 7 seconds when the OPEN/
CLOSE key is pressed?IC91 is defective. Replace it.
Yes
Check the loading motor (M1) and the loading mechanism.

• The CD function will not work.

The CD operating keys don't work.
Yes
Check the CD, DSP, power supply, and 16.93 MHz clock, and
reset terminal.
Yes
Check the waveform of SCK, SO (DATA) and SI (COMM).
Yes
See if the pick-up is in the PICKUP IN SW position.
Yes
If the items mentioned above are OK, check the main
microcomputer IC701.
Yes
Yes
Check the MECHA UP SW and the wiring from the IC701 pin
21 to the MECHA UP SW.
No
Check the wiring of IC2 pin 26.
No
Check the OPEN CLOSE SW and the wiring from the IC701
No
pin 19 to the OPEN CLOSE SW.
Check the wiring of the IC2 pins 24 and 25.
No
IC2 defective.
– 41 –
CD-PC1881V
OK
IC2 defective.
OK