PacComm TINY-2 - Page 140

TROUBLESHOOTING
Computer
Terminal
interlace
Digital
loopback
Move
the
JP
L
jumper
to
‘LOOP’
and
attempt
to
pass
UI
frames
or
connect.
Digital
loopback
is
very
reliable
and
should
work
every
time
if
there
is
no
problem
in
the
digitat
portion
of
the
board.
General
Tests
The
TINY-2/MICRO-2
has
status
LEDs
which
are
powerful
tools
in
troubleshooting.
Many
suspected
problems
may
be
disproved
by
the
following
simple
tests.
Connect
a
power
source
to
the
TINY-2/MiGRO-
2
and
a
voltmeter
(15
volt
scale)
to
pin
2
of
the
RS-232
connector.
Do
not
connect
any
computer
or
radio
cables.
Turn
onthe
TINY-2/MICRO-
2.
Observe
the
LEDs.
Ifthe
TINY-2/MICRO-2
powers
up
with
the
PWR,
CON
and
STALEDs
lit,
followed
by
the
CON
and
STALEDs
extinguish-
ing
a
second
or
so
later,
and
the
voltmeter
shows
a
lot
of
activity
for
about
1\2
second,
the
TINY-2/MICRO-2
digtal
section
is
operating
and
attempting
to
send
a
sign
on
message
out
the
Serial
port.
Step
1:
Obvious
Problems
Look
for
any
unusual!
physical
symptoms.
Is
the
unit
drawing
excessive
current
?
Are
any
components
discolored?
Does
something
smell
burnt?
Do
any
of
the
parts
seems
excessively
warm?
In
general,
their
normal
temperature
(NMOS)
will
be
quite
warm
to
the
touch.
CMOS
parts
should
not
show
any
heating.
Step
2:
Power
Supply
The
first
thing
to
check
in
any
malfunction
is
the
power
supply.
:NOTE:
A
frequent
problem
is
the
use
of
a
poorly
fittered
or!
iundervoltage
DC
power
supply.
:
Check
that
the
voltage
under
load
is
not
low
and
that
excessive
ripple
is
not
present.
Check
the
power
supply
levels
at
the
output
of
the
voltage
regulator.
Do
all
the
ICs
in
the
suspected
area
have
the
proper
voltage
on
their
power
pins?
ts
there
excessive
ripple
in
any
of
the
bc
voltage
lines?
If
so,
check
the
regulator
and
associated
components,
working
backwards
toward
the
input
power
switch.
If
the
voltage
is
low,
in
conjunction
with
a
hot
regulator,
suspect
a
short
circuit
on
the
board.
Computer
Terminal
Interface
If
you
can't
get
the
packet
controller
to
sign
on
and
accept
data
trom
the
terminal
or
computer,
the
problem
may
be
in
the
serial
interface.
iN
OTE:
The
primary
cause
of
non-communication
between
th
ipacket
controfler
and
the
computer
is
improper
cabling
setup.
Inspect
the
interconnection
cabling.
Does
it
work
on
another
controller
or
RS-232
device?
Has
the
radio
and/or
computer
been
successfully
used
on
packet
with
this
or
another
packet
controller?
Are
ail
the
connections
tight?
Has
the
cable
frayed
or
broken?
oe
TINY-2/MICRO-2
Technical
Ref.,.2
Ed
©
1989,
PacComm,
Inc.
19