Yamaha BBT500H Service Manual page 35

5. Speaker output check
5 - 1.Connection
2 500W non-guide resistor is connected to speaker jack.
1KHz signal is put into an input jack.
Turn off a power supply switch.
5 - 2.Mesurement
Volumes are initial setting.
Set sound type to FLAT.
Power supply is switched on.
Turn OUTPUT volume to the right and check that 28.0V or more of outputs comes out.
It does not decide about T.H.D.
28.0V /2 =400W
BBT500H
35