ENSONIQ EPS 16 Plus Service Manual page 10

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