Eico HF-20 - Trouble Shooting Chart

TROUBLE
SHOOTING
CHART
SYMPTOM
CAUSE
REMEDY
Amplifier
causes
power line
fuse
to
blow.
Line cord,
J8, J9,
primary or
high voltage
secondary
windings
of Tl,
Incorrectly
wired.
Prt./h.v.
sec.
windings of
Tl
shorted.
(If the
amplifier
causes
the
line
fuse
to blow
again
when
connected
to the
line
with
5U4
GB
rectifier
V7 removed,
one
or
the
other of
the
above
causes
must
be
the
reason.)
V7
shorted
replace
after checking C26
V7
filament
not
lit.
Incorrect
wiring
of
fll.
leads
to V7
socket.
repair
5V
fll.
winding
of
Tl
open.
replace
Tl
Any
or
all
other
tube
filament
Open
lead
from
6.3
V winding
of
Tl
.
repair
not lit.
6.3 V
winding
of
Tl
open.
replace
Tl
DC
voltage
at
V7 cathode
(pin
8)
Is Incorrect
as
specified
below.
*
*
a)
No
voltage
Defective
V7
replace
C26 A
shorted
Internally
or
externally.
replace
or
repair
b)
High
Voltage
Connection
to
C26 A
from
pin 8
of
V7 broken.
i
repair
Connection
to center
tap
of
h.
v.
sec.
winding
of Tl
open.
repair
Output
tubes
V5
&
V6
over-biased
or not
draw
-
Ing
current.
see
trouble-shooting
typical
i
c)
Low
voltage
Excessive
current
drain
In amplifier.
see
trouble-shooting
typical
j
Defective
V7.
replace
Connect
a
phonograph
and
speaker
to
the
amplifier
as
described
In "Electrical
Connections"
and
set controls
for
phono
list-
ening.
Play
a
known
high
quality
LP
recording
on
the
phonograph.
If
there
Is no
output
to
the speaker
or
If
the
output
Is
low
or
audibly
distorted,
procede to
the
checks
for
those
symptoms.
If
there
Is
excessive
hum
In the
output,
disconnect
the
phono
Input cable
from
the
amplifier
and short
the
phono
Input
|ack
to
chassis.
If the
hum
disappears
the
trouble
Is
not In
the
amplifier
but
In the
phonograph
or
In
the
connection
to the
amplifier.
The
cause
of
phonograph
hum may
be a
metal
pick-up
arm
not
grounded
to
the
cable
shield
(try a
good
single ground
con-
nection
to
the
cable
shield
from
turntable
frame,
pick-up
arm,
and
cartridge
case),
direct
hum
pick-up by
the
magnetic car-
tridge
from
the
record
player
motor (try
using a
rubber
mat
on the
turntable
to
Increase
the
separation
of
the
pick-up
from
the
motor),
or
pick-up
from
a
power
transformer
or other
magnetic
field
In the
vicinity
(try
moving
phonograph
away from
suspected
source)*
Check
also that
the
phono
Input
cable
shielding
Is grounded
to
the
amplifier
chassis at
one
point only
through
the
skirt of the
Input
connector
where
It
plugs
Into
the
amplifier.
Finally,
try a
good
building
ground
such
as a
connection^
from
a
cold
water
ptpo
terminated
under
speaker
terminal
"G"
on the
amplifier.
Do
not
connect
such
a
ground
wire
to
other
components
In
the
system.
Excessive
hum
on
other
Inputs
may
be
checked
In
a
similar
manner.
Disconnect
the
Input
cable
In question and
short the
pwtlcular
Input
fack
to
the
chassis.
If
the hum
disappears,
the
trouble
Is
external
to the
amplifier.
Note
that
on all
Inputs,
the
braid
of
the
Input
cable
should
connect
to
the
amplifier
only
through
the
skirt of
the
Input
connector.
The
cause and
remedies
for
the
following
symptoms
are
then
based
on
the
assumption
that
checks
made
In the
manner
described
above
have
eliminated
the
possibility
of
the
trouble
being
external
to
the
amplifier.