故障现象:VH频段只能收看低端电视节目,且有跑台现象,VL和U频段均收不到台。分析检修:就单纯的某频段收不到台而言,只能是波段控制电路或高频调谐器本身故障。但从本例的故障现象来看,似乎是调谐器内部的振荡频率发生了偏移,使频率覆盖范围偏向了一边,而且还不稳定。由此分析,调谐器电压的不正确和其本身的不良,将是导致该故障的直接因素。 Symptoms: VH band can only watch low-end television programs, and there are treadmill, VL and U band are not received Taiwan. Analysis and maintenance: a simple band can not receive a band, only the band control circuit or high-frequency tuner itself fault. However, from the failure phenomenon of this example, it seems that the internal oscillation frequency of the tuner has been offset, which makes the frequency coverage deviate from one side and is not stable yet. From this analysis, the tuner voltage is not correct and its own poor, will be the direct cause of the failure.