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TROUBLE-SHOOTING CHART
SYMPTOM
Amplifier causes
power
line fuse
to
blow. .Power
line fuse
blows a-
gain with
V9
&
VIO
out
of their
sockets.
Amplifier causes
power
line fuse to
blow.
Power
line
fuse
does not
blow
again with
V9&
VIO
out
of their
sockets.
Any
or
all
tube filaments not
lit.
(except
VI
VI
filament not
lit.
I
Output
tube
bias too
high
(re-
sulting
In
distorted
output
wave-
form).
DC
voltage
at
V9,VI0
cathodes
(pin 3)
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, J9,
JIO,
primary
or
high voltage
secondary windings
of
T2
shorted Internally
or externally (wiring).
V9, VIO, C31, V5, V6, V7, V8,
or
T1
pri-
mary
shorted Internally or externally.
Open
tube filament.
Open
lead from
6.3
V
winding
of T2.
•
6.3
V
winding
of
T2 open.
Open
VI
filament.
No
connection
or
poor connection
to
pin
5
(fll.
)
of
VI
from
common
cathode con-
nection
of
V5, V6, V7, and V8.
Pin
4
(fll.)
of
VI
not
grounded.
Same
as
above
If
VI
filament not
lit.
Open
R26
If
VI
filament
Is lit.
Defective
V9
or
VIO
C31
shorted Internally or externally.
Connection
from
C31
to
pin
3 of
V9
&
VIO
broken.
Connection
to
center
tap of
h.v. secondary
winding
of
T2 open.
Output
tubes
V5,V6,V7,V8
over-biased
or not
drawing
current.
May
result
from
open R26,open
filament
or
defective
con-
nection
to
VI
filament.
Excessive current drain
In
amplifier.
Defective V9,
VIO.
VI
defective
Fll.
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
cantacts
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.
Replace
or repair.
Replace
or repair.
Replace
or repair.
Replace
Replace
or repair.
Repair
Repair
Replace,
repair, or
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
8
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