Yamaha F-20B Service Manual - Page 8
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Also for Yamaha F-20B: Owner's Manual (7 pages), Installation Manual (12 pages)
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F-20B
IC BLOCK DIAGRAM
BA4558 (XO078A00)
Dual Operational Amplifier
Output A
1
Inverting
2
Input A
-
+
Non-Inverting
3
+
-
Input A
-DC Voltage Supply
4
-V
INSPECTIONS
1.
Preparation
To inspect the main unit, the following jigs are
required.
CD player
Headphones
Before turning the power on, set all the knobs on
the panel to "0".
Raise the Input Level Select Switch to select
[PASSIVE] position.
2.
Power supply
Connect the power cord to the suitable power
supply socket for each version.
(UC-120V, E&BS-220V)
3.
Inspection procedure
3-1
Input the audio signal of CD player to the [AUX IN]
jack.
3-2
Make sure that rotating the [VOLUME] knob to the
right (or left) makes the sound gradually larger (or
smaller).
3-3
Make sure that rotating the [TREBLE] knob to the
right (or left) boosts (or cuts) the high frequency.
3-4
Make sure that rotating the [HIGH MID] knob to
the right (or left) boosts (or cuts) the upper-middle
frequency.
3-5
Make sure that rotating the [LOW MID] knob to
the right (or left) boosts (or cuts) the lower-middle
frequency.
3-6
Make sure that rotating the [BASS] knob to the
right (or left) boosts (or cuts) the low frequency.
3-7
Make sure that the sound becomes smaller when
you depress the Input Level Select Switch to select
[ACTIVE] position.
3-8
Raise the Input Level Select Switch again to select
[PASSIVE] position. Make sure that the audio
signal sounds over the speaker.
3-9
Connect the headphones to the [PHONES] jack.
Make sure that the speaker produces no sound and
the audio signal sounds over the headphones.
3-10 Set all the knobs on the panel to "0" and finish the
inspection.
8
MAIN: IC1,IC2,IC3
+DC Voltage
+V
8
Supply
7
Output B
Inverting
6
Input B
Non-Inverting
5
Input B