Realistic PRO-2021 - Memory Check

POWER ON
Enter (program)
150,000 in CH1
Power switch OFF
Does
5+0.3V exist
at Pin 33 of
ІС11?
YES
Power switch ON
Is 150,000
displayed at
CH1?
YES
Disconnect AC or DC
plug and then connect
after 2 hours.
Power switch ON
Is 150,000
displayed at
CH1?
YES
MEMORY circuit is OK
NO
NO
NO
MEMORY CHECK
NOTE 1:
NOTE 2:
Defective Voltage
Regulator IC 10.
Defective CPU control
circuit, 018 ~ 019
and/or IC 12
Defective Back-up
battery.
Prior to checking CPU System, measure
supply
voltage
to
ICs.
(See
schematic
drawing.)
While checking the following items, the
ICs can "latch up”. If so push RESET
switch about one second and then
continue.
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