Sharp XL-HP737 Service Manual - Page 45
The HF waveform is normal and the time is displayed nor, mally, but no sound is produced. Or
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(4) PLL system check. When a disc is loaded, start play operation. Stopped CH1=500 mV DC 10:1 PDO1 3 XL-HP737 CH3=1 V DC 10:1 1999/04/05 17:33:17 CH4=1 V 500 ms/div DC 10:1 (500 ms/div) NORM:20 kS/s The HF waveform is normal, but the TOC data cannot be read. Check the PDO waveform. (Figure 6) Check around pins 76~80 on IC1. 4 PDO2 T FDO 1 =Filter= Smoothing : ON BW : FULL =Offset= CH1 : 0.000 V CH2 : 0.0 V CH3 : 0.00 V CH4 : 0.00 V CH1 v/DIV 500 mV =Record Length= Main : 100 K Zoom : 2 K =Trigger= Mode : AUTO Type : EDGE CH2 Delay : 0.0 ns Hold off : 0.2 µs Figure 6 (5) Others. The HF waveform is normal and the time is displayed normally, but no sound is produced. Or the sound has dropouts. Is pin 69 (C2F) on IC1 "L" ? No There are too many error flags on a damaged disc which makes error correction impossible. Yes 1. When playing at normal speed. Check the peripheral circuit at pin 39 (DOUT) on IC1 and the waveform (Figure 7). Check again using a known good disc. If OK, Check the unit. Stopped T CH1=2 V DC 10:1 T 1 DOUT 1999/04/07 09:25:28 500 ns/div (500 ns/div) NORM:200 MS/s =Filter= Smoothing : ON BW : FULL =Offset= CH1 : 0.00 V CH2 : 0.00 V CH3 : 0.00 V CH4 : 0.00 V =Record Length= Main : 1 K Zoom : 100 =Trigger= Mode : NORMAL Type : EDGE CH1 Delay : 2.887 ms Hold off : 0.2 µs Figure 7 7 - 4