Yamaha SPX990 Service Manual page 22

SPX990
SPX990
(1)
When
the data has
been
read
correctly,
the
TEST
15.
AD
CIRCUIT
BOARD CHECK
following display
appears
This test
is
utilized
by
the factory and
it is
not
intented
for
field
service use
DIAG.
VTO
TEST
TRGO OK
(2)
When
the data has
not
been
read, the following
display appears.
DIAG
V1.0
TEST
TRGO
NG
TEST
14.
D-RAM CHECK
Discovers defective areas
of the
DSP D-RAM,
and
reports the defective
bits
(1)
The
following display appears on
the LCD,
DIAG- VI
.0
TEST D-RAM
(2)
When D-RAM
Is
normal, the following
display
appears on
the
LCD.
DIAG, VI
0
TEST D-RAM
OK
(3)
When D-RAM
Is
defective, figures
which
correspond
to the
D0-D27
terminal nos. of
DSP2
(IC29)
appear on
the LCD.
Refer
to
the following
table to find the defective
1C.
Example
of display
when
defective:
DIAG. VI
0
TEST D-RAM
D12
Display
when
defective
and corresponding
IC
No.
table:
Display
Defective
iC
DOO
-
DOS
1C21
D04
-
D07
IC22
DOS -Dll
IC23
D12
-
D15
IC24
D16-D19
IC25
D20
-
D23
IC26
D24- D27
IC27
29