Troubleshooting Chart - Eico HF-12 Instruction Manual

TROUBLE-SHOOTING CHART
SYMPTOM
Amplifier causes
power
line fuse
to
blow. Power
line fuse
blows a-
gain with
V6
out of socket.
Amplifier causes power
line fuse
to
blow.
Power
line
fuse does not
blow again with
V6
out
of socket.
Any
or
al
I
tube filaments not
lit.
DC
voltage
at
V6
cathode
(pin 9)
is
incorrect
as
specified
below.
a)
No
voltage
b)
High
voltage.
c)
Low voltage.
Excessive
hum
on
mag. phono
or tape
head.
Excessive noise on
mag. phono
and tape head
Sustained
oscillations.
Sustained
microphonics on mag.
phono and
tape
head.
Hum
on
all
inputs
CAUSE
Line cord, J6, primary or
high voltage
secondary windings of T2 shorted internally
or externally (wiring).
V6, C17, V4, V5,
or
T1
primary shorted
internally or externally.
Open
lead from 6.3
V
winding
of T2
6.3V
winding
of T2
open.
Defective
V6
C17
shorted internally or externally.
Connection from
Cl
7
to
pin 9 of
V6
broken.
Connection
to
center
tap of
h.v. secondary
winding
of T2 open.
Output
tubes
V4
&
V5
over-biased or not
drawing
current.
Excessive current drain
in
amplifier.
Defective
V6
VI defective
Fil.
leads dressed too close
to
grid lead.
Tube
shield not
making
electrical contact
to
base
or base not
making
electrical
con-
tact to chassis.
Shielding
and grounding
of wiring to input
jacks
not exactly
as instructed
and shown
in
drawings.
VI
socket and
contacts dirty.
Poor dress of output transformer T1 leads
VI
defective.
V2
defective, not properly shielded,
or
dirty sockets
and
contacts.
Dress
of
power
transformer T2 leads.
REMEDY
Replace
or repair.
Replace or
repair.
Repair
Replace
Replace
Replace
or repair.
Repair
Repair
See trouble-shooting
typical tube
stage.
See trouble-shooting
typical
tube
stage.
Replace
Replace
Dress
fil
leads
away
from
grid lead.
Check and
correct
Correct
Clean throughly with carbon
tetrachloride.
Dress
all
input leads
and
T1
leads
away, from each
other.
Keep
T1
leads
away
from input
jacks.
Replace
Replace,
correct, or clean.
Correct
7