Sharp CD-C440W Service Manual page 39

• When the CD tray fails to open or close.
Is there following voltage input in specific state of IC801 pin 53?
Open state: 0V
Close state: 0V
Intermediate state between open state and close state: 5V
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
Is 4V output between IC91 pins 3 and 7 during operation
stated above?
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 pick-up in PICKUP IN SW position.
Yes
If the items mentioned above are OK, check the main
microcomputer IC801.
• The CD operating keys work.
Check the Focus - HF system.
Playback can be performed without a disc.
Yes
Does the pick-up move up and down twice?
No
Does the output waveform of IC1(16)(FD) match that shown in
Fig. 39?
No
Check the IC1(50)(CLK) line, 4MHz.
Check the microcomputer data on pins (51)(CL), (52)(DAT)
and (53)CE.
All manuals and user guides at all-guides.com
No
No
No
Yes
Yes
– 39 –
Check the OPEN CLOSE SW and the wiring from the IC801
pin 53 to the OPEN CLOSE SW.
Check the wiring of the IC2 pins 24 and 25, IC91 pins 1 and 3.
IC2 defective.
Check the periphery of IC91.
IC91 defective.
0.5s
0.50 V
IC1 16 FD
0.5s
0.50 V
IC1 7 TE
Figure 39
Focus search OK
Check the area around IC5-CNP2.
CD-C440W/CP-C440W
OK
OK
Focus search is
performed two
times when play
operation is done
without disc.
1
2