Pioneer SC-27 Service Manual page 36

1
Step 3: EXTAL Clock
A
S
24ON
X2501 (Pin 1)
No
Check the output of pin 4 of IC2601
Is the logic
(Port Expander) on the path.
gate "H"?
Yes
T
X2501 (Pin 3)
Does the
B
No
crystal oscillate
Replace X2501.
at 24.576 MHz
?
Yes
U
IC2502 (Pins 3,8) BUFFER
Is there
No
a clock output
Check the path, or replace IC2502.
(24.576 MHz)
?
Yes
V
C
IC2301 (Pin 80) 1stDSP EXTAL
Is there
No
a clock input
Check the path.
(24.576 MHz)
?
Yes
W
IC2401 (Pin 45) 2ndDSP EXTAL
Is there
No
a clock input
Check the path.
D
(24.576 MHz)
?
Yes
To Step 4
E
F
36
1
2
Step 4: Audio Signal
X
IC2301 (Pins 89,134) MCLK
Are there
MCLK inputs to
Y
IC2401 (Pin 73)
Is there a
MCLK input to
2nd DSP
Z
IC2301 (Pin 93)
Is there a
BCK input to
a
IC2301 (Pin 94)
Is there a
LRCK input to
b
IC2301 (Pin 97)
Is there a
DATA input to
To Step 5
SC-27
2
3
No
Check the signal path.
1st DSP
?
Yes
No
Check the signal path.
?
Yes
BCK
No
Check the signal path.
1st DSP
?
Yes
LRCK
No
Check the signal path.
1st DSP
?
Yes
DATA
No
Check the signal path.
1st DSP
?
Yes
3
4
4