MICROPROCESSOR TEST PROGRAM
The
test
programming is stored in the microprocessor
of
this unit. Judge troubles according to the following procedure
when the microprocessor
and
peripheral circuits are malfunctioning.
IC401
Set
the
power switch
to
OFF,
insert a diode
between pin
@
of
IC401
and
GND, then set the
auto/memory rewind switch
to
PLAY.
Set
the
power switch
to
ON. The test program is
executed.
Is
the
PAUSE indicator lit for approx. 600ms
NO
Set
the power switch
to
OFF
and connect pins
every time the tape select switch is changed over?
®
and
@l
of
IC401
directly
to
GND, then set
the power switch
to
ON.
YES
YES
Is the PAUSE indicator
lit
for approx. 600ms
Test program execution instruction
every time the tape
select switch is changed over?
input circuit faulty.
NO
YES
Is the PAUSE indicator
lit
when
pin®
or
@of
Tape select circuit faulty.
IC401
is directly connected
to
GND?
NO
•
Check the
pin
®
output
and
the LED drive
circuit.
ls
the
PLAY indicator lit
and
1
kHz
test signal
obtained
when
the PLAY button is pressed after
the
cassette tape is loaded?
YES
NO
Connect the input pins
of
IC401
corresponding
Is
the
PAUSE indicator lit for approx.
600ms
NO
to respective input buttons directly to
GND
and
when the
PAUSE button is pressed?
check the
output
at that time.
In addition, check
NO
the circuit
of
that output.
YES
Is
the
REC
indicator lit
and
12
kHz
test signal
obtained
when
the
REC
button is pressed?
YES
Test program completed. Remove the diode
connected between pin
@and
GND.
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26-
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