Bally 5000 Plus, Manual

Page: 115 / 388

3 . MPU BOARD
C i r cu i t Descr i pt i on ( cont ' d )
Ba t t e r y
The b a t t e r y supp l i es powe r t o t he
door l a t c h , S a f e RAM , and r e a l t i me
c l ock c i r cu i t s when t he mach i ne I s
w i t hout powe r .
Cha r g i ng
The + 1 2 V c h a r ge s t he 3 . 6 V
ba t t e r y when J 1 6 i s I ns t a l l ed b y
us i ng t he R 1 0 , CR4 ,
CRS a n d R 1 1
pa t h . C R 4 c l amps t he + 1 2 V t o
S . 7 V .
The CRS b l ock i ng d i ode c l amps t he
vo l t a ge
t o S V a n d p r even t s
r e ve r se l ea k age i n t o t he + 1 2 V
c i r cu i t .
R 1 0 and R 1 1 l i m i t t he c h a r g i ng
cur r e n t t o 1 0 m a o
Powe r down
W i t h J 1 6 i ns t a l l e d , t he b a t t e r y
vo l t age ( VBB ) i s d i s t r i bu t e d t o
t he ba t t e r y backed c i r cu i t r y
t h r ough R 1 1 .
De t ec t
U70 d e t ec t s
d i s c h a r ged
b r ea k down ) . i f t he ba t t e r y i s
o r s ho r t e d ( i n t e r n a l
R l and CR2 set up
a 3
.
0 V
r e f e r ence vo I t a ge a t U70 p i n 6 .
T h e 3 . 6 V ba t t e r y vo I t age i s
mon i t o r e d a t U70 p i n
S .
When t he
ba t t e r y vo l t age t a l I s be l ow
3
.
0
V , U70 p i n 7 sends a VSS
BAD
s i gna l t o U45 p i n 2 .
3-S8
NOT E S