31
Fault Finding
Check all links and jumpers, check no chips have bent legs and thus not making
contact with their socket, carefully inspect all soldering, check all the chips are
inserted the right way round, check all the components are in the right place.
With the PIO module plugged in to the RC2014 backplane with no other boards
fitted. Power the backplane and perform the following checks with a volt meter:
Check the supply voltage on the PIO module, between, say, U1 pin 10 and U1
pin 20. This should be 4.5 to 5.5 volts, preferably 4.75 to 5.25 volts.
Check the interrupt enable input (IEI) on connector P4 is being pulled up to at
least 4.5 volts.
Check each address switch input (Q2 to Q7) on U1 is being pulled up to at least
4.5 volts when the appropriate switch (SW1) is Off (open) and drops to less
than 0.4 volts when the appropriate switch (SW1) is On (closed).
