Sharp PG-C20XU Service Manual page 33

Checking the
microcomputer
peripherals
Is a voltage of about 3V
applied to pin (33) (RCS)
of IC1601?
YES
Is SW1602 set at
"NORMAL" position?
YES
Is there pulse signal at
pin (64) of IC1601?
YES
Is there pulse signal at pin
(1) of IC1601?
YES
Is there signal at pins (1),
(3), (4) and (6) of IC1802?
YES
End
NO
Check the intake filter
cover for poor fitting and
the cooling fan for trouble.
NO
Set SW1602 to
"NORMAL" position.
NO
Check IC1601, IC1606 and
their peripheral circuits.
NO
Is the signal level at pin
(7) of IC8037 about 0V?
Check all the signals (A1
thru A17 and D1 thru D15)
of IC8021 with oscilloscope.
Are signal levels 0V and
3V?
End
NO
Check all the ICs
connected with the
SDA3/SCL3 and
SDA5/SCL5 lines.
33
NO
YES
Check IC8018, IC8019,
IC8020 and their peripheral
circuits as well pin (26) of
IC1601 and its peripheral
circuits.
NO
Check IC8021 and
IC8022. Replace the PC
YES
interface as required.
PG-C20XU
PG-C20XE
AN-Z7T