Yamaha MU128, Service Manual

MU128

22

Distortion factor 0.25 % or less
When A/D INPUT VOLUME is set at minimum, make
sure that the specified value shown below is obtained
for OUTPUT (R).
OUTPUT (R) : -72 dBm or less

Set A/D INPUT VOLUME at maximum. When the
inputting the sine wave data -9.0 dBm and 1 kHz in
the AD INPUT (L) field, make sure that all the level
meter lamps on the LCD are lit.

Ending the test
Press the [ENTER] button. You will then go to the
next test.

18.

DSP AND DRAM

18  DSP  &  DRAM

Measure the frequency, waveform and level of

individual signals output from the OUTPUT (L, R)
terminals and make sure that the 

proper

 signals are

being input. Before starting the measurement, make
sure that the plug is not inserted into the AD/ INPUT
terminal. Also set the master volume at maximum.
Observe the situation for at least two seconds.

Check items
OUTPUT (L) : 1 kHz +/- 3.0 Hz, Sine wave,

+3.5 dBm +/- 2 dB (Load: 10 k ohm)
Distortion factor 0.25 % or less

OUTPUT (R): 1 kHz +/- 3.0 Hz, Sine wave,

+3.5 dBm +/- 2 dB (Load: 10 k ohm)
Distortion factor 0.25 % or less

Ending the test
Press the [ENTER] button. You  will then go  to the
next test.

19.

CHECKING THE 128 SIGNAL SOUNDS

19  128ch  OUT

An audible 

signa

l is produced for channels 

1 to 64

 from

OUTPUT (L) and for channels 65 to 128 from OUTPUT
(R).

The audible signal is produced 64 times for approximate

0.3 seconds at intervals of approx. 0.1 second.
Make sure that the proper audible signal is heard for
each of the 128 channels. Also make sure that the
sine wave being output has the proper waveform.
(L ch = 1 kHz, R ch = 2 kHz)
Before starting the  test, set the master volume at
maximum at the time. During the test, the following
information will appear on the LCD:

19  128ch  OUT
Lch=xx    Rch=xx

(xx : Channel number with the audible signal

being produced.)

Ending the test
Press the [ENTER] button. You will then go to the
next test.

20. PB1 NAME

Note 1:

For test 20 to 23, connect the PB (plug-in board) to
the CN 5 of the DM sheet in the equipment before
turning ON the equipment.

20  PB1 NAME

A request for the board name and version is sent from
the MU to the PB 

through the

 MU-PB 

communications

signal line. The information obtained from the PB is
th en di splay ed on  the  LCD.  Ma ke s ure  that  the
communications signal line for the CN 5 of the DM
sheet 

is

 functioning properly 

and

 check the board

name and version.

Displaying the test result
OK

20  PB1 NAME
PLG100-(VL)     VX.XX

(X.XX = Version number)

NG

20  PB1 NAME
                                    err

(If no information is returned from the PB.)

21. PB1 RAM

21  PB1 RAM

Check the RAM of the PB connected to the CN 5 of
the DM sheet.

Displaying the test result
OK

21  PB1 RAM
                                ok

NG

21  PB1 RAM
                                err

22. PB1 MIDI IN

22  PB1 MIDI IN

Check the MIDI IN of the PB connected to the CN 5 of
the DM sheet.

Use a MIDI cable and connect the MIDI IN A (Rear)
connector to the MIDI OUT connector. Then conduct
the test.
Before starting the test, select MIDI under HOST SELECT.

Displaying the test result
OK

22  PB1 MIDI IN
                                ok