CD-C621H (serv.man16). Trouble shooting flow charts - Sharp Audio Service Manual (repair manual)

– 38 –

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.

Dust gradually accumulates on the objective lens during use, and it may degrade performance.
To avoid this problem, use a cleaning disc designed for CD optical pickup lenses.

1. Using the brush in the cleaner cap, apply 1 or 2 drops of the cleaning fluid to the brush on the CD cleaner disc which has

the mark next to it.

2. Place the CD cleaner disc onto the CD disc tray with the brush side down, then press the play button.
3. You will hear musicfor about 20 seconds and the CD player will automatically stop. If it continues to turn, press the stop button.

The CD lens cleaner should be effective for 30 - 50 operations, however if the brushes become worn out earlier then please
replace the cleaner disc.
If the CD cleaner brushes become very wet then wipe off any excess fluid with a soft cloth.
Do not drink the cleaner fluid or allow it to come in contact with the eyes. in the event of this happening then drink and / or
rinse with clean water and seek medical advice.
The CD cleaner disc must not be used on car CD player or on computer CD ROM drives.
All rights reserved. Unauthorized duplicating, broadcasting and renting product is prohibited by law.

Cleaning Disc
PARTS CODE:
    UDSKA0004AFZZ

Cleaner Liquid

– 39 –

•  When the turntable fails to stop.

Is from

  5 V till 2.5V down pulse (approx. 300 ms)

Check the SWM3 and the wiring from the IC701 pin 21 to the
SWM3.

No

No

input into the IC701 pin 21 when the turntable is rotating?

5V

2.5V

0V

Yes

Check IC2 pin26 Q91 and Q93 and the periphery.

Check the MECHA UP SW and the wiring from the IC701 pin
21 to the MECHA UP SW.

No

Yes

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

Yes

Is there following voltage input on the IC701 pin 21 in the
specific state?

In other states: 4.3V

When the CD mechanism is moved up: 0V

Check the MECHA UP SW and the wiring from the IC701 pin
21 to the MECHA UP SW.

Is 4V output from the Q91 emitter during operation stated
above?

Yes

Yes

Check the wiring of IC2 pin 26 and Q93 pin 2.

OK

No

No

Is L output from the IC2 pin 26 during SEC when the disc skip
switch is pressed?

Yes

Check turntable motor and turntable mechanism.

Check Q91, Q93 and the periphery.

IC701 defective.

IC2 defective.

– 40 –

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

Is H output to IC2 pin 24 or 25 for 7 seconds when the OPEN/
CLOSE key is pressed?IC91 is defective. Replace it.

Is 4V output between IC91 pins 3 and 7 during operation
stated above?

Check the loading motor (M1) and the loading mechanism.

Yes

Yes

Yes

No

No

IC2 defective.

No

Check the periphery of IC91.

IC91 defective.

OK

OK

Check the OPEN CLOSE SW and the wiring from the IC701
pin 19 to the OPEN CLOSE SW.

Check the wiring of the IC2 pins 24 and 25, IC91 pins 1 and 3.

The CD operating keys don't work.

Check the CD, DSP, power supply, and 16.93 MHz clock, and
reset terminal.

Check the waveform of SCK, SO (DATA) and SI (COMM).

Yes

Yes

See if the pick-up is in the pick-up in PICKUP IN SW position.

If the items mentioned above are OK, check the main
microcomputer IC701.

Yes

Yes

No

Yes

No

Check the Focus - HF system.

Playback can be performed without a disc.

Focus search OK

Does the pick-up move up and down twice?

Does the output waveform of IC1(16)(FD) match that shown in
Fig. 40?

Check the IC1(50)(CLK) line, 4MHz.
Check the microcomputer data on pins (51)(CL), (52)(DAT)
and (53)CE.

Check the area around IC5-CNP2.

Yes

Yes

Focus search is
performed two
times when play
operation is done
without disc.

 0.5s
0.50 V
IC1  16  FD

2

1

 0.5s
0.50 V
IC1   7  TE

– 41 –

Is HF waveform normal (see the Fig.41-1, 2)?

Check the tracking system.

Is the Focus servo active? (Can you hear it working?)

Check the laser diode driver.
Check the area around IC1(16) - (21) (focus servo circuit).

No

Yes

Yes

Yes

Does the DRF signal change from "L" to "H"?

No

Yes

If the disc is not turning, the DRF
should not change to "H".

Level is abnormal.

No

Yes

Waveform is unstable.

Check the spin system.

Yes

Check the periphery of
IC1 pins 41 and 42.

Check the spin system.

Waveform in case of
normal play-back

HF
1.0V/DIV
0.5

µ

sec/DIV(DC)

(When playing
 back the disc)

3

2
1

4

 0.5s
1.00 V
IC1  16  FD

 0.5s
10.0 V
IC2  13  CLV+

 0.5s
10.0 V
IC1  54  DRF

 0.5s
2.00 V
IC1   7   TE

Check waveform of IC1 pin 7 (TE).

Play is possible in
TEST mode.

Although IL is possible,
play is impossible.

Check the periphery
of IC 1 pin 14.

Normal jump is impeded,
and the program top
cannot be reached.

Check the periphery of IC 1
pin 8 to pin 15, and IC 5 to
CNP2.

The waveform shown in
Fig.41-3 appears, and no-
disc state appears soon.

Tracking servo is
inoperative.

Yes

Yes

Yes

Yes

Yes

Data  cannot be read.

Check the VCO-PLL system.

Yes

3

4

  5ms
1.00 V
IC1   7   TE

  5 ms
5.0 V
IC1  54  DRF