Casio SF-4300A Service Manual & Parts List page 17

Is 17-Pin of µPD3056G -007(LSI 1)
0[V]?
Is 18-Pin of µPD3056G-007 (LSI 1)
0[V]?
Y
Is 3-Pin of S-81250HG-RD (IC4) 5[V]?
Are capacitor C12, C13 OK?
Replace IC4
Refer to <No/Erratic display>
<No key input>
Does key make positive contact with
L571-1 Ass'y
Replace µPD 3056G-007 (LSI1)
1
Y
Y
N
Y
Y
—
15
N
Replace IC1
N
Replace TC4S69F (IC2)
N
Replace C12, C13
N
Clean/Adjust contact
—