In Case Of Difficulty; Visual Tests; Precautions For Troubleshooting - Heathkit HD-1250 Manual

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.