Heathkit HD-1250 - In Case of Difficulty; Visual Tests; Precautions for Troubleshooting

Page
58
IN
CASE
OF
Begin
your search
for
any trouble
that
occurs
after
assembly
by
carefully
following
the
steps listed
below
in
the "Visual
Tests."
After
the "Visual
Tests"
are completed,
refer
to the
"Troubleshooting
Chart."
NOTE: Refer
to the
"Circuit
Board
X-Ray Views"
on Page
64 for
the
physical
location
of
parts
on the
circuit
board.
VISUAL
TESTS
1.
Recheck
the wiring.
Trace
each lead in
colored
pencil on
the Pictorial
as
you check
it. It is
frequently
helpful
to have
a
friend
check
your
work.
Someone
who
is not
familiar
with the
unit
may notice
something
consistently
overlooked
by the
kit builder.
2. About
90%
of
the kits
that are
returned
to the Heath
Company
for repair
do
not function
properly
due to
poor
connections
and soldering.
Therefore,
many troubles
can
be eliminated
by reheating
all
connections
to make sure
that they are
soldered
as described
in the
"Soldering"
section
of the
"Kit Builders
Guide."
Be sure
there are no
solder bridges.
3.
Check
to
be sure that
the transistors
and
diodes
are in their
proper
locations.
Make
sure each
lead is
connected
to the proper
point.
4.
Check
the values
of the
parts. Be
sure in each
step that the
proper part
has
been wired
into
the circuit,
as shown
in the Pictorial
Diagrams.
It would
be
easy, for
example,
to install
a 47
kH (yellow-violet-orange)
resistor
where
a
4700 SI (yellow-violet-red)
resistor
should
have
been installed.
DIFFICULTY
5.
Check
for bits of
solder,
wire ends,
or other foreign
matter
which
may be
lodged
in the wiring.
6.
Be
sure all wires
and leads
connected
to the circuit
boards
have been
trimmed
as close
as possible to
the circuit
board foils.
7.
A review of
the "Circuit
Description"
may also
help
you determine
where
the trouble
is.
If
the
trouble is
still not located
after
the
"Visual Tests"
are
completed, and
a
voltmeter
is available,
check
voltage
readings
against
those shown
on the
"Schematic Diagram"
(fold-out
from
Page
67). Read
the
"Precautions for
Troubleshooting"
before
you make any
measurements.
NOTE:
All voltage
readings
were
taken with
a high impedance
input
voltmeter.
Voltages
may vary
as
much
as ±20%.
NOTE: In an
extreme
case where
you are unable
to resolve
a difficulty,
refer
to
the
"Customer
Service"
information inside
the rear
cover of
the Manual.
Your
Warranty
is located inside
the front
cover of
the Manual.
PRECAUTIONS
FOR
TROUBLESHOOTING
Be cautious
when
you test diode and
transistor
circuits. Although
they have
almost unlimited
life when
used properly,
they
are much more
sensitive
to
excessive voltage
or current
than tubes.