ZiLOG Z80

24
Step 10
Removeany solder ‘splats’ with a brush,such as an oldtoothbrush.
Visually inspect thesolderingfor dry joints andshorts.
Cleanthe flux off withsuitable cleaning materials.
Visually inspect again.
Beforefittingthe ICsor jumper shunts, plug the boardinto anRC2014 backplane
withno other boardsfitted. Powerthe backplane and performthe followingchecks
witha voltmeter:
 Check the supply voltage onthe PIOmodule,between, say, U1pin 10and U1
pin 20.This shouldbe 4.5 to5.5 volts, preferably 4.75to 5.25 volts.

Check
the
interrupt
enable
input
(IEI)
on
connector
P4
is
being
pulled
up
to
at
least 4.5 volts.
 Check eachaddressswitch input(Q2 toQ7)on U1 isbeing pulled up toat least
4.5 voltswhenthe appropriateswitch (SW1) isOff (open) anddropsto less
than 0.4 voltswhen the appropriateswitch (SW1) isOn (closed).
If all is well, powerdown andremovethe PIO module.