VCD player fault repair examples

Author: Huang Signature/et al
Publisher:
Publish Date: 2004-03-08
Features: This book compiles 263 troubleshooting cases of VCD/DVD players from over 50 brands such as Sony, Sharp, Panasonic, Philips, Hitachi, Hyundai, Samsung, New, Dongpeng, Changhong, Wantech, Master, Xinhua, Xinwang, Xinmash, Yingying, AIDU, and Red Sun. Each case provides detailed information on the model, fault symptoms, analysis, and repair methods. It is characterized by comprehensive content, illustrations, conciseness, and practicality, making it suitable for radio enthusiasts and technicians with junior high or above education.
Excerpt:
Example 3. Unable to play later tracks (poor contact between laser head flexible cable and socket)
[Model] Sony VCPF11 VCD/DVD player.
[Fault Symptom] The player can read discs but only plays the first few tracks. Later tracks cannot be played. When a karaoke disc is inserted, it plays normally up to the 4th track, then the screen displays "NODISC."
[Analysis and Repair] After opening the cover, the spindle rotates normally, and the disc search function works correctly. However, when playing the 4th track, the laser head assembly moves slightly outward and then stops, followed by the spindle stopping and the screen displaying "NODISC." Based on the symptoms, the issue is likely mechanical. The laser head servo gear and rail are checked and found to be normal. Upon further observation, the spindle motor restarts and the image and sound return when the flexible cable connected to the laser head is accidentally touched. This suggests a broken flexible cable. The laser head assembly is removed, and the cable is unplugged and cleaned with alcohol. All circuits are tested and found to be normal. After reinstallation, the machine is turned on, but no red light is produced. Suspecting a damaged laser tube during assembly, the core is disassembled, and the resistance between the 12-pin flexible cable socket contacts is measured. It is found that the F+, F-, and Vcc pins are all open, while the cable alone tests normal. The fault is confirmed to be poor contact between the cable and the socket. Considering only three wires are open, fine and flexible wires are used to bypass the broken connections on the core board. After verification, the machine is turned on, and the fault is resolved.
Example 4. Unable to read discs (laser head bracket deformation)
[Model] Sony VCPS55 VCD/DVD player.
[Fault Symptom] The player fails to read VCD or CD discs, displaying "NODISC."
[Analysis and Repair] After opening the cover, the disc is played. The machine transmits and loads normally, the spindle motor runs correctly, and the laser head performs vertical focusing and radial tracking. However, after two or three movements, the disc is ejected, and the screen displays "NODISC." The laser head's emitted laser intensity is nearly normal. When the laser head stops, the lens is found to be unlevel, indicating deformation of the lens bracket. Replacing the lens bracket restores normal operation. Alternatively, the lens bracket can be adjusted and corrected with tools. The correction method is as follows: Remove the protective cover from the lens, cut a 0.5 cm wide strip of film, place about 10 layers under the lens, and place the film strip along the magnets on both sides of the lens bracket. Adjust the lens position to the gap between the magnets using the same amount of film, then re-solder the four lens bracket solder points with a 25W soldering iron (the focus and tracking leads). After soldering, remove all film strips, and the lens is centered.
Example 5. Disc skipping (decompression card +5V power insufficient)
[Model] Sony LBK-N350 combo audio/VCD/DVD player (a 5-disc CD player with a VCD-08 type 1.0 decompression card).
[Fault Symptom] Disc skipping occurs, even with original discs. Sometimes, the count display is normal but there is no image or sound output. The same disc may play normally sometimes but fail to read other times.
[Analysis and Repair] Based on experience, the issue is often due to aging or insufficient power in the laser head, dirty lenses, or servo circuit problems. However, the actual check reveals insufficient power supply to the decompression card (+5V, derived from the original machine's +12V via a 7805 voltage regulator). Monitoring the +12V and +5V power supplies shows they are stable, and the 7805 heatsink is normal. Nevertheless, an independent power supply is added to the decompression card. Two 7805s are paralleled with an enlarged heatsink, and the desired effect is immediately achieved.
Example 6. Unable to eject disc (IC603 internal damage)
[Model] Sony MDPK1 VCD/DVD player.
[Fault Symptom] Pressing the eject/insert button fails to eject the disc tray. Normally, the tray moves slowly during manual operation, and it moves even slower when a disc is inserted.