Eico HF-20 - Troubleshooting and Maintenance; Maintenance

(amounts of
boss
boost
and
treble
cut)
by
the
amplifier
to
restore
the
original
balance.
The
specific
equalization
required
depends
upon
the brand
of
the
record,
and
the
equalization
which
should
be
used for
each
record
brand
(for
recordings
made
before
1954)
ts
listed
In the
first
column
to the
right of
the
company's
name
In the
chart
below.
In some
eases,
additional
ad|ushnent
Is
required
with
the
BASS
control
to
match
the
equalization
employed
by
the
particular
company
more
exactly.
Since
Spring
1954,
the
RIAA
(new AES)
recording
curve
has
been adopted
byalmast
all
record
companies
and
rec-
ords
of
which
the
masters
were
made
after
this date
will
be
properly
equalized
at
the
RIAA
position
unless
the
company
Involved
has
not
made
the
change
(see
second
column
In chart).
RECORD
EQUALIZATION
SELECTION
Record
Label
Equalization
Since
Spring
1954
|
Allied
RIAA
RIAA 1
Angel
RIAA
RIAA
Atlantic
COL,
Bass
4-2*
RIAA
Amer.Rec.Soc.
RIAA
RIAA
Bartok
COL,
Bass
+2
do
change
I
Blue
Note Jazz
RIAA,
Bass
+1
RIAA
Boston
COL
RIAA
I
Caedmon
RIAA
RIAA
I
Camden
RIAA
RIAA
Canyon
RIAA,
Bass
+1
RIAA I
Capitol
RIAA,
Bass
+1
RIAA I
Capita
l-Oetra
RIAA,
Bass
+1
no change
'
1
Cetra-Sorla
COL
no change
1
Colosseum
COL
RIAA I
Columbia
COL
RIAA 1
Concert
Hall
RIAA,
Bass
+1
RIAA I
Contemporary
RIAA,
Bass+1
RIAA
I
Cook
RIAA*
RIAA
|
Dacca
COL
RIAA I
EMS
RIAA,
Bass
+1
RIAA 1
Elektra
COL,
Ban
42
no change
1
Epic
COL
RIAA
I
Esoteric
RIAA
RIAA
I
Folkways
(most)
COL,
Bass
42
no
change
1
Good-Time
Jazz
RIAA,
Bats
41
RIAA
Haydn
Society
COL
RIAA 1
Record
Label
Equlllzatlon
Since Sprl
1954
L'Otseau-Lyre
LON RIAA
London (fftr)
LON
RIAA
Lyrlchord,
old
COL
or
RIAA
RIAA
Lyrlchord,
new
COL,
Bass
42
RIAA
Mercury
RIAA,
Bass
41
RIAA
MGM
RIAA
RIAA
Oceanic
COL,
Bass
42
RIAA
Pactflc Jazz
RIAA
RIAA
Philharmonic
RIAA,
Bass
41
RIAA
Polymusle
COL,
Bass
42*
RIAA
RCA
Victor
RIAA,
Bass 42.5
RIAA
Remington
COL, Bess
42
RIAA
Riverside
RIAA
RIAA
Romany
RIAA
RIAA
Savoy
RIAA
RIAA
Tempo
RIAA
RIAA
Urania,
most
COL,
Bos
42
RIAA
Urania,
some RIAA,
Bass
42
RIAA
Vanguard
COL
RIAA
Bach
Guild
COL
RIAA
Vox
COL
RIAA
Walden
RIAA
RIAA
Westminster
COL, Bess
42
no change
European
78*s
Eur
78
Older
Amer.
78's
AM 78
*
Except
use
EUR
for
binaural.
Inside
band
only.
MAINTENANCE
Your
amplifier
should
require
little
service
except
for
normal
tube
replacement.
If
desired,
the
6L6GB
output
tubes
may
be
replaced
by
the
6L6
GA
or
the
6L6
metal
tubes
aid
also
by
the
premium
5881
tubes
without
circuit
changes.
When
replacing
output
tubes.
It
Is
desirable
to
use
matched
pairs
of
tubes
for
the
lowest
distortion.
To
facilitate
servicing,
remedial
and
trouble-shooting
procedures
have
been
provided
In the
TROUBLE
SHOOT-
ING
CHART
that
follows.
VOLTAGE
and
RESISTANCE
CHARTS
are
also
provided
as
an
aid
to
locating
defective
components.
On
the
schematic
diagram,
AC
mid-fre-
quency
(1
kc)
voltage
sensitivities
are
shown
at
most
of
the
grids
for
full
20watt
power
output
In order
to
permit
a
careful,
stage-by-stage
check
of the
operation.