Troubleshooting - Sharp CD-C492 Service Manual

When the CD does not function
When the CD section does not operate When the objective lens of the optical pickup is dirty,this section may not operate.Clean
the objective lens,and check the playback operation.When this section does not operate even after the above step is taken,check
the following items.
Remove the cabinet and follow the troubleshooting instructions.
"Track skipping and/or no TOC(Table Of Contents) may be caused by build up of dust other foreign matter on the laser pickup lens.
Before attempting any adjustment make certain that the lens is clean. If not, clean it as mentioned below."
Turn the power off.
Gently clean the lens with a lens cleaning tissue and a small amount of isopropyl alcohol.
Do not touch the lens with the bare hand.
• When the turntable fails to stop.
5V
Is from 5 V till 2.5V down pulse (approx. 300 ms)
2.5V
0V
input into the ICF01 pin 84 when the turntable is rotating?
Is there following voltage input on the ICF01 pin 84 in the
specific state?
When the CD mechanism is moved up: 0V
In other states: 4.3V
Check IC2 pin26 Q91 and Q93 and the periphery.
ICF01 defective.
• When turntable fails to move.
Is there following voltage input on the ICF01 pin 85 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?
Is 4V output from the Q91 emitter during operation stated
above?
Check turntable motor and turntable mechanism.

TROUBLESHOOTING

Yes
Yes
Yes
Yes
Yes
Yes
Check the SW3 and the wiring from the ICF01 pin 84 to the
No
SW3.
Check the MECHA UP SW and the wiring from the ICF01 pin
No 85 to the MECHA UP SW.
Check the MECHA UP SW and the wiring from the ICF01 pin
85 to the MECHA UP SW.
No
Check the wiring of IC2 pin 26 and Q93 pin 2.
No
Check Q91, Q93 and the periphery.
No
– 55 –
CD-C492/492C
OK
IC2 defective.