Yamaha YPT-370 Manual de serviço - Página 22

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PSR-E373/YPT-370
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DMLCD Circuit Board Check Method
The DMLCD Circuit Board has the test points for repair check purposes.
Check the test points on the DMLCD Circuit Board when the following problems happen.
Problems and Test points
▪ No display although turning on the power ⇒ Check the test points from No.1 to 6 sequentially.
▪ No sound or distorted sound --> Check the test points No.3, 5, 7 and 8.
NO.
Caution:
▪
Use the standard AC adaptor PA-130, PA-130B or PA-130U for check operation.
22
Test Point
Circuit
1
+B
Power supply voltage
2
+5D
5V power for digital circuit
3
+5A
5V power for analog circuit
4
+3.3D
3.3V power for digital circuit
5
+3.3A
3.3V power for analog circuit
6
/RESET
CPU & memory reset signal
7
DAC-L
DAC output L channel
8
DAC-R
DAC output R channel
6
1
3
5
Table
Point List
Judgment criteria
More than 11.0V
5.0V±0.5V
5.0V±0.5V
3.3V±0.3V
3.3V±0.3V
3.3V±0.3V
There shall be audio output
Signal Checker
without distortion.
There shall be audio output
Signal Checker
without distortion.
DMLCD Circuit Board (VCX50800)
4
2
7
Measured by
Parts with possible defects
TR103 or FZ101
Multimeter
(On PNL Circuit Board)
Multimeter
IC801
Multimeter
IC801
Multimeter
IC802
Multimeter
IC802
Multimeter
IC101
IC201
IC201
8
Component Side