About Tempo click, I hope this is of some help.
On PSR 740 the Tempo button is also the Tap tempo button.
So, the first time we click this button PSR 740 expect we are using
the Tap function. The Tap has a click sound as a metronome. That the reason
we hear a metronome click. But this only happen if the Auto accompaniment
is not playing. With this Part playing, we can also change the Tempo using the
Tap feature (in this case only two clicks are enough), or using the dial, or the number keys, without hear any metronome click.