Sharp XL-HP500 Service Manual - Page 36

XL-HP500 (1) Focus-HF system check. Although a CD is inserted and the cover is closed, "NO DISC" is displayed. Press the Tray1 CD Eject Button (SW723) without inserting a disc, and try starting the playback operation. Stopped CH1=500 mV DC 10:1 T FDO 1 CH3=500 mV DC 10:1 500 ms/div (500 ms/div) NORM:20 kS/s No 1. Does the pickup move to the PICKUP-IN Switch (SW4) position ? Yes 2. Does the focus (lens) move up and down ? No (Waveform drawing Figure 36-1) Yes No 3. Is the laser lit ? Yes No 4. Is the turntable rotating ? TDO 3 =Filter= Smoothing : ON BW : FULL =Offset= CH1 : 0.000 V CH2 : 0.0 V CH3 : 0.000 V CH4 : 0.00 V CH1 v/DIV 500 mV =Record Length= Main : 100 K Zoom : 2 K =Trigger= Mode : AUTO Type : EDGE CH1 Delay : 0.0 ns Hold off : 0.2 µs Sled motor (M2). Figure 36-1 Check the focus peripheral circuit. Check the laser diode driver Q1 peripheral circuit. Spindle motor (M1). When a disc is loaded, start playback operation. 1. Is focus servo activated ? (Waveform drawing Figure 36-2) No Pins 7~11, 79 and 80 on IC1 Check the laser diode driver Q1 peripheral circuit. Yes 2. Does DRF change from "L" to "H" ? Yes 3. Is the HF waveform normal ? (Waveform drawing Figure 36-3) Stopped CH1=500 mV DC 10:1 CH2=10 V DC 10:1 CH3=1 V DC 10:1 FDO 1 No No Is the disc rotating ? Check the spin system. If the disc is spinning and a HF waveform is generated, DRF will go H. No If the level is not normal. 500 ms/div (500 ms/div) NORM:20 kS/s T 2 DRF TE 3 CH Position To -3 div -1 div 0 div +1 div +3 div =Filter= =Offset= =Record Length= Smoothing : ON CH1 : 0.000 V Main : 100 K BW : FULL CH2 : 0.0 V Zoom : 2 K CH3 : 0.00 V CH4 : 0.00 V CH2 Position 0.20 div =Trigger= Mode : AUTO Type : EDGE CH1 Delay : 0.0 ns Hold off : 0.2 µs Figure 36-2 - 36 - Figure 36-3 Vp-p=1.0 V~1.3 V 0.5 mV/div,0.5 µsec/div