Yamaha MU128, Service Manual

MU128

24

(Details)
The signal input into AD INPUT is output from the
CN4 -MEL  OUT of MU1 28 a nd a r equest  for th e
audible signal is made to the PB. The sound source
PB then outputs a 1 kHz sine wave from MEL OUT.
The effect PB (PLB-100VH) then outputs the input
signal from MEL OUT. The MU128 then outputs the
sine wave input into CN4-MEL IN from OUTPUT.

1. Testing the MU128

Make sure that the MEL IN/OUT of the CN4 is
functioning properly.

2. Testing the sound source PB 

(PLG100-VL, DX, etc.)

Make sure that the sound source section and the
MEL OUT are functioning properly.

3. Testing the effect PB (PLG100-VH)

Make sure that the effect section and the MEL
IN/OUT are functioning properly.

Insert the plugs into the OUTPUT (L, R) terminals and

measure the frequency, waveform and level of each

signal output. Set VOLUME and A/D INPUT VOLUME
at maximum.

Check items
When the sin wave data---1 kHz and -15dBm---are
input into A/D INPUT (L), make sure the following
specified values are obtained for OUTPUT (L).
OUTPUT (L):

1 kHz +/- 3 Hz, 4.0 dBm +/- 2 dBm (PLG100-VH),
1 kHz +/- 3 Hz, 3.2 dBm +/- 2 dBm (PLG100-VL),
1 kHz +/- 3 Hz, 2.0 dBm +/- 2 dBm (PLG100-VS),
1 kHz +/- 3 Hz, 0.8 dBm +/- 2 dBm 

(PLG100-XG)

Ending the test
Press the [ENTER] button. You will then go to the
next test.
When testing the MU128, use PLG100-VH.

Note 3: For tests 28 to 31, connect the PB to the CN1

before turning ON the equipment.

28. PB3 NAME

28  PB3 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 then displayed on the LCD. Make sure that the
communications signal line for the CN 1 of the DM
sheet is 

functioning

 properly and check the board

name and version.

Displaying the test result
OK

28  PB3 NAME
PLG100-VL
VX.XX

(X.XX = Version number)

NG

28  PB3 NAME
                                    err

(If no information is returned from the PB.)

29. PB3 RAM

29  PB3 RAM

Check the RAM of the PB connected to the CN 1 of
the DM sheet.

Displaying the test result
OK

29  PB3 RAM
                                ok

NG

29  PB3 RAM
                                err

30. PB3 MIDI IN

30  PB3 MIDI IN

Check the MIDI IN of the PB connected to the CN 1
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

30  PB3 MIDI IN
                                ok

NG

30  PB3 MIDI IN
                                err

31. PB3 MEL

31  PB3 MEL

Perform the tests 1 to 3 described next and make
su re that  th e prope r sig nal is bei ng out put from
OUTPUT (L, R).
(Details)
The signal input into A/D INPUT is output from the
CN1-MEL OUT of MU128 and a request for the audible
signal is made to the PB.
The sound source PB then outputs a 1 kHz sine wave
from MEL OUT. The effect PB (PLG-100VH) then
outputs the input signal from MEL OUT.
The MU 128 then outputs the sine wave input into
CN1-MEL IN from OUTPUT.

1. Testing the MU128

Make s ure that  the MEL IN/OUT of  the  CN1  is
functioning properly.