Sharp CD-C471 W Service Manual page 41

Is there following voltage input in specific state of IC701 pin 53?
Open state: OV
Close state: OV
Intermediate state between open state and close state: 5V
I
Yes
Is H output to IC2 pin 24
CLOSE key is pressed?lC81 is defective. Replace it.
Is 4V output between IC81 pins 3 and 7 during operation
stated above?
Yes
Check the loading motor (M3) and the loading mechanism.
The CD operating kevs don' t work.
Check the CD, DSP, power supply, and 16.93 MHz clock, and
reset terminal.
See if the pick-up is in the PICKUP IN SW position.
If the items mentioned above are OK, check the main
microcomputer IC701.
Check the Focus - HF system.
Playback can be performed without a disc.
Does the pick-up move u
Does the output waveform o
Fig. 4l?
I
Check the microcomputer data on pins (51)(CL), (52)(DAT)
Yes
Yes
No
No
pin 53 to the OPEN CLOSE SW.
Check the wiring of the lC2 pins 24 and 25, IC81 pins 1 and 3.
Check the periphery of IC81.
No
0.50
0.50 v
Focus search OK
Check the area around IC3-CNP2.
CD-C471 W
I
Figure 41