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3. Coin screw insulation sheet attachment
.
!
A-A" cross section
:i:
The cushion must be attached
securely.
After the cushion glue is
dried, it cannot be reattached.
This part must be attached.
NG
OK
This section
must
be pasted firmly
Cushion
Upper cabinet
2. Battery holder cushion attachment
Battery
spacer
1----
1. Cabinet upper unit
0
Battery spacer attachment
8. Note for servicing
-
PC-:£220
>
~ -~AUlevel
~ - ----~STOP
>
level
~
~
t
Symbol
[Fig.
31
lights up.
0"""-~..1-~-"---'-~~-'---•
Voltage detection IC operation
[Fig. 2]
c
(V)TIN
VoMt--
VDL
r
(Fig.
11
GND
LB
-----1
CPU
CPU CAu---
(N-chopen)
R2
R1
Vee
r.
.
,.I
This unit is equipped with the low battery detection circuit. Its opera-
tions are described below. (The parts location numbers are different
from the actual ones.)
As shown below, when the input voltage VIN exceeds detection volt-
age VO, the output becomes HIGH from LOW. When VIN falls below
DIN, the output becomes LOW.
The LSIC (MN1280) detects the CAU level and the STOP level with
one
IC.
To achieve this, the input voltage applied to the input pin (2 pin) is
divided with R1 and R2, and R2 is turned on/off by the CAU signal.
As shown in Fig. 3, when the power voltage falls below the CAU level,
the BATT symbol lights
up.
When it falls further below the STOP
level,
it is turned
off.
To detect the CAU level, the CPU CAU pin is turned on (at low level)
and the LB pin of the CPU is checked. (If the LBC pin is
low,
the
symbol lights up.)
After detecting the CAU level, the CAU pin is turned off
(at
HIGH.)
(When the CAU pin is turned off, the resistor division is not performed
and the potential at SIC 2 pin rises to drive the output to HIGH.) Then
the CPU LS pin is checked again to detect the STOP level.
After
detecting the STOP level, the ON/BAK key and the RESET
switch do not work.
7. Low battery detection circuit
":':
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C
:'
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