Hitachi D-E99 Service Manual page 22

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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