Bally 5000 Plus, Manual

Page: 122 / 388

3 . MPU BOARD
T roub l es hoo t i ng ( cont ' d )
R E S E T FLOWCHART
n
-
'"
R E P L A C E U 39 ,
OR C H E C I< F O R
P R O P E R L O G I C
L E V E L S
GOOD
R E P L A C E
U 2 1
STA R T
R E S E T C I R C U I T
FAU LT I S O L A T I O N
G O O D
R E P L A C E
U 2 1
o r
U 4 2
NOTE
1 :
Log i c ( 1 ) H I GH w i th sw i tch not pushed
Log ic (0) LOW w i th sw i tch pushed
NOTE 2 : Log i c ( 1 ) w i th sw i tch pushed
Log i c (0) w i th sw i tch not
pushed
NOTE 3 : Log i c ( 1 ) w i th sw i tch pushed
Log i c (0) w i th sw i tch not pushed
CH E C K F O R
B A D SW I T C H , O R
O P E N T R A C E
TO U 3 9 , P I N 2
GOOD
R E P L A C E
U 2 1
GOOD
CHECK FOR
P R O P E R LO G I C
L E V E L S
I f pin 12 does not togg l e :
1 .
check
U42 pin
1
for l og i c ( 1 ) ; if not , check pu l I
up
reS i stor
2. check U42 p i n 2 for log iC ( 1 ) ; i f not , check watchdog
3-65