Yamaha YST-SW800 Service Manual page 7

Check the operation and make adjustment as follows.
a. Connect CB205.
b. Connect the probe of the oscilloscope between TP201
and TP202.
c. Turn on the power switch and the STANDBY/ON switch
on the front panel.
d. Check the waveform on the oscilloscope and adjust
VR201 so that a = b is obtained.
Permissible range: a/b = 1.0 ± 0.1
CAUTION
Electric potential is always applied to the ground side of the oscilloscope.
Be careful so that no other part comes in contact with it.
Caution for operation check of the SW power supply section and the power amplifier
As a high voltage is applied to the SW power supply section and the power amplifier, be careful not
to receive an electric shock.
Power (1) P.C.B
Main (1) P.C.B
– B
GND
+ B
Main (2) P.C.B
Q18 Q16 Q22 Q24 Q25 Q23 Q17
Q39
a
0V
b
H : 10 µsec/div
V : 50V/div
AC range 1 : 1 probe
q
Q19
YST-SW800
280Vp-p
6