Yamaha A-460 User manual

.ADJUSTMENTS
1. Idling current
You will find that Adjustment will be facilitated if you
When repairing the main amplifier (replacing TR105 to use the lead wires as shown in the bottom figure.
122), adjust idling current.
Connect to the •
a. Set the VOLUME control to its lowest position.
Connect to test points Vinyl wires colored voltage tester
~ white and red
b.
Rotate VR109 (Lch) and VR110 (Rch) for idling \ \
~
current adjustment fully counterclockwise.
c. Connect a voltage tester to the test points.
~c"p (Red. Black) Plug (Red. ~
(L ch: TP1 EEl '"" TP2 8 , R ch: TP3 EB '"" TP4 8 )
d. After the power has been switched, rotate VR1 09
and VR 110 and set so that the voltage between test
points comes to 15mV.
e. Set so that the voltage between test points comes
within 15 ± 3mV about 3 or 4 minutes after the
power has been switched on to enable the operation
of the amplifier to stabilize.
* When idling current rises abnormally and the voltage
of test points is very high, in spite of rotating VR109
or VR110 counterclockwise, the set is broken.
i~
[idling current adjustment (R eh] I
\ Iidling current adjustment (L ch] I
'1" I TP4
~_·-v
1 VRll0(R) VR109(LlcoTPl
:/
TP3 ~ @ o
TP2
I
Voltage tester
MAIN CIRCUIT BOARD [~l
,e
r
•
Adjustment
item
Channel Test point
Adjust·
ment VR
Rating or
standard
Idling current
L ch
TP1Ef! - TP28
VR109
l5±3mV
adjustment R ch TP3Efi ~ TP48
VRll0
•
,.
'J
•
•
,,
. '~".
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