Ic Block Diagram - Yamaha F-20 Service Manual

F-20

IC BLOCK DIAGRAM

BA4558 (XO078A00)
Dual Operational Amplifier
Output A 1 +V
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 CH SELECT switch to select channel A.
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 the sound becomes gradually larger (or smaller) according as you turn the VOLUME knob to the
right (or left).
3-3 Make sure that the high frequency is gradually emphasized (or eliminated) as you turn the TREBLE knob to the
right (or left).
3-4 Make sure that the middle frequency is gradually emphasized (or eliminated) as you turn the MIDDLE knob to
the right (or left).
3-5 Make sure that the low frequency is gradually emphasized (or eliminated) as you turn the BASS knob to the right
(or left).
3-6 Make sure that the sound becomes larger when you depress the CH SELECT switch to select channel B.
Besides, make sure that the sound becomes gradually distorted according as you turn the GAIN knob to the right.
3-7 Make sure that the sound becomes gradually larger (or smaller) according as you turn the MASTER VOLUME
knob to the right (or left).
3-8 Raise the CH SELECT switch to select channel A and make sure that the audio signal sounds over the speaker.
3-9 Connect headphones to the PHONES jack. Make sure that the speaker does not produce any sound and audio
signal sounds over the headphones.
3-10 Set all the knobs on the panel to "0" and finish the inspection.
8
MAIN: IC2,IC3
+DC Voltage
8
Supply
7 Output B
Inverting
6
Input B
Non-Inverting
5
Input B