Communications
Path
IMPORTANT!
When
using
the
Communication
Test
Board,
keep
in
mind that it is sensitive
to
static discharge.
Handle
the
board
by
the
edges
and store it
in
the
anti-static shipping
bag
when
not in use.
Do
not
let
the
board shan
out
when
testing,
place
an
insulator
(cardboard,
paper,
etc.)
underneath it.
Attaching the Communications Test
Board
If
an
EPS-16
PLUS has a communications problem,
turn
the unit
off
and unplug the 20-pin
Keyboard assembly ribbon cable from the Main Board at
-connector 112. Plug the
20-pin
ribbon
cable
from
the Communication Test Board into 112. This will eliminate the Keyboard assembly as a
variable.
Turn
the system on.
If
the communications problem persists, you know
the
Keyboard
assembly
is
not at fault
If
communication is restarted, however, the Keyboard assembly is at fault.
See the
flow
charts on pp. 12-15 for troubleshooting procedures.
There is
one
funher complication. Since the communications
path
between the Keyboard assembly
and Keypad/Display Board is routed through the Main Board, there is a remote possibility
that the
printed circuit connections between the two connectors
are
defective.
If
you have
an
EPS-16
PLUS
that has a problem communicating with its KeypadlDisplay Board, you may want to
verify
continuity
between
the
connectors on the Main
Board
Turn
off
the
power
and
unplug the 2O-pin ribbon cable
from the
EPS-16
PLUS Main Board
at
112
and
the
EPS-16
PLUS
7-pin Display
cable
from the
Main
Board
atJl5.
Using an Ohmmeter, verify continuity between the following points
on
the Main
Board:
20-pin Keyboard Connector
Pin
1
Pin
3
PinS
page 6
7 -pin DisPlay Connector
to
Pin
1
to
Pin
2
to
Pin
3
EPS-J6 PLUS Service Manual
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