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例1.故障现象:开机播放时声音正常,但局部图像始终有马赛克现象。分析与检修:该机采用最新MPEG2解码芯片CL8820。主控CPU通过控制器将ROM中的数码信号、OSD数据及开机画面等数据,调入DRAM及解码芯片U3(CL8820),在CPU控制下,U3对机芯送来的数据信号进行解码等操作,输出音/视频数码信号,再经D/A转换后输出模拟音/视频信号。该机声音正常,说明解码电路工作正常。而局部图像有马赛克出现,估计为解码缓冲区异常,应重点检查DRAM U5～U9。检查发现U6温升明显高于其它集成块,故而判断U6不良,试将其更换后,播放碟片试机,图像中的马
Example 1. Symptom: The sound is normal during boot playback, but the local image always has a mosaic phenomenon. Analysis and Maintenance: This machine uses the latest MPEG2 decoder chip CL8820. The main control CPU transfers the digital signals, OSD data and boot screen data in the ROM into the DRAM and the decoding chip U3 (CL8820) through the controller. Under the control of the CPU, the U3 decodes the data signals sent by the movement , Output audio / video digital signal, and then output analog audio / video signal after D / A conversion. The machine sound is normal, indicating that the decoding circuit is working properly. The local image mosaic appears, it is estimated that the decoding buffer is abnormal, should focus on checking DRAM U5 ~ U9. Inspection found that U6 temperature rise was significantly higher than other manifolds, so to determine the U6 is bad, try to replace it, play the disc test machine, the image of the horse