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Maintenance
Note
that
component
layout
drawings
are
Ux^ated
at
the
end
These
three
tests
can
also
be performed from
the front
panel
of Section
8.
Also,
refer to
Section
6
for
an overview of
oper-
through a
menu
selection
(SELF TEST)
or over the
ating principles.
IEEE-488
bus with
the
command
JO (Perform
Self-test).
7.9.1
Recommended
test
equipment
Success
in
troubleshooting
equipment
like
the
Model 707A
depends
not only
on
the
skill
of
the technician,
but also
on
the
use of
accurate,
reliable
test
equipment. Table 7-3
lists
the
minimum
recommended
equipment
for
troubleshooting.
Other equipment,
such
as logic analyzers,
could
also
be
helpful.
Table 7-3
Recommended
troubleshooting
equipment
Description
Application
DMM
(Keithley 2000)
Dual-
trace,
triggered
sweep
oscilloscope,
dc
to
50MHz
Measure
dc
voltage.
Check
clock
and
logic
pulses.
7.9.2
Power-up
self-test
As
described
in
Section
4,
the
Model
707A
performs a
series
of
tests
on
power-up.
Individual
tests
in
this
series that
can be
used
for troubleshooting a
Model
707
A
include:
•
ROM
test
-
A
checksum
test
of
ROM.
Test
failure
is
in-
dicated
by
a
ROM
FAIL
error
message.
•
RAM
test
-
A
read/write
test
of
battery
backed- up
CMOS
RAM.
Test
failure
is
indicated
by
a
RAM
FAIL
error
message.
•
Display
test
-
A
visual
test
of
the front
panel
displays.
•
Check
for
all
LEDs
and
indicators
being
lit.
7.9.3
Power
supply checks
Power
supply
voltages
should be checked
first
to
make
sure
they are within the required
limits. If
the
various operating
voltages are not within the
limits,
troubleshooting
the re-
maining
circuitry
can be
quite
difficult.
Table 7-4
outlines the
voltages
that
should
be
checked.
In
addition
to
the
usual
checks
with
a voltmeter,
it
is
a
good
idea
to
check
the supplies
with an
oscilloscope
to
make
sure
that
no
noise or ringing
is
present.
7.9.4
Digital
board checks
Tables 7-5 through 7-8
list
the
procedures
to
check
circuitry
on
the
digital
board, including
the
microcomputer,
relay
con-
trol
circuitry,
display
interface,
and
digital
I/O
port.
Procedures
for testing the light
pen and
master/slave
inter-
face options
are
listed in
Tables 7-9
and
7-10.
The
waveforms
described
in
the
troubleshooting
tables
are
present
with
power-up
default conditions
(idle
state),
unless
otherwise
indicated.
To
view
some
of
the
waveforms,
it
will
be
helpful
to
run
a
program
loop.
Refer
to
the
programs
of
Figure 7-10
when
directed
by
the
procedure.
NOTE
If
the
ROM
(U7)
must
be
replaced
for
any
reason, restore the
Model
101
to
factory
default
conditions with a
menu
selection
(FACTORY
INIT)
or
the
device-depen-
dent
command
RO.
Table 7-4
Power
supply checks
Step
Item/component
Signal
Comments
1
2
PSl
Voltage Regulator
PCB
6.2
VDC
±2%
(0.12V)
5VDC±1%
(0.05
V)
Measure
relay
coil
voltage
at
power
supply.
Measure
logic
voltage
and
front
panel display voltage
at
voltage regulator
board
TP
1
03
referenced
to
TPIOI.
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