the
outer
braid conductors of the phono irtput
cables),
direct horn pick-up by the magnetic cartridge
from the
record player motor (try
using a rubber mot <hi the turn-
table to increase the separation
of the plck-^p from the
motor), or
pick-up
from
a power transformer or other
mag-
netic
field in
the
vicinity (try moving
phonograph awoy
from
suspected source). Check
also that the phcmo input
cable shielding is grounded
to the amplifier chossisatone
point only, through the
skirt of the Input
connector where
It
plugs
into the
amplifier. Finally, try
a good buildirtg
ground
such as a connection from
a cold woter pipe ter-
minated under speaker terminal
"G'‘on the amplifier.
Do
not connect sucha
ground wire to other components
in the
system.
If possible, let eoch channel
be connected to the
amplifier
using
a
separate shielded cable to
the amplifier
input.
It is also desirable thot
the ground leads
on
both
cables not be
connected together at any
point —not even
at the cartridge.
However, with
some cartridges. It will
not be
possible to do this.
In
this cose,
just disregard this
last Instruction.
Excessive hum
on other inputs maybe
checked inastmllar
manner. Disconnect
the Input cable
Inquestlon and
short
the particulor
Input jack to the
chassis. If the
hum dis-
appears, the
trouble Is externol to
the amplifier.
h(ote
that
on
all Inputs, the braid of
the Input coble
should
con-
nect to
the
amplifier
only through
the
skirt
of the
input
connector. The
eouse and remedies
for the
following
symptoms are
then based
on the assumption
that checb
mode
In the manner described
above
have eliminated the
posiIbiMtyof the trouble
being externol
to the amplifier.
If the trouble
Is no output or low output,
cheokAC signal
voltages
and DC operating voltages storting
at the input
and work step-by-step toward the output
Ir^ each ampli-
fier. Set the
LWEL
controls to
maximum
(10),
the BASS
and TREBLE controls to their
mid-points
(0),
the SELECTOR
switch to PHONO
and the MODE switch to
STEREO NOR-
MAL
or
REVERSE. Use
a
1000 cycle sinewove
signal, such
as supplied by the EICO 377 Sine
& Square Wove Audio
Generator,
In
addition,
use
a precision
iOO: I attenuator
to permit
obtaining
a
level of
0.004 volt fed Into
MAG.
PHONOfrom
on audio generotoroutpu
t of 0.
4
volts,
which
con easily be measured
on the lowest
AC volts range
of
your VTVM (also
improves signal to
hum from generator).
Use Q high Input
Impedance
VTVM
for
all
AC signal vol-
tage
measurements;
a VTVM or
20, OOOfVv VOM
for
DC
volts
measurements.
If
the trouble is
an excessively
distorted output,
try tube
replocement, signal tracing, or
procede directly to vol-
tage
and resistance measurements.
When the
defective
stage Is localized, procede to
a re-
sistance and voltage check of the stage,
using the data
In
the resistonce and voltage chart. Disconnect
the pre-
amplifier from
the power line ond dischorge capacitors
prior to making any resistance
check.
SERVICE
If trouble developes
in your Instrument
which you can not
remedy yourself,
write to
our service deportment listing
all possible indications that
might be helpful. If desired
you may return the instrument
to ourfoctory
where it will
be placed
In
operating
condition for
$8.00
plus the cost
of parts replaced due
to their being damaged
In the course
of construction.
NOTE:
Before
returning this
unit,
be
sure
all parts ore securely mounted.
Attach o tag
to
the
Instrument, giving
your home
address
and
the trouble witf
the unit. Pack
very eorefully
In o
rugged
container,
us-
ing sufficient
packing material (cotton,
shredded news-
poper,
or
excelsior), to moke the
unit completely
Immov-
able within
the eontolner.
The origlnol shipping
carton
Is satisfoctory,
providing the
original Inserts
are used or
sufficient
packing moterial
Inserted to
keep the Instru-
ment
immovable. Ship
by prepaid Railway
Express, If
possible, to Electronic
Instrument
Co.,
Inc.,
33-00 North-
ern Blvd.
,
Long Island City
1,
New York. Return ship-
mentwlll be mode
byexpress collect. Note that
a carrier
connot be
held liable for damages
in transit If packing
IN
HIS OPINION, Is insufficient.
MODEL
HF-05 SPECIAL
NOTE
The
high gain of the Model HF-85
low level Inputs
(MIC,
MAG. PHONO, TAPE HEAD) requires
that shorted
RCA-
type phono plugs be inserted into
all unused low level
in-
put jacks.
A number of RCA-type phono
plugs are sup-
plied with
every unit, and it remains
only to short out
each of the plugs required for this
use.
10
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