Heathkit SW-7800 - Page 7

Heathkit
Page
95
NOTES:
The
resistance
readings
in
the
following
steps
were
taken
with
a
VI'VM.
Readings
taken
with
other
ohmmeters
(because
of
different
measuring
voltages
and
currents)
may
be
con:
siderably
different
‘The
internal
wiring
of
most
ohmmeters
is
such
that
the
positive
terminal
of
the
battery
is
connected
to
the
negative
(black)
or
com-
mon
test
lead.
In
some
ohmmeters,
this
wiring
is
interchanged,
and
erroneous
readings
may
result.
Interchange
the
ohmmeter
leads
if
the
measurements
do
not
check
out
correctly
the
first
time.
()
Temporarily
remove
meter
lamp
PLi
frou
socket
METER
CONNECTIONS
METER READING
POSSIBLE
CAUSE
OF TROUBLE
POSITIVE
LEAD
COMMON
LEAD
(Either
prong
ofthe
line
cord
plug
Grouna
2
MO
minimum
with
Power
‘A.
Wiring
of
switch
sw,
switch
on
or
off
B.
Wiring
of
transformer
T
()
Other
prong
ofthe
line
cord
plug,
Ground,
2
MO
minimum
with
Power
A.
Wiring
of
switch
SW.
‘switch
on
or
of
B.
Wiring
of
transformer
1
()
Sethe
ohmmeter
to
the
Rx
10
range.
(_.)
Either
prong
ofthe
line
cord
plug
Other
prong
INFINITE
with
the Power
A.
Witing
of
switch SW,
switch
off.
B.
Wiring
of
transformer
11
)
Either
prong
ofthe
line
cord
plug,
Other
prong.
‘Approx.
50
9110
100
9
with
A.
Wiring
of
switch
Sw,
the Power
switch
on.
B.
Wiring
of
transformer
m1
()
+
(plus) lead
of
capacitor
C511
Ground.
Approx.
1SOFRE80.0.
A.
Diodes
D425
through
(see
Pictorial
6-1)
SOQ.
Tego.
Daze.
B.
Resistors
R509
or
Sit
C.
Capacitors
C508,
509,
or
C511
().
Reinstall
meter
lamp
PL1
in
its
socket.
This
completes
the
“Initial
Tests.”
Proceed
to
“Alignment.”