Yamaha ACU16-C Service Manual page 37

5. Testing of DAC circuit board
5.1 Connection
Set SW201 of the MAIN circuit board to "0".
Using the USB cable, connect CN308 of the MAIN circuit board and the USB terminal of PC.
Using the serial cable (cross), connect CN602 of the DAC-JACK circuit board and the serial terminal of PC.
5.2 Testing method
Select "7. ACU16-C DAC SHEET" on the start-up screen of the TEST program, and testing of following test items is executed
when the "ENTER" key of the keyboard is pressed.
1 LED : LED lighting test
Check that LED's on the DAC-LED circuit board light up in the order of [LD801] → [LD803] → [LD804] and then all
three of them simultaneously.
2 DAC : D/A converter test
Check that the output level is +18dBu±1dBu at SP201, SP202, SP301 and SP302 of the DAC - DAC 1 circuit board.
Check that the output level is +18dBu±1dBu at SP401, SP402, SP501 and SP502 of the DAC - DAC 2 circuit board.
Check that the output T.H.D. is -80dB or less at SP201, SP202, SP301 and SP302 of the DAC - DAC 1 circuit board.
Check that the output T.H.D. is -80dB or less at SP401, SP402, SP501 and SP502 of the DAC - DAC 2 circuit board.
Press the "ENTER" key of the keyboard.
Check that the output level is -30dBu or less at SP201, SP202, SP301 and SP302 of the DAC - DAC 1 circuit board.
Check that the output level is -30dBu or less at SP401, SP402, SP501 and SP502 of the DAC - DAC 2 circuit board.
DAC-DAC 2 DAC-DAC 1
circuit board circuit board
to be tested to be tested
(V905060) (V905050)
CN501 CN401 CN301 CN201
CN603
CN604
CN308
MAIN sheet (V899900)
DAC LED circuit board to be
tested
Windows
PC
CN602
DAC-JACK
(V905070)
CN601
CM-1(V981120)
CN403 CN402
CN301
CN801
(V983590)
POWER
SUPPLY
(V970290)
CN51
ACU16-C
37