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[故障现象]机内有“啪啪”放电声;画面大块色斑;声音小且失真;自动搜索中不能自动锁台。[检修]开盖检查,发现高压帽与后盖上面有打火痕迹,且高压帽已击穿(主要原因是高压帽与后盖的凸起处靠得过近)。用小钢锯将后盖凸起处削去一半,并将高压帽换新后,打火故障排除。屏幕上出现色斑,一般是围消磁电阻变值或开路所致。经测量消磁电阻阻值已增大至100Ω(正常应为27Ω),将其更换后色斑消失,接下来排除声音小,且失真的故障。用感应法从IC101(TA7680)第脚加入感应信号,扬声器有很大的交流声,表明故障可能在伴音中放及鉴频电路。根据检修经验,多为鉴频中周失谐,使其谐振点偏离6.5MHz所致。试调整中周T102的磁芯后,声音恢复正常。
[Symptoms] machine has “pops” discharge sound; large chunks of images; sound small and distorted; automatic search can not lock the stage automatically. [Overhaul] Inspection of the open lid revealed that there was a fire mark on the high pressure cap and the back cover, and the high pressure cap had been punctured (mainly due to the bulge of the high pressure cap and the back cover being too close). Use a small saw to cover the raised half of the cover, and the pressure cap after the new, sparking troubleshooting. Color spots appear on the screen, usually around the degaussing resistance variable value or open due. Demagnetization resistance has been measured by the resistance has increased to 100Ω (normal should be 27Ω), the stain will disappear after its replacement, then rule out the sound is small, and the distortion of the fault. Sensing method from the IC101 (TA7680) the first foot of the induction signal, the speaker has a great hum, indicating that the fault may be placed in the audio and frequency circuit. According to the maintenance experience, mostly in the frequency of the week detune, so that the resonance point deviation from 6.5MHz caused. After trying to adjust the core of the week T102, the sound returned to normal.