Eico HF-81 Service manual
MODEL Hf -
general description
GENERAL
The EICO Model HF-
phonic control center and a pair of 14watt amplifiers,
on one
chassis. With it
control accurately any stereophonic source (tape, discs, or
broadcasts) and feed it through the
watt amplifiers to a stereo pair of speaker systems.
you playa monophonic
channe I adds up to a total of
systems. If you desire,
in parallel and driven byone
whi Ie the other preampl
an external power amplifier. In this way your old ampli-
fier can be put to use in a stereophonic
tion is of the "Iow silhouette
dispense with cabinetry if desired.
FEATURES
81 is a complete high fidelity stereo-
you can select preamplify, and
self-contained dual 14
When
source, the 14 watts available per
28 watts for your two speaker
both amplifiers can be connected
preamp I ifier-control section
ifier-control section is free to drive
system. Construc-
" type that permits you to
all
DUAL 14
STEREO AMP
channel) and two auxil iary B
Input Selector switch on front panel has positions for
ing FM tuner output to one
, or FM tuner to one
other
WATT HI-
- PREAMP
inputs (one in each channel).
channel and AM tuner to
channel and FM Multiplex
adapter output to other.
3. May be
preamplifiers,
set free to operate an external
other preampl ifjer-control section used to drive
ternal power
speaker connection terminals. A top -
switch permits choice of operation.
4. Ganged
used as either two independent amplifier-
or one preamplifier-control section may be
power amplifier and the
both in-
ampl ifiers
level controls and a separate focus (balance)
connected in parallel at
of-chassis sl ide
control.
5.
Independent full-range bass and treble tone controls
in each channel. Tone
controls of the low
distortion
variable cross-over feedback type.
feed-
the
1. Separate low
phono, tape head, and microphone. Circuitry
level input in each
channel for mag.
carefully
designed to provide the high gain required by tape heads
and high quality, low output mag. cartridges without
hum
and noise problems. A front panel switch permits choice
of the proper
NARTS tape head equalization for
7 1/2 & 15 or 3 3/4ips tape
2. Separate
Multiplex. Also two
high level inputs
auxiliary A
speeds.
for AM,
inputs (one in each
either
FM, and FM
6. Identical
Williamson type, push-
plifiers with high quality output
7. Hum balance
convenience outlets.
8. EICO "
zontal chassis for proper layout and component separation.
Easy console installation,
ing and adapatability to any panel thickness.
control, panel-mounted fuse, pi lot
low silhouette
Copy,;ght I1d 1958 Electronic Instrument Company, Inc.
" construction employing hori-
if desired
pull EL84power am-
transformers.
lamp,
, with complete shield-
SPECIFICATIONS *
Output Power:
1M Distortion
at 10 watts.
Frequency Response:
HarmonicDistortion:
20 watts at I
less than
28 watts continuous; 56 watts peak.
(60c &7kc at 4:
: 2% at 28 watts; 0.
(2w):I:O. 5db 10c to 1O0kc.
16 watts at less than 1% 30c to lOkc;
ess than 1 % 40 c to 10 kc; 28 watts at
1% 50c to
5kc; 8.
4 watts at
2% at 20c.
Transient Response
(4usec rise time) negligible ringing,
on 10kc square wave.
: excellent square
wave reproduction
Transient Distortion (60cps tone burst)
fu II power.
Inverse Feedback: 20db
Stability Margin:
Damping Factor: above 8, 20 cps - 15 kc.
12db
less than
rapid settl ing
less than 1% at
** Hum & Noise Level (below
60db; tape head - 51
iI iaries
Tone Control Range:
Speaker Connections: 4 8, and 16 ohms.
- 75 db.
::I:15db at
rated output): mag. phono
db; mic
db; tuners, aux-
- 57
50c and 10kc.
Tubes: 4 - ECC83/12AX7, 2 - ECC82/12AU7, 4- EL84,
2 - EZ81.
Size:
Weight:
15" wide, 4 3/4" high, 10 1/2" deep.
241bs.
* Where power output is involved, figures are given for
two channels combined; divide power output figures by
two for specifications of each
channel alone. Design
property specifications refer, of course, to either or both
channels.
flat"
** Measured with tone controls set "
maximum, and
FOCUS control set for maximum gain in
, LEVEL control
channe I checked.
Sensitivity (input for rated output):
tape head 7.
5mv; mic
5 ips - 2 mv; tape head 3.
- 6mv;
tuners, auxiliaries - 0.
mag. phono 4mv;
75 ips
5V.
mechanical installation
GENERAL
a) HEAT DISSIPATION (VENTILATION): In common with
other electronic equipment
able heat in normal operation. Unless continuous and
quate air flow is
obtained around the heat producing ele-
ments, these elements will over-
, the HF-Sl produces consider-
ade-
heat and their useful life
will be greatly curtailed.
It is useful to understand the process of convection where-
by heat is removed in judging the
Air heated by the heat-
producing elements expands and
suitability of a location.
rises; cool air is drawn from beneath to take the place of
the heated air. In
motion which continually
fier. (In particular,
major heat-
producing elements; the four EL84 output tubes
this manner, a
removes heat from the ampli-
we are mainly
and the two EZSl rectifier tubes.
ment to or constriction of the airflow, the essential
stream of air is set in
concerned with the
) If there is any impedi-
process
of heat removal will be adversely affected.
Adequate ventilation will be
installed in an open-
back console provided that the top
of the amplifier is spaced at least
shelf mounted above it.
rear, provide several large holes or
as high up in the cabinet back
nate, holes
of the cabinet.
effective ventilation requires provision for cool air
ter at the bottom and hot air to leave at the top.
may be provided in the sides, bottom, or top
The important thing to
If the amplifier is not
situated on an open surface or on a shelf of a
provided if the amplifier is
two inches below any
If the cabinet is enclosed at the
slots as low down and
as possible. As an alter-
remember is that
to en-
installed in a console, it
may be
boakcase~
Four rubber feet are also provided so that the amplifier will
not mar the surface of furniture on which it is placed.
b) EASY ACCESS TO CONTROLS: Mount the amplifier
at a height which will permit easy manipulation of the
trols. Tuner controls should be located nearby.
c) ACCESSIBILITY TO PARTS: . Tubes are the most fre-
quently replaced items in electronic equipment. If
con-
the
amplifier is installed in a console, sufficient space should
be alloted to reach and
Furthermore, input and output
should be accessible to permit easy
tem components for
connection of a portable tape recorder which is
way when not in use.
back of the console in which the amplifier is
arrange them so they will not
remove any tube in the amplifier.
terminals of the ampl ifier
interchanging of sys-
comparison, and connection or dis-
stored a-
If antennas are strung around the
installed,
interfere with access to the
amplifier.
d)
ACOUSTICAL ISOLATION:
are installed in the
same cabinet (not recommended))' pro-
If amplifier and speaker
vide sufficient separation to minimize mechanical speaker
vibration reaching the amplifier. The
minimum separation
is about one foat.
CONSOLE MOUNTING
a) 0 erationsonconsolefront anel
fier mounting:
the face of the console so that the top of the mounting sur-
face line on the template
amplifier mounting shelf. Note:
Tape the panel template provided to
is level with the top of the
reliminar to am li-
When shelf is not avail-
able, tape the template atanyconvenientspot on the face
of the console. (2) Use an awl
centers of the four extreme outer
or a nai I to pierce the
holes for mounting the
control plate, to transfer their locations to the console
panel beneath. (3) Trace out the rectangular cutout with
an awl or nail and then pierce the centers of the
holes)' one in each corner of the cutout.
panel template. (5) Drill the
sole panel, one in each corner of
area. Cut out the rectangular piece with a keyhole sawl
four 1/2" holes in the con-
the rectangular cutout
four 1/2"
(4) Remove the
using the four 1/2" holes as starting holes.
b) Am lifier mounting in console: (1) Pull off the control
knobs. 2 Remove the four screws that fasten
to the side pieces and
two screws and nuts that fasten the
bezel. The bezel
Fasten the control plate to the console panel with the two
#4x3/S wood screws supplied. (5) If the rubber feet
been inserted irwhe bottom plate, remove them. (They
be pried out with a thin screwdriver. ) (6) Place the unit -
remove the bezel. (3) Remove the
control plate to the
is not used in
console mounting. ~)
the bezel
have
may
on the mounting shelf and slide it forward until the slide
switch
slide switch accessible from the front; the control shafts
should be approximately centered in the
holes in the control plate.
the outline of the side and rear
sl,lpport bracket is
up against the panel and the
corresponding
(7) With a sharp penci!l draw
bottom edges on the chassis
shelf. As the bottom plate falls short of the full width by
3/16" on each side, draw new side edge
side the original side edge
lines. (S)
knobs and take the chassis off the shelf.
6screws which fasten the bottom plate to
Place the bottom plate exactly in the outl
shelf and mark the position of the center hole on the left
side and the center hole on the right side. (11)
lines 3/16" in-
Now remove the
(9) Remove the
the chassis. (10)
ine drawn on the
Remove
the bottom plate and dril! each of the marked holes on the
shelf to a diameter of 1/4"
plate to the chassisl withthefourof the six
previously removed, using the two holes at the
two holes at the front of the
chassis on the shelf
previously drawn, and restore the knobs. This time
l positioning
sure that the indicator dot on each
control position. (14) From the bottom side of
insert a #S
xl" screw, with a 1/2" flat
the head, through both the left and right side
These screws engage the stamped nut over each hole on
the chassis flange and when tightened secure the
to the shelf.
(12) Refasten the bottom
#8x3/Sscrews
rear and the
chassis. (13) Replace the
it exactly in the outline
make
knob agrees with the
the shelf
washer against
center holes.
chassis
electrical installation
The HF-
81 can be used in two ways
system. In all
cases, plug monophonic sources and one
for a stereophonic
track of monophonic/stereophonic sources in the channel
1 inputs; plug the other track of stereo sources in the
nel 2 inputs. It is assumed in what follows that a
phonic phono cartridge is being used. Monophonic
refers to playback of a monophonic recording with a stereo-
chan-
stereo-
phono
phonic cartridge.
a) INTERNAL POWER AMPLIFIERS OPERATED SEPARATE-
LY, EACH DRIVING ONE
SPEAKER OF A STEREO PAIR.
This arrangement is used when there is no other amplifier
the user desires to include in the system. The
SEL. sl ide switch on top of the chassis must be set
arate. Signal connections are all internal, so only
speaker connection need to shown (Fig.
la, rear chassis
SERVICE
to SEP-
the
view). The internal arrangement ion in the HF-81 at each
of the positions of the FUNCTION selector are
Figs. Ib, lc, Id
, Ie, If
, and 19, as an aid to understand-
shown in
ing the operation with this arrangement.
FIG.
CHECK AMPL. 1
CH. I LOW
LEVEL INPUTS
CH.
IPREAMP~
16 8
32
(J) (J) (f)
TO MATCHING
TAP
FIG. la. SPEAKER CONNECTIONS
CH. 1 HIGH
LEVEL INPUTS
CH.
CH.
SPKR.
CH. 1
TAPE OUT
CH.
32
(J)
TO MATCHING
TAP
POWER AMP
CH.
SPKR.
SPEAKER
CH.
FIG.
CHECK AMPL. 2
FIG. Id
STEREO NORMAL
FIG. Ie
STEREO REVERSE
CH. 2 LOW
LEVEL INPUTS
CH. 1 LOW
LEVEL INPUTS
CH. 2 LOW
LEVEL INPUTS
CH. 1 LOW
LEVEL INPUTS
CH. 2 LOW
LEVEL INPUTS
PREAMP
CH.
~:'~P
CH.
2HIGH CH.
CH.
LEVEL INPUTS T APE OUT
CH. 1 HIGH
LEVEL INPUTS
2 HIGH CH.
CH.
LEVEL INPUTS
CH. 1 HIGH
LEVEL INPUTS
CH.
TAPE OUT
SEP ..
TAPE OUT
CH.
TAPE OUT
SEP
POWER AMP
SERVICE SEL.
I PO
CH.
AMP
SPEAKER
CH.
SPEAKER
CH.
~~~~R
SPEAKER
CH.
SPEAKER
CH.
CH. 2 HIGH
LEVEL INPUTS
CH.
TAPE OUT
FIG.
MONOPHONIC
TAPE, TV
TUNER,
CH. 1 LOW
LEVEL INPUTS
CH. 1 HIGH
LEVEL INPUTS
CH.
TAPE OUT
SEP
CH.
TAPE OUT
SPEAKER
CH 1
SPEAKER
CH.
CH. 1 LOW
LEVEL INPUTS
FIG. Ig
MONOPHONIC PHONO
2 LOW
CH.
LEVEL INPUTS
b) INTERNAL
TOGETHER AT THE INPUTS AND
OUTPUTS) TO DRIVE ONE SPEAKER OF A STEREO PAIR.
This arrangement is employedwhen the useralready has a
high quality amplifier (usually 20watts or more if it is to
be worthwhile) which he desire to include in the
The preamp-
ular CHI tone control feeds the
amplifiers; the preamp-tone control combination including
the regular CH2 tone control feeds out
TAPE OUT jack to an external power
VICE SELECTOR switch on
COMbined position for this service in order to disconnect
the input of the CH2 power amplifier
the CH2 tone control and connects it instead to the input
of the CHl
amplifiers are paralleled at the outputs
external jumper connected between corresponding speaker
connection taps, The external
speaker connections are shown in Fig,
arrangements in the HF-
FUNCTION selector are
, and 2g, as an aid to
this arrangement.
POWER AMPLIFIERS COMBINED (TIED
PARALLELED AT THE
system.
tone control combination including the reg-
combined internal power
through the CH2
amplifier. The SER-
the chassis must be set at the
from the output of
power amplifier, The CHI and
CH2 power
, as shown
, by an
signal connection and the
2a. The
81 at each of the positions of the
shown in Figs. 2b,
understanding the operation with
internal
2c, 2d, 2e,
CH. 1 HIGH
LEVEL INPUTS
2HIGH CH.
CH.
LEVEL INPUTS
TAPE
OUT
.INPUT
* On integrated
OUTPUT lack; on HF521 feed into
OVER INPUT jack,
ELECTRONIC CROSSOVER IN and
CH.
T APE OUT
SERVICE SEL
SEP
T APE OUT
CH.
BASIC
~RNA
EXT
POWER AMPLIFIER
~~~:MP
amplifiers HF20,
after severing
FIG. 2a. SPEAKER &
SIGNAL CONNECTIONs.
SPEAKER
CH.
SPEAKER
CH.
CH.
(f)
. I
::! I
:Q it
~ i
~ I
'" I
a I
"" I
1___-
HF32 feed into
ELECTRONIC CROSS-
connection between
OUT jacks.
EXTERNAL
TAPE
FIG.
CHECK AMPL.
CH. 1 LOW
LEVEL INPUTS
CH. 1 HIGH
LEVEL INPUTS
CH.
TAPE OUT
SPEAKER
CH.
FIG.
CHECK AMPL. 2
CH. 2 LOW
LEVEL INPUTS
CH. 2 HIGH
LEVEL INPUTS
CH.
TAPE OUT
SPEAKER
CH.
FIG.
STEREO NORMAL
FIG.
STEREO REVERSE
CH. I LOW
LEVEL INPUTS
CH. 2 LOW
LEVEL INPUTS
CH. I LOW
LEVEL INPUTS
CH.
2 LOW
LEVEL INPUTS
CH. I HIGH
LEVEL INPUTS
CH.
2 HIGH
LEVEL INPUTS
CH.
TAPE OUT
SPEAKER
CH.
CH.
TAPE OUT
SPEAKER
CH.
SPEAKER
CH.
FIG.
MONOPHONIC
T APE,
TUNER,
CH. I LOW
LEVEL INPUTS
CH. 2 HIGH
LEVEL INPUTS
CH. I HIGH
LEVEL INPUTS
CH.
TAPE OUT
SPEAKER
CH.
SPEAKER
CH.
CH.
TAPE OUT
SPEAKER
CH.
FIG.
MONOPHONIC PHONO
CH. 1 LOW
LEVEL INPUTS
2 LOW
CH.
LEVEL INPUTS
CH. l HIGH
LEVEL INPUTS
CH.
T APE OUT
SPEAKER
CH.
COM
c) INPUTS: There are identical pairs of MAG. PHONO,
TAPE HEAD
ILIARY B inputs -one of each pair in
MICROPHONE, AUXILIARY A, and
channell and chan-
AUX-
nel 2 - and each is identified accordingly by the suffix
1 or 2. The MAG. PHONO,
TAPE HEAD
PHONE pairs of inputs are all II low level" inputs, mean-
ing that they all feed through a preamplifier/equalizer
stage in either channel
AUXILIARY Bpairsofinputs are
ing that they enter either channel
the preampl ifier/equalizer stages.
FM Multiplex inputs are also "
are internally selected in pairs
- by the
INPUT SEL. switch.
l or 2. The AUXILIARY A and
high level" inputs, mean-
l or 2 at a point after
The AM, FM and FM-
high level inputs , which
- one for each channel
At the MONAURAL posi-
tion of the FUNCTION SEL., AM only is selected at
FMposition of the INPUT SEL., and FMonlyis select-
AM-
ed at the FM - FM MULTI. position of the
l) MAG.
are intended for the two outputs of a stereo magneti c car-
tridge, or for a stereo
The correct method for wiring a three terminal cartridge
is shown in Fig. 3. If the cartridge is a four terminal
type)' short the two inside
PHONO 1, MAG. PHONO 2: These inputs
ceramic cartridge with adaptors.
terminals of the cartridge to-
MICRO-
, and
INPUT SEL.
the
gether and treat it exactly as if it were the single center
terminal shown in Fig. 3.
The loading presented to each
output of the cartridge by each MAG. PHONO input is
100,000 ohms. If
by the particular cartridge used, connect a shunt
of appropriate value from each outside terminal of the car-
tridge to the center
actually by mounting a 3-
side of the phonograph mounting board at a
lead break-out from the pickup arm.
are then wired to this terminal strip as
The value of each of the
a lower loading resistance is
(common) terminal. This can be done
post terminal strip on the under-
These shunt resistors
shown in Fig. 3.
two shunt resistors (Rs) can be
determined from the desired loading resistance (RI) by this
100,
formula
Rs =
or th is tabl e; for RI = 50KQ, use
use Rs = 50KQ; for
RI = 25KQ, use
000 x RI
00)' - RI
Rs = 1 OOKQ; for RI
ohms
Rs = 33KQ.
required
resistor
point near the
:: 33KQ,
2 HIGH
CH.
LEVEL INPUTS
CH.
T APE OUT
SPEAKER
CH.
* NOTE: All ceramic cartridge manufacturers have devel-
oped simple networks which when
connected the outputs
of their cartridges result in a characteristic identical to
that of magnetic
mended adaptor for the
cartridges. By interposing
particular ceramic cartridge be-
tween the cartridge outputs and the MAG.
puts of the ampl ifjer, it is possible to use the MAG.
inputs for the ceramic cartridge
Adaptor networks are given in
ticular ceramic cartridge
and can be built on a terminal
strip mounted on the underside of the
may be available in convenient
with excellent
the literature for the par-
phonograph base, or
component form from the
cartridge manufacturer. Stereophonic
(Ronette "
rectly to auxiliary high level inputs.
2) TAPE HEAD
Binofluid II OV and BF40) can be connected di-
1, TAPE HEAD 2: These inputs are in-
the recom-
PHONO in-
PHONO
results.
crystal cartridges
tended for direct connection to the two outputs of a stereo
tape playback head. A front panel slide switch permits
choice of NARTB tape head equalization
(& 15) ips or3
presented by each tape head input is 100,000 ohms.
3) MICROPHONE 1, MICROPHONE 2: These inputs are
314
ips tape speeds. The loading resistance
either for71/2
intended for rec~~:ving the output signals directly from
two separate microphones. It is preferable that the microphones used be of the high impedance type.
4) AUXILIARY AI, AUXILIARY A2: These inputs are
intended for either a stereophonic or monophonic high
level source. A stereophonic high level source might be
a stereo tape deck with built-
for both tracks.
A monophonic high level source might
be a monophonic crystal cartridge or tv sound.
monophonic source intoAUXJLlARY A 1, leaving
ILIARY A2 input unused. Note that the input
at all these high level inputs is 0.
low for ceramic cartridges requiring 2 to 3 megohms in-
put impedance. For
ceramic cartridges, use the MAG.
PHONO inputs with the simple adaptor networks recom-
mended by the manufacturers. For
cartridges (Ronette "Binofluid" OVturnover and BF40 sin-
gle needle), the 0.
5 megohm load provided at the high
level inputs is exactly the loading impedance required.
in playback equal ization
Plug a
theAUX-
impedance
5 megohm, which is too
stereophonic crystal
STEREO MAG.
CARTRIDGE
5) AUXILIARY Bl, AUXILIARY
ILIARY A 1, AUXILIARY A2 above.
6) AM: This input is intended for AM tuner or the AM
output of an FM-AM tuner where the FM
are independent.
B2: Same as for AUX-
and AM sections
FIG. 3
TO MAG.
INPUT
TO MAG. INPUT 2
mentioned sources to the correspondmg
jack. Unless the source has a low-impedance output such
as a cathode follower (with which up to 50ft.
can be used), use the shortest possible connection and
low - capacity shielded cable (cable having
amplifier input
of cable
as low as
25mmfd capacitance per foot is available).
7) FM:
where the FM and AM sections are independent.
8) FM MULTIPLEX: This input is intended to receive the
This input is intended for an FMor FM-
AM tuner
output from an FM Multiplex adaptor.
NOTE: A shielded cable with a shielded "
plug should be used to connect from each of the above-
HF 81
phono-type
TAPE
OUT
cgJ
e) POWER CONNECTIONS: The line
must be plugged into a house outlet providing normally
117 volts, 60 cycles AC power.
tacle on the rear chassis can be used, if desired
cube tape to provide
equipment. This convenience receptacle is not switched
or fused and provides 117VAC at all time'S""rregardless
of whether the HF-81 is turned on or off.
HUM ADJUSTMENT
After checking the ampl ifier for proper operation, remove
all input cables to the amplifier and make the following
control settings which hold throughout the process of hum
adJustment: INPUT
SELECTOR at STEREO, FOCUS control at 0,
trol at 10)' both TREBLE controls at -5, both BASS controls
at 0; the two speaker systems must be in phase
near one another for this
-=8
2 - PHONO RECEPTACLE
STRIP
cord of the HF-
A convenience recep-
, with a
117VAC power to the associated
SELECTOR at PHONO, FUNCTION
LEVEL con-
and placed
adJustment. Next, procede
FIG. 4
d) TAPE OUTPUT 1, TAPE OUTPUT 2: When no
amplifier is used in the system,
available for feeding out to a stereo recorder. When an
external power ampl ifier is used in the system,
PUT 2 is used to feed out to
the external power amplifier.
If it is desired to do stereo
conditions, construct a device such as
both these outputs are
recording under the latter
shown in Fig. 4.
external
TAPE OUT-
Use low capacity shielded cable for connections.
TO INPUT
OF STEREO
RECORDER
6 ,
TO INPUT 2
OF STEREO
RECORDER
TO EXTERNAL
POWER AMPLIFIER
follows: With your ear held close to the speakers, insert
the amplifier power plug into the wall outlet and listen
to the hum level. Now pull out the plug and re-insert it
with the prongs reversed. Choose the prong position with
the least hum. Now connect the tuner input connector to
the amplifier input jack, and with the tuner set
stations and the tuner volume control set at a minimum, do
between
the same with the power plug of the tuner; use either the
117VAC receptacle on the HF-
cube tap inserted in the 117V AC receptacle on the HF-
Next)' connect the phono cartridge leads to the MAG.
PHONO 1 and 2 inputs, and, with turntable
up arm at the rest position, find the insertion position of
the turntable line cord plug that yields lowest hum. Fin-
81 or one receptacle of a
off and pick-
ally, connect the tape head leads to the TAPE HEAD
and 2 inputs, and, with the tape deck turned
insertion position of the tape deck line cord plug that
sults in lowest
just the hum balance control on top of the amplifier chassis
for least hum.
hum. When
all of this is completed, ad-
offl find the
81.
re-
operation
PRELIMINARY: Be sure all tubes are
sockets and that the tube shields are making good contact
firmly seated in their
with their baSes. As initial adjustments, set these controls
as follows: LEVEL at 0, FOCUS at
at O. Turn the amplifier on by turning the
trol clockwise from AC OFF and set it at zero
Also set the
TREBLE 1 control
0)' both BASS controls
TREBLE 2 con-
initially.
at zero. Please note that
in the instructions that follow, it is assumed that a stereo
pick-
up and/or a stereo tape head is being
the system.
LISTEN IN G TO
TOR to PHONO if you
PHONOGRAPH: Set the IN
have a megnetic cartridge or a
employed in
PUT SELEC-
ceramic cartridge with adaptors interposed between the
cartridge outputs and the MAG. PHONO
(The RIAA equalization provided at the PHONOposition
is now the international standard in the recording industry
for both monophonic and stereophonic records and is also
a very good compromise for the most important of
monophonic recording characteristics.
SELECTOR to AUX Aor AUX B if you are using a stereo-
1 and 2 inputs.
) Set
the INPUT
the older
phonic crystal cartridge (Ronette) connected to eitherAUX
A or AUX B inputs. Set the FUNCTION
either STEREO position.
channels, playa conventional monophonic
To balance levels between the
cording on the changer or turntable and turn the
control up until you have
that the action of the
normal listening level.
FOCUS control (sometimes called a
SELECTOR at
(lateral) re-
LEVEL
Note
balance" control) is to simultaneously raise the level in
one channel while lowering the level in the other as it is
turned in anyone
FOCUS control)' equal sound volumes would
channels only if the ideal conditions of identically effi-
cient loudspeakers and identical overall gains in both
direction. At the zero
setting of the
obtain on both
channels existed. With the conventional monophonic re-
cording being played
volume from each speaker system.
, adjust the FOCUS control for equal
With the
FOCUS set-
ting properly made, any stereo recording played back will
have close to the same balance as actually exists in the
recording. The
manent adjustment in that
FOCUS control setting can be a semi-
, at any given time, the setting
per-
achieved as described above will usually be satisfactory
for tape stereo, and
may also be for broadcast
stereo, if
it means exist of adjusting for equal output levels from the
stereo broadcast rece iving equ ipment. As
a shift of the
normal FOCUS control setting may be nec-
components age,
essary. Note that there are a concentricpairofbass con-
trois, one in each channel and a concentric pair of treble
controls, one in each channel. Use the
treble controls to
of the recording from the standard recording characteristic,
as well as to
of your audio system (including room acoustics). Set the
FUNCTION SELECTOR to
REVERSE for
compensate for any audible deviation
compensate for the over-
STEREO NORMAL or STEREO
stereophonic records and to MONOPHONIC
PHON 0 for CONVENTIONAL MON OPHON IC records.
LISTENING TO TAPE DECK
(direct connection to tape
separate bass and
all characteristics
head): Set the INPUT SELECTOR to TAPE. NARTB tape
head equalization is provided in both channels for
tape speed selected with the
~nel'- One position is
for71/2and
TAPE switch on the front
15ips tapes and the
the
other for 3 3/4 ips tapes. These equalizations are the
industry standard for pre-recorded stereophon i
phonic tapes.
described in the preceding paragraph
satisfactory for this function also.
If the FOCUS' control has been set as
, it will usually be
Otherwise, it may be
set in a similar manner using a test tape or
Set the FUNCTION SELECTOR to STEREO NORMAL
REVERSE for
TUNER
TREBLE tone controls as described above.
LISTENING
ED TO AUXILIARY AI, AUXILIARY Bl
PHONIC AM BROADCAST, OR
BROADCAST: Set the
AUX.
FUNCT10N SELECTOR to MO~OPHONIC
Use the BASS and TREBLE controls as described previous
LISTENING TO A STEREOPHONIC SOURCE CONNECT-
ED TO AUXILIARY Al and
stereophonic tapes or to
, AUX for
monophonic tapes. Use the BASS
TOAMONOPHONIC
, AM-FM, or FM-
SOURCE CONNECT-
TO MONOPHONIC FM
INPUT SELECTOR to AUX. A,
MUL TI.
A2, AUXILIARY B1 and B2,
respectively and the
AM and FM, FM and FM MULTIPLEX: Set the INPUT
SELECTOR to AUX A,
respectively. Set the
AUX B, AM-FM, or FM-MUL TI
FUNCTION SELECTOR
NORMAL or STEREO REVERSE. The FOCUS, BASS and
TREBLE controls are set as described previously.
MAKING
by connecting the recorder to the
See "TAPE OUTPUT 1,
TRICAL INSTALLATION. Please
cannot be made on tape decks
RECORDINGS: Tape recordings may be made
TAPE OUTPUT jacks.
TAPE OUTPUT 2" under ELEC-
note that recordings
unless those decks are
c and mono-
simply by ear.
MONOPHONIC
and
, TO
MONO-
TUNER, AUX.
at STEREO
I y.
equipped with the electronics required for recording.
FUNCTION SELECTOR: The STEREO NORMAL and STER-
EO REVERSE positions
production. At the
are both used for stereophonic re-
STEREO REVERSE
position, the chan-
nel 1 and channel 2 amplifiers from the tone controls to
the speaker connections are interchanged.
These two
positions permit interchanging the signals fed to the two
speakers so that the correct
orchestra can be achieved on all recordings or broadcasts.
The CHECK AMPL. 1 and CHECK AMPL. 2 positions per-
mit hearing either channell alone or
comparison or balancing purposes during stereophoni
left to right display of the
channel 2 alone for
c use.
The MONOPHONIC TUNER, AUX position is used for
monophonic FM, AM, tv
ridge monophonic pre-
nel 1 inputs. At this
are unused in this type of operation, are disconnected
from t
he active channel so that they cannot
interference. At the MONOPHONIC PHONO
the channell and 2
is useful when playing monophonic records with
phonic cartridge to cancel vertical rumble
sound)' monophonic phono
amplified tape etc., fed into chan-
position)' the channel 2 inputs which
contribute
position,
corresponding inputs are mixed
, which
a stereo-
components.
cart-
BASS CONTROL 1,
The plus sign on the right side of the dial indicates that
clockwise rotation from the mid-
increases (boosts) _
side indicates that counter-
BASS CONTROL 2 (CONCENTRIC):
point (0) of either control
bas~ response; the minus sign on the
clockwise rotation from the
left
mid-point decreases (cuts) bass response. There is no in-
teraction with the
TREBLE
control.
with this control set at the mid-
the "flat" position since bass response
Start all adjustments
point (0), which is called
is neither cut nor
boosted at this position.
maintenance
TREBLE CONTROL
TRIC): The plus sign on the right side of the
that clockwise rotation from the mid-
1, TREBLE CONTROL 2
(CONCEN-
dial indicates
point (0) of either
control increases (boosts) treble response; the
indicates that counter-
point decreases (cuts) treble
action with the
this control set at the mid-
flat" position since treble response
BASS control.
clockwise rotation from the mid-
response. There is no inter-
Start all
point (0), whi ch
adjustments with
is called the
is neither cut nor
boosted at this position.
minus sign
GENERAL
Your amplifiershou Id require I ittle
mal tube replacement. We
recommend no substitutions for
service except for nor-
the tube types used in this amplifier except as stated. All
the tube types used are distributed national Iy, but
ments can be obtained directly
To facil itateservicing, remedial and trouble-
cedures have been provided in the TROUBLE-
CHART that follows.
CHART is also provided
A VOLTAGE AND
from EICO if desired.
as an aid in
locating defective
replace-
shooting pro-
SHOOTING
RESISTANCE
components. DC operating voltages are given both at no
signal and signal developing 14 watts
output, as well as
the corresponding 1 kc signal voltages.
TROUBLE-SHOOTING PROCEDURES
Connect the leads from the
two speakers to the amplifier.
as described in the section "
stereo cartridge and from the
These connections are made
Electrical Connections "
the Input Selector control at PHONOand the Function Se-
lector at
STEREO. Playa known high quality stereo
record-
ing on the phonograph. If there is no output to the speaker
of if the output is
low or audibly distorted
checks for those symptoms. If there is
. the output
ampl ifier and short the phono input
, disconnect the phono input cable
hum disappears, the trouble is not
, procede to the
excessive hum in
from the
jack to chassis. If the
in the amplif.er but in
the phonograph or in the connection to the amplifier.
each case, check for the trouble in the amplifier which
seems defective. If both
the power supply.
The cause of phonograph hum may be a
not grounded to the cable shield (try a good single ground
amplifiers are defective, check
metal pick-up arm
connection to the cable shield from turntable frame, pick-
up arm, and cartridge case), direct
hum pick-up by the
magnetic cartridge from the record player motor(tryusing
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
moving phonograph away from suspected source). Check
also that the phono input cable shielding is
the ampl !fier chassis at one point only, through
of the input connector where it
Finally, try a good building ground
field in the vicinity
grounded to
the skirt
plugs into the ampl ifier.
such as a connection
from a cold water pipe terminated under speaker terminal
. Set
(try
G" on the amplifier
to other
components in the system
channel be connected to the amplifier
shielded cable to the ampl ifier
that the ground leads on both cables not be
gether at any point
ever, with some
this. In this case, just disregard this last instruction.
Excessive hum on other inputs may be checked in
Do not connect such a ground wire
If possible, let each
using a separate
input. It is
- not even at the cartridge. How-
cartridges, it will not be possible to do
also desirable
connected to-
a similar
manner. Disconnect the input cable in question and short
the particular input jack to the chassis. If the hum dis-
appears, the trouble is external to the amp!
that on all
nect to the ampl ifier only
connector. The cause and remedies for the following
symptoms are then based on the
inputs, the braid of th;;; input cable shou Id con-
through the skirt of the input
assumption that checks
ifier.
Note
made in the manner described above have eliminated the
possibilityof the trouble being external to the amplifier.
If the trouble is no output or low output
, check AC signal
voltages and DC operating voltages starting at the input
and work step_
fier. Set the
FOCUS, BASS and
(0), the INPUT SELECTOR to PHONO and
TION SELECTOR
wave signal
Square Wave Audio Generator In addition, use a pre-
cision 100: 1 attenuator to permit obtaining a
0035 volt fed into MAG. PHONO
erator output of 0.
onthelowestACvolts range ofyourVTVM
signal to hum from generator). Use a high
ance VTVM for all
VTVM or 20,
. If the trouble
replacement, signal tracing, or procede
tage and resistance measurements.
When the defective stage is local ized, procede
by-step toward the output in each ampl i-
VOLUME control to
TREBLE controls
to STEREO
, such as supplied by the EICO 377 Sine &
maximum (10), the
to their mid-points
the FUNC-
. Use a 1000cycle sine-
level of
from an audio gen-
35 volts, which can easily be measured
(also improves
input imped-
AC signal voltage
OOOQ/v
YOM
for DC volts measurements.
measurements; a
is an excessively distorted output, try tube
directly to vol-
to a resist-
ance and voltage check of the stage, using the data in the
VOLTAGE and
RESISTANCE chart.
Disconnect theampli-
fier from the power line and discharge capacitors prior to
making any resistance check and prior to removing any or
all of theEL84output tubes.
with any of the output tubes
Do not turn the amplifier on
remove
CHECKING A
1. Check tube.
2. Check plate and cathode resistor.
3. Check
4. For output stage, check dc
TYPICAL TUBE STAGE
coupl ing capacitors for leakage or short.
resistance of transformer
windings.
5. Check grid leak resistor for open.
6. Check cathode
7. If
no or
path for open or defective R60,
by-pass capacitors for short.
low B+ voltage on tube, check decoupling
R61, R62, R63 and fiI ter
capacitor C37, C38 or C39.
8. . If wiring and circuit
check O. K. and B+
coupl ing path for short or
Suspected trouble in the
volume controls and networks should lead to specific
components including the tube
voltage is
excessive)' check the de-
defective R60, R61,
R62and R63.
equalization)' tone, focus, and
re-
sistance and capacitance checks to localize the trouble.
In general, if the user suspects poor frequency response,
defective equal ization)' or defective operation of the tone
controls, the amplifier should be tested thoroughly
audio generator, vtvm, and scope.
with
SPEAKER PHASING
IMPORTANT NOTE ON
loudspeaker systems must be
in phase, meaning that corresponding cones or diaphragms
SPEAKER PHASING:
connected so that they operate.
in the systems move in and out together when
The two
actuated by
the same or similar signals. A simple method of checking
this is to playa conventional monophonic (lateral)
record-
ing having considerable bass program material, setting the
FUNCTION SELECTOR at MONAURAL. After listening
for a few minutes, reverse the connections of the speaker
leads at only one of the speaker
systems - not both
- and
listen again to the same program material. Normally, you
wi II noti ce that one of these connections seems to give
bass re-inforcement and the other bass cancellation. The
connection that gives bass re-inforcement is the in-phase
connection and should be used.
Another criterion for the in-phase connection is that of
blending, which can be best applied if the speaker
are identical or at
frequency range reproducers. With the in-
least have similar middle
nection and both speakers operating at approximately the
same volume level, a monophonic
emanating from a point mid-
speakers will blend. With the out-of-
source will appear to be
way between and the two
phase connection,
systems
and high
phase con-
the two sources will appear to remain separate.
SERVICE
If trouble developes in your instrument which
remedy yourself, write to our service
all possible indications that might be helpful.
you can;.,t
department listing
If desired
you may return the instrument to our factory where it wi
be placed in operating condition for $12.
of parts replaced due to their being damaged in the
of construction.
sure all parts are securely
instrument, giving your home address and the trouble with
the unit. Pack very carefully in a rugged
NOTE: Before returning .
mounted. Attach a tag to the
ing sufficient packing material (cotton,
50 plus the cost
course
this unit, be
container)' us-
shredded news-
paper, or excelsior), to make the unit completely immov-
able within the container.
is satisfactory, providing the original
sufficient packing material
ment immovable.
possible, to Electronic Instrument Co.,
ern Blvd., Long Island City I,
mentwill be made byexpress collect. Note that a
Ship by prepaid Railway
cannot be held liable for
The original shipping carton
inserts are used or
inserted to keep the instru-
Express, if
Inc., 33-
New York.
00 North-
Return ship-
carrier
damages in transit if packing
IN HIS OPINION)' is insufficient.
TROUBLE-
SHOOTING CHART
SYMPTOM
Amplifier causes power line fuse to
blow. Power line
with VII &
fuse blows again
V12 out of their sockets.
Amplifier causes power line fuse to
blow. Power line fuse
again with VII &
does not blow
V12 out of their
sockets.
Any or all tube filaments not lit.
Output tube bias too high (result-
ing in distorted output waveform).
DC voltage at Vl1, V12 cathodes
(pin 3) is incorrect as specified
below.
a) No
voltage.
CAUSE
Line cord, J16, primary or high voltage
secondary windings of T1 shorted internally
or externally (wiring).
VII, V12, C39)' V7, va, V9,
T3 primary shorted internally or
VI0, or T2
exter-
nally.
Open tube fil ament.
Open lead from 6. 3V winding of T1.
6 3 V winding of T1 open.
R56, R57.
Open
Defective VII or V12.
C39 shorted internally or externally.
REMEDY
Replace or repair.
Replace or repair.
Replace or repair.
Replace or repair.
Replace
Replace or repair.
b) High voltage.
c) Low voltage.
Excessive hum on mag. phono tape
head or mic.
Excessive noise on mag. phono
tape head or mic.
Connection from C39 to pin 3 of VII
& V12 broken.
Connection to center tap of h. v. second-
ary winding of T1 open.
Output tubes V7, VS,
V9, VI0 over-
biased or not drawing current. May re-
sult from open
R56 or R57.
Excessive current drain in amplifier.
Defective VII, V12.
VI or V2 defective.
leads dressed toa close to grid
FiI.
lead.
Tube shield not making electrical con-
tact to base or base not
trical contact to chassis.
making elec-
Shielding and grounding of wiring to
input jacks not exactly as instructed
and shown in drawings.
VI and V2 and contacts dirty.
Repair
Repair
Replace, repair, or see troubleshooting typical tube stage.
See trouble-shooting typical tube
stage.
Replace
Replace
Dress fit. leads
Check and correct.
away from grid lead.
Correct
Clean throughly with carbon
tetrachloride.
Sustained oscillations.
Sustained microphonicson mag.
phono, tape head or mi c.
Hum on all inputs.
Poor dress of output transformer T2 or
T3 leads.
VI or V2 defective.
V3 or V4 defective, not properly
shielded, or dirty sockets and contacts.
Dress of power transformer T1 leads.
Dress all input leads and T3 leads
away from each other. Keep T3
leads away from input jacks.
Replace
Replace, correct
, or clean.
Correct
VOLTAGE AND RESISTANCE CHART
TUBE
CC83(12AX7
ECC83/12AX7
ECC82/12AU7
V3, V4
PIN# OPERATING VOLTS
AT NO SIGNAL
(DC UNLESS NOTED)
4&5
filament (OVDC; 6. 3VAC to pin 9)
filament
4&5
4&5
filament (OVDC; 6. 3VAC to pin 9)
fi lament
filament (OVDC; 6.
1. 8
filament
OPERATING VOLTS
AT 14W OUT
(DC UNLESS NOTED)
3VAC to pin 9)
1. 75
SIGNAL VOLTS
(1 kc) at 30W OUT UN IT DISCONNECTED
014
OHMS
FROM POWER)
290KO
IMO
7KO
500
290KO
0035
90KO
2KO
500
290KO
IMO
7KO
500
290KO
90KO
2KO
500
1. 2
. 1
120KO
61OKO
3KO
500
170KO
190KO
065
8KO
500
ECC83/12AX7
V5, V6
EL84(6BQ5
EL84(6BQ5
195
4&5
filament (OVDC; 6. 3VAC to pin 9)
filament
12.
4&5
filament (OVDC; 6. 3V AC between pins 4 & 5)
335
330
12.
4&5
filament (OVDC; 6. 3V AC between pins 4 & 5)
-,7 335
190
1. 15
1. 1
,1,
14.
325
320
14. 03*
325
180
6 2
180
100KO
470KO
100KO
500
470KO
250KO
7KO
500
340KO
340KO
1650
500
330KO
165 1900
330KO
3500
340KO
340KO
1650
500
330KO
330KO
330
320
3500
EL84/6BQ5
V9, V10
4&5
0 6.
12. 7
filament (OVDC; 6. 3VAC between pins 4 & 5)
14. 7 . 03 *
340KQ
340KQ
165Q
50 Q
EZ81/6CA4
VII, V12
All resistance measurements, except those
made with pin 3 of V11 and V12 grounded.
to chassis with the controls set as follows:
to STERO NORMAL)' LEVEL at
at 14W output
signal to the CH 1 &
load to the output of each amplifier, of equal resistance to the tap selected
handling 15 watts. Voltage measurements are made with a
voltage measurements are made is 117VAC, 60cps.
NORMALLY BY::I:15%.
335
330
290 V AC *
340 335 7.
4&5
* = 60 cycles
, set the input selector to the PHONO position
filament (340VDC; 6. 3VAC between pins 4 & 5)
290V AC *
made from pin 3 of Vl1 and V12
All voltage and resistance
INPUT SELECTOR to
10, BASS, TREBLE & FOCUS controls at O. For voltage measurements
CH 2 Mag. Phono Input jacks; connect a resistive (preferably non-
325
320
29OV AC* 290*
290V AC *
PHONO, FUNCTION SELECTOR
and feed a O. 0035volt
VTVM. Operating line voltage atwhlch
NOTE: ALL VOLTAGE &
180
290* 45-
measurements are measured
(::1:20%), and
165- 190 Q
330KQ
350Q
45-55 Q
100KQ
100KQ
(EZ81 rectifier),
(;3. 5mv) 1 kc
inductive)
capable of
RESISTANCE VALUES
55 Q
are
Loading...