Casio SK-8A Troubleshooting guide

CONTENTS
1. SCHEMATIC DIAGRAM
1-1. Main PCB M3123-MA1M. 1
1-2. Console PCB M3123-CN1M . 2
1-3. LED PCB M3123-LD1M . 3
1-4. Keyboard PCB M3129-KY1M . 4
2. PCB VIEW & MAJOR CHECKPOINTS . 5
3. MAJOR WAVEFORMS. 6
4. BLOCK DIAGRAM. 7
5. KEY & SWITCH MATRIX. 8
6. CPU (MSM6283-05GS) . 9
7. PERCUSSION GENERATOR (MSM6294-02). 11
8. MELODY CIRCUIT.12
9. SAMPLING CIRCUIT.13
10. PERIPHERAL DEVICE ACCESS.14
11. ROM PACK ACCESS . 15
12. LED DRIVE CIRCUIT .16
13. RESET & POWER ON/OFF DETECTION CIRCUITS.17
14. POWER SUPPLY CIRCUIT .. .18
15. TROUBLESHOOTING ..19
PARTS LIST
SK-8.20
SK-8A .27

1. SCHEMATIC DIAGRAM
1-1. Main PCB M3123-MA1M
A I B
To LEDs
I ''
DC !N HEAD PHONE
TC4066BP13/A 1
VA
?
co kM cn p cn p- In
< o o o o olo o
] -J -J _l -I Jl -J J
■ f iTunf T- r nc ut ■
i n n ci ci col co co
I2SB12S6R
J2SCn4 0LNSR <gv
IOV220M T
Power
a.
Amp. 2 J
v 2 2
J V
C22I
138
10V47M |
Apo [50V2.2A
IK 10KB
_, MAIN VR
1 -"— " 5j—
t Mixing Amp.
5l)V1M
1 '* Tuft
2 )
1 100K
~68K
r
iwtlHIwj
y
TC40S6BP !3/4I
Go in Con t r o 11 er
12SC1740LNSR V0O_
>CV 15K 15K 15K

1 -2. Console PCB M3123-CN1M
A|B_j_C[0|E_j_F|G|H
A B C D E F G H

J_j_K|L|M|N_j_0|P
-2 -
i
2
j 3
L
5
6
7
8
9
10
I
! ii
i

I
i
wr

MAIM