Sharp CDC2900 Service Manual - Page 46

Checking the spin system., Checking the VCO-PLL system, Although HF waveform is normal

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Page 46 highlights

CD-C622/C2900 • Checking the spin system. Play operation is performed without disc. Yes The turntable rotates a little. No The turntable fails to rotate or rotates at high speed. Yes The spin driver circuit is normal. Yes Check the periphery of IC1 pins 23 to 27, pin 39, and pin 40, IC2 pin 12 and pin 13, IC5 to CNP3. • Checking the VCO-PLL system Play operation is performed when disc exits. Yes Although HF waveform is normal, TOC data cannot be read. Yes Check PDO waveform (Fig. 46). Abnormal Check the IC1 pins 43 and 44, IC2 pins 3, 5, 7, 10, and 11. 0.5s 1.00 V IC2 3 PDO 0.5s 1.00 V IC2 16 FD Stop --> Play As VCO frequency is locked at 4.32 M Hz, voltage of PDO rises and stabili- zes. 2 3 Figure 46 • Although HF waveform is normal and the time indication is normal, no sound is emitted. Check IC 2 pin 48 (EFLG). Yes Check IC2 pins 37, 40. Abnomal Check IC 401 and POWER AMP IC 801. No Usually, the number of pulses of flawless disc is 100 pulses/sec or less. - 46 -

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CD-C622/C2900
– 46 –
•
Checking the spin system.
Yes
No
Play operation is performed without disc.
The turntable rotates a little.
The turntable fails to rotate or rotates at high speed.
Yes
The spin driver circuit is normal.
Check the periphery of IC1 pins 23 to 27, pin 39, and pin 40, IC2
pin 12 and pin 13, IC5 to CNP3.
Yes
•
Checking the VCO-PLL system
Figure 46
Play operation is performed when disc exits.
Yes
Although HF waveform is normal, TOC data cannot be read.
Yes
Check PDO waveform (Fig. 46).
Abnormal
Check the IC1 pins 43 and 44, IC2 pins 3, 5, 7, 10, and 11.
Stop --> Play
As VCO freque-
ncy is locked at
4.32 M Hz, voltage
of PDO rises and
stabili- zes.
2
3
0.5s
1.00 V
IC2
3
PDO
0.5s
1.00 V
IC2
16
FD
•
Although HF waveform is normal and the time
indication is normal, no sound is emitted.
Check
IC 2 pin 48 (EFLG).
Check IC2 pins 37, 40.
Check IC 401 and POWER AMP IC 801.
Abnomal
Yes
Usually, the number of pulses of flawless disc is 100 pulses/sec
or less.
No