Battery Circuit - Olivetti ECR 7100 Service Manual

__________________________________________________________________________________________

4-12 BATTERY CIRCUIT

When the +18V supply starts dropping, as in a power fail condition, the voltage through the divider
network drops accordingly.
When +18V no voltage, Q3 and D8 are shut off current VBB is through the D9 from battery.
When the voltage at +18V has dropped, voltage back-up is provided by the battery.
The battery voltage VBB goes to the CPU and external RAM
Battery specification
Type : SUM-3×3pcs
Voltage : 1.5V x 3 = 4.5V
VCC
D7
1N4148
Q2
C E
2SC3242
R22
3.3K
EC3
+
C9
ZD1 10uF_16V
HZ6C3TA-E
0.1uF
_____________________________________________________________________________
Y110910 – 8
EC4
+
10uF_16V
D8
A K
1N4148
R27
4.7K
ZD2
HZ5B1
R26
B
Q3
2SC1815
100
R23
C2
0.01uF
330
ECR7100 Service Manual
.
PF
VBB
D9
K A
1N4148
+ EC5
10uF_16V
D20
JUMPER
CN2
2
1 BACK UP(1.5Vx3pcs)
B2B-XH-A
55