14
Digitron is lit but
key do
not operate.
Is each key pulse
applied to pin ,
and of IC701?
2
3
12
13
Check key matrix
circuit.
Check the pin serial of
pin , ~ of IC701.
65 67
69
It has not power-failure
compensation
operation.
When disconnecting
the power cord,is 3.6V
at pin and
of IC601?
26
81
Do pin and
of IC601
oscillate?
42
Is +5V applied to
pin of IC601?
37
Check IC601.
Check C629.
Check X602
environmental circuit.
NO
YES
YES
YES
YES
NO
NO
NO
B.
C.
43
Check the IC606
RESET circuit.