PURPOSE:To surely prepare AFT-H signals and AFT-L signals by phohibiting the checking of horizontal synchronization detection signals in AFT-L side at the time of high speed sweeping of a first tuning voltage in the case of executing a receiving judgement to a down tuning. CONSTITUTION:When a tuning up key is operated, a tuning position is forcibly 32 stepped down, and stepped down at high speed to show a tuning voltage counter 29 by a timing signal phiM until tuning voltage comes near the next channel. An SFT-L signal is sent from a comparator 45 to a flip-flop 59 independently of a horizontal synchronization detection signal SI. After passing through an optimum tuning position once, an AFT-H signal is outputted from a comparator 44, the tuning voltage counter 29 is stepped back. Thus, AFT-L signals can be detected surely even when the deviation is caused between the horizontal synchronization detection signal SI and AFT signals at the time of channel down.
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