Troubleshooting; Ic And Transistor Lead Identification - Casio ML-1 Service Manual

TROUBLESHOOTING

Nature of Trouble Faulty Block
No power Power Supply Circuit
Power switch
Power Jack (J1)
No sound at all Power Amp.
(IC1: AN8053N)
CPU (LSI1: MSM6521-10)
Oscillator (XL1)
Keyboard LEDs don't Keyboard LED
light up
Keyboard LED Matrix
A certain key or switch Key and Switch Matrix
does not function
Certain keys or switches Key and Switch Matrix
do not function
Checkpoint
Base of T1 should receive +6 V.
Emitter of T1 should provide +5.6 V.
Switch contact.
Jack contact.
Pin 16 should receive +7.5 V when the
power switch is turned on.
Voltage at pin 14 should drop at 0V
when the power switch is turned on.
Check output signal of pin 1.
Voltage at pin 27 should rise 0V to 5.6V
when the power switch is turned on.
Pins 39 ~ 41 and 43 ~ 46 should provide
pulses.
Pin 29 should have a sound signal when
a key is pressed.
Pins 20 and 21 of the CPU should
receive an ocsillation signal.
Open circuir on LX or LY line.
Dust on the contact.
Open circuit on KC or KI line.
47
KO8
48
KO9
49
KO10
50
KO11
51
D4
52
D3
53
D2
54
D1
55
OP
56
Ø2
57
Ø1
58
CE
59
GND1
60
LY0
T1: 2SD1858Q, R
— 5 —
IC LEAD IDENTIFICATION
LSI1: MSM6521-10
30
AGND
29
OUT
28
AVDD
27
RESET
26
TEST3
25
TEST2
24
TEST1
23
GND1
22
VDD
21
COSO
20
COSI
29
GND2
28
LVDD2
17
LX7
IC1: AN8053N
T2: 2SC1740SQ