Sharp CDC2900 Service Manual - Page 44

CD-C622/C2900 • When the CD tray fails to open or close. Is there following voltage input in specific state of IC701 pin 19? Open state: 0V No Close state: 0V Intermediate state between open state and close state: 4.3V Yes Is H output to IC2 pin 24 or 25 for 7 seconds when the OPEN/ CLOSE key is pressed?IC91 is defective. Replace it. No Yes 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. OK IC2 defective. Is 4V output between IC91 pins 3 and 7 during operation stated above? Yes Check the loading motor (M1) and the loading mechanism. Check the periphery of IC91. No OK IC91 defective. • The CD function will not work. The CD operating keys don't work. Yes Check the CD, DSP, power supply, and 16.93 MHz clock, and reset terminal. Yes Check the waveform of SCK, SO (DATA) and SI (COMM). Yes See if the pick-up is in the pick-up in PICKUP IN SW position. Yes If the items mentioned above are OK, check the main microcomputer IC701. 0.5s 0.50 V IC1 16 FD • The CD operating keys work. Check the Focus - HF system. 0.5s 0.50 V IC1 7 TE Playback can be performed without a disc. Yes Does the pick-up move up and down twice? No Focus search OK Yes Figure 44 Does the output waveform of IC1(16)(FD) match that shown in Fig. 44? No 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 Focus search is performed two times when play operation is done without disc. 1 2 - 44 -