Eico HF-20 User manual

HIGH FIDELITY AMPLIFI ER
MODEL
HF-20

MODEL HF20
HIGH FIDELITY AMPLIFIER
The EICO Model 20 ts the result of oprogram aimed at
bringing together In one Integrated unit the finest pre-
amplifier control, and power amplifier circuitry. Please
read the following Instructions before Installing or using
the amplifier, particularly If you are not thoroughly fa-
miliar with equipment of this type. You will learn how
to Install the amplifier properly and how the controls and
facilities should be used to obtain the best results.
You may skip over the Installation section If your ampli-
fier Is Installed by acompetent technician, but this
section contains important specific Instructions and a
mounting templatewhich should bemode available to the
person performing the Installation. In anycase. It ts Im-
portant that this manual be retained since It contains es-
sential servicing Information which will be needed by
any person who undertakes to service the amplifier.
DESCRIPTION
The Model 20cons!stsofa high quality preamp-equallzer
and control section plus a20 watt Ultra-LinearWilliam-
son type power amplifier. Details are as follows:
THE PREAMPLIFIER-EQUALIZER CIRCUIT possesses ex-
tremely low distortion due to equalization entirely by
feedback-”!! was chosen deliberately because of Its ability
to match the low-dlstortton performance of the Ultra-Lin-
ear Wllllamson-type amplifier circuit* It has abalanced
selection of equalizationswhich, together with the wide-
range bass and treble tone controls, permits correctcom-
pensatlon for practical ly any mtcrogroove or 78 recording
characteristic, foreign or domestic.
FOUR HIGH LEVEL INPUTS AND 2LOW-LEVEL INPUTS
(1 switch position) enable the *20 to accommodate TV,
tape recorder, AM-FM tuner, and crystal cartridge (or
separate AMand FM tuners), as well as any leading mag-
netic or FM pickup without the necessity of component
changes. Alow Impedance, logically-placed tape out-
put [ack ts avaluable convenience for those owning or
planning to own atape recorder.
THE BASS ANDTREBLE TONE CONTROLS are of the new
feedback type for exceptionally low distortion and wide
frequency range. Theydo not affect the volume or Inter-
act with each other—providing the easiest possible con-
trol settings. As turnover on both ends varies with the
amount of boost and attenuation, boost or cut at the ex-
tremes of the audio range Is possible without affecting the
mid-range.
THE LOUDNESS .CONTROL, aCentralab Compentrol,
raises or lowers volume In strict accordance with the ac-
cepted Fletcher-Munson ear-response curve. Operation
together with front panel level control provided Is widely
heldas oneof the most flexible and sensible arrangements.
THE POWER AMPLIFIER: The power amplifier In the *20
is of the Ultra-LinearWilliamson type. Its superb perform-
ance characteristics are augmented by the high-quality
output transformer, which Is conservatively rated at 25
watts. SPECIFICATIONS
Power Output: 20 watts (34 watts peak)
IM Distortion (60 &6000 cps/4: 1, 20 W):1. 3%
Mid-Band Harmonic Distortion (20W): 0.3%
Power Response (20W) +0, *1 db 20 to 20,000cps
+0, “3 db 10 to 40,000 cps
Frequency Response (1/4W):+0,-1 db 13*35,000 cps
+0, “3 db 7"50,000cps
Damping Factor:7:1
Inverse Feedback: 14 db
Speaker Connection Taos:4, 8, and 16 ohms
Tone Controls: Bass: 15db boost or cut at 50cp?
Treble: 15db boostor cut at lOkc
Phono Equalizations:RIAA, Columbia, London, Euro-
pean 78, American 78.
Sensitivity:Mag. Phono 0. 004 Vrms (atl kc)
for 20W output
Tuner, etc.—-0*4 Vrms for 20Woutput
*Hum &Noise: Mag. Phono** —60 db below 20W
Tuner, etc. __75db below 20W
** Includes 16 db boost at 60 cps due to RIAA compensation.
*Maximum gain and tone controls set at flat positions.
«
i
Power Une Requirement 1Q5~125 volts, 50/60cm AC
only
Power Consumptions 1 00 watts
Size; 81/2" high, 15" wide, 10" deep
Weights 24 lbs.
INSTALLATION
1.GENERAL FACTORS
a) HEAT DISSIPATION (VENTILATION): In common
with other electronic equipment, the Model 20 produces
agreat deal of heat in normal operation. Unless contin-
uous and adequate air flow ts obtained around the heat
producing elements, these elements will over-heatand
their useful life will be greatly curtailed.

i* buseful to understand the process of convectionwhere-
'by heat Is removed In fudging the suitability ofalocation.
Air heated by the heat-producing elements expands and
rises; cool air Is drawn from beneath to take the place of
the heated air. In this manner, astream of atr Is set In
motion which continually removes heat from the ampli-
fier. (In particular, we are mainly concerned with the
mafor heat-producing elements; the two 6L6GB output
tubes and the 5U4GB rectifier tube.) If there Is any Im-
pediment to or constriction of the air flow, the essential
process of heat removal will be adversely affected.
Adequate venttlatlon will be provided If the amplifier Is
Installed In an open-back console provided that the top
of the amplifier ts spaced at least two Inches below any
shelf mounted above It. If the cabinet ts enclosed at the
rear, provide several large holes or slots as low down and
as high up In the cabinet back as possible. As an alter-
nate, holes may be provided In the sides, bottom, or top
of the cabinet. The Important thing to remember Is that
effective ventilation requires provision for cool atr to en-
ter at the bottom and hot air to leave at the top.
If the amplifier ts not Installed In aconsole. It should be
situated preferably on an open surface, not on ashelf of
abookcase. An attractively finished matching cover for
the Model 20 Is available which will provide a"finished11
appearance as well as protection when the amplifier Is
not Installed In aconsole. Four rubber feet are also pro-
vided 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 aheight which will permit easy manipulation of the
controls. Tuner controls should be located nearby.
c) ACCESSIBILITY TO PARTS: Tubes are the most fre-
quently replaced Items In electronic equipment. If the
amplifier ts Installed tna console, sufficient space should
be alloted to reach and remove any tube In the amplifier.
Furthermore, Input and output terminals of the amplifier
should be accessible to permit easy interchanging of sys-
tem components for comparlsonjand connection or discon-
nection of aportable tape recorder which Is stored away
when not In use. If antennas are strung around the back
of the consoletn which the amplifier is Installed, arrange
them so they will not Interfere with access to the amplifier.
d) ACOUSTICAL ISOLATION: If amplifier and speaker
are installed In the same cabinet (not recomemnded), pro-
vide sufficient separation to minimize mechanical speaker
vibration reaching theampllfler. The minimum separation
Is about one foot.
1. CHASSIS MOUNTING IN CONSOLE
a) Operation, on contole front panel preliminary to am-
plifier mounting—
-
M)Tape the panel template provided
to the face of the console so that the top of the mounting
surface line on the template Is level with the top of the
amplifier mounting shelf. (2) Use an awl or anail to
.•4
4
pierce the centers of the five 5/9" diameter holes for the
controls and the two small holes for mounting the control
plate, to transfer their locations 'to the console panel be-
neath. (3) Remove the panel template. (4) Drill the
holes for the panel controls only (the two small holes which
have been marked are for wood screws).
b) Amplifier mounting In console: (1) Pull off the con-
trol knobs (a second set of knobs with long shanks has
been provided for console Installation). (2) Remove the
control plate, which Is attached to the chassis apron by
two screws. (These may be discarded since they are un-
suitable for attaching the control plat, to the console
panel and two^4 X3/Bwood screws have been supplied
for this purpose.) (3) Fasten the control plate to the con-
sole panel with the 2^4 X3/3 wood screws. (4) If the
rubber feet have been Inserted In the bottom plate, re-
move them. (They may be pried out with athin screw-
driver.) (5) Place the unit on the mounting shelf and
slide It as far forward as possible, so that the controls
penetrate the panel holesas far as possible. (6). Place
along shank knob on each control, pressing each knob
toward the chants firmly so that each control shaft enters
fully Into Its knob. (7) Draw the chanls back evenly
and carefully until the back rims of all the knobs are
equally spaced from the control plate about 1/8". (B)
With asharp pencil, placed with Its point directly against
the edge of the lower surface of the bottom plate, draw
the outline of the bottom plate on the chanls shelf. (9)
New remove the knobs and take the chants off the shelf.
(10) Remove the 8screws which fasten the bottom plate
to the chanls. (11) Place the bottom plate exactly In
theoutllnedrawn on the shelf (bumps facing up) and marie
the positions of the two holes on the left side and the
two holes on the right side. (12) Remove the bottom
plate and drill each of the marked holes on the shelf to
adiameter of 1/4". (13) Refasten the bottom plate to
the chanls, with the 4*8 X3/B screws prevlousljiip-
moved, using the 2holes at the rear and the 2horns at
the front of the chanls. (14) Replace the chassis on the
shelf, positioning It exactly In the outline previously
drawn, and restore the knobs. This time make sure that
the Indicator dot on each knob agrees with the control
position. (15) From the bottom side of the shelf. Insert
a*8 X1" screw with a1/2" flat washer against the head
through each of the four left and right side holes.. These
screws engage the stamped nut over each hole on the
chanls flange and when tightened secure the chanls to
the shelf.
2. ELECTRICAL CONNECTIONS
a) SPEAKER CONNECTIONS: To connect your speaker
to the amplifier' properly, you must know Its rated Im-
pedance. This may be read off the speaker nameplate.
Connectone speaker lead to the terminal on the rear apron
marked nG"and the otherspeaker lead to the nearby ter-
minal designated by the rated speaker Impedance (4, 8,
or 16 ohms). Plastic-covered lamp cord may be used for
distances up to 50 ft. with little power Ion. For shorter
distances, TV antenna lead can be used, particularly If
It Is desired to run the speaker lead under arug.

If It It detlred to use two similar or Identical full-range
speakenof the tame rated Impedance (either 8or 16 ohms
only) for better sound distribution, connect one speaker
lead of each pair to "G" and the two remaining leads to
the terminal with anumber equal to half of one of the
speaker's rated Impedance.( It maybe necessary to "phase"
the two speakers by reversing both of the leads from one
of the speakers.) This may not be done If each of the
speakers Is designed for reproduction of adifferent part
of the audio spectrum (woofer-tweeter combinations) In
which case across-over network Is required which con-
nects to the amplifier with only one pair of leads.
b) PHONO INPUT: The shielded lead from your phono-
graph should be provided with ashielded "phono-type"
plug. The Input (aek on the amplifier Into which this
plug should be Inserted depends on the type of cartridge
employed. Specific Instructions follow
GE Variable Reluctance or Professional, Pickering, Fair-
child, Recoton, Electrosonic &transformer: Connect to
PHONO INPUT 1
.
Weathers FM Capacitance pickup:
Alternative 1—Use Weathers Adaptor PlugModel P'631
and connect PHONO INPUT 2.
Alternative 2—Cut the Jumper shorting the 47mmfcapa-
citor comingoff PHONO INPUT 1fack Inside the chassis
(Identified by red tape In wired units). Connect from the
"constant amplitude” output of the Weathers oscillator
unit to PHONO INPUT 1
.
Audak, Ronette TO-284P; Ferranti &transformer: Con-
nect to PHONO INPUT 2.
Ceramic or crystal cartridges that equalize for RIAA curve.
Use Electro-Voice Adaptor Model 504 and connect to
PHONO INPUT 2.
If an adaptor such as the Electro-Voice Model 504 Is not
used, acrystal or ceramic cartridge may be connected to
the AUX. INPUT. The equalizer-preamplifier circuit Is
not effective In this case.
e) HIGH LEVEL INPUTS—Four high level Input |acks
designated as Tuner, TV, Tape, and Auxiliary are pro-
vided for connectlonof tuners, tv receivers, tape recorder
playback, andordinaryor RIAA equalizing crystal or cera-
mic phono cartridges without adaptor. Ashielded cable
with ashielded "phono-type" plug should be used to con-
nect each'of these sources to the corresponding amplifier
Input jack. Unless the source has alow—Impedance out-
put such as acathode fol lower (with which up to 50 ft. of
cable can be used), use the shortest possible connection
ana low, capacity shielded cable (cable having as low as
25mmfd capacitance per foot Is available).
If the tuner employed has avolume control to adjust the
output, set this control as follows. Turn the amplifier
LEVEL control to minimum and the LOUDNESS control to
maximum.Playany record!ng on your phonograph and turn
up the level control to obtain on ordinary listening level.
Without touching the LEVELor LOUDNESS controls, turn
the SELECTOR to TUNER and ad|ust the volume control
on the tuner to obtain approximately the same loudness
level as was obtained from the recording. In the case
where the tuner has no output level control and also In the
case of theotherhlgh level Inputs, the Independent LEVEL
control on the front panel of the amplifier permits adjust-
ment of the level when changing Inputs.
c) TAPE OUTPUT: Ashielded cable (up to 30 ft. may be
used) wlthashtelded "phono-type" plug should be used to
connect from the TAPE OUTPUT jack to the Input of the
tape recorder. Any Input chosen by the SELECTOR Is fed
out to the tape recorder through this jack. Phono Inputs
fed In at PHONO INPUT 1and PHONO INPUT 2are of
course equalized according to the equalization selected
andall Inputs are affected by the level and tone controls.
The loudness control does not affect the tape output and
permits adfustmentof the listening level while recording.
d) POWER CONNECTIONS: The power cord of the
turntable and tuner may be Inserted In the convenience
outlets provided mi the rearchassis apron. Thereeeptaele
marked "PHONO*9provides 110 volts AC regardless of
whether the power switch of the amplifier Is turned on or
off In order to protect the turntable mechanism .The
receptacle marked "TUNER" ts "live" or "dead" depend-
ing on whether theamplifler power switch Is turned on or
off.
3. HUM ADJUSTMENT
a) After checking the amplifier for proper operation,
remove all Input cables to the amplifier and make the
fol lowing control settings which hold throughout the pro-
cess of hum adjustment: SELECTOR at RIAA, LEVEL &
LOUDNESS to 10, TREBLE control at "5, BASS control
at 0. Next precede as fol lows: With your ear held close
to the speaker, Insert the amplifier power plug Into the
wall outlet and listen to the hum level. Now pull out
the plug an re-Insert It with the prongs reversed and listen
again. Choose the prong position which gives the least
hum. Now connect the tuner Inputconnector to the am-
plifier TUNER Input jack, and with toner set between
stations and the toner volume control set at minimum, do
the same with the power plug of the toner, using the
TUNER convenience outlet on the amplifier If desired.
Finallyconnect the phono Input connector to theamplifler
PHONO 1or PHONO 2Input as Is required (turntable
off and pickup arm at rest position) and do the same with
the power plug of the turntable, using the PHONO con-
venience outlet on the amplifier If desired. When ail of
this Is completed, adjust the hum balance control on top
of the amplifier chassis for least hum.

PRELIMINARY! Be lure oil tube* are firmlyseated In their
sockets and that the tube shteldsare making good contact
with their bases. As Initial adjustments, set these controls
as follows: LEVEL at zero,LOUDNESS at ten, BASS at
zero. Turn the amplifier on by turning the TREBLE con-
trol clockwise from OFF and set It at zero Initially.
LISTENING TO PHONOGRAPH: Set the SELECTOR to
oneof the record equalization positions on the dial. Do-
ing so automaticallyselects thephonograph Input plugged
Into PHONO INPUT 1or PHONO INPUT 2. For help
In choosing the recording curve appropriate to any parti-
cular record, refer to thechart titled "RECORD EQUILh
ZATION SELECTION". When In doubtas to which equl II-
zaflon Is most appropriate, use RIAA, which Is the best
compromise for all records. Keep In mind that while the
positions offered caver most recording curves likely to be
encountered, additional separate and variable bass and
treble response adjustments are necessary for folly satis-
factory results. These may be necessary to compensate
for the over-all characteristics of your audio system (In-
cluding room acoustics). Inexact matching of the actual
recording characteristic by anyof the equalizations pro-
vided, and, aboveall, the particular tastes of the listener.
4
LEVEL &LOUDNESS CONTROLS: Simply stated, the
purpose of the LOUDNESS control Is to provide compen-
sation for the Increasing Inefflctencyof the human ear In
hearing bass and treble withdecreasingvolume level .The
LOUDNESS control, as It Is turned counter-clockwise
from maximum clockwise rotation, not only decreraes the
volume but Increasingly emphasizes the bass and treble
according to the Fletcher-Munsoncurves (curves developed
from astatistical study ofthis effect). An uncompensated
LEVEL control Is also provided to "set" the LOUDNESS
control for proper operation In any system, and also for
the purpose of adjusting the listening level when going
from quiet program material to loud program material or
the reverse without occasioning achange In the loudness
compensation. To "set" the LOUDNESS control at any
time, perform these operations In the order gjv^p to avoid
blasting or possibledamage to speakers of low power-hand-
ling capacity: a) Turn the LEVEL control to zero; b)
Turn the LOUDNESS control to ten; c) With high level
orchestral program material being fed to the amplifier from
your phonograph or tuner, advance the LEVEL control set-
ting until arelatively loud listening level Is obtained,
d) Turn down the LOUDNESS control until your normal
listening level Is obtained with the LEVEL control set as
just described. Proper loudness compensation should now
be obtained at any listening level adjusted to with the
LOUDNESS control .The same reference LEVEL control
setting will be suitable for both phonograph and tuner list-
ening If the volume control of the tuner has been adjusted
as described In the "High Level Inputs" sub-section of the
"Electrical Connections" section. When selecting Inputs
which do not have level ad|usts, such as tv or acrystal
cartridge connected to the AUX. Input, It may be desir-
able to set the LEVEL control to zero beforehand and then
bring up the LEVEL control to obtain the desired list-
ening level to avoid blasting. Note that the LEVEL con-
trols affects the output to tape recorder available at the
TAPE OUT jack but that the LOUDNESS control has no
affect on this output.
BASS CONTROL: The plus sign on the right side of the
dial Indicates that clockwise rotation from the mid-point
(0) Increases (boosts) ban response; the minus sign on the
left side Indicate that counter-clockwtse rotation from the
mld-potnt decreases (cuts) ban response. There Is no In-
teraction with the TREBLE control. Start all adjustments
with this control set at the mid-point (0^which Is called
the "flat" position since ban response Is neither cut nor
boosted at this setting. This control does affect theout-
put to atape recorder from the TAPE OUT jack to permit
"touching up" of the record equalization or reducing the
effect of low frequency disturbances when recording on
tape. Set It at zero If no effect during recording Is de-
sired.
e
TREBLE CONTROL: The plus sign on the right side ofthe
dial indicates that clockwise rotation from the mid-point
(0) Increases (boosts) treble response; the minus sign on
the left side Indicates that counter-clockwise rotation
from »hs mid-pointdecreases (cuts) treble response. There
Is no Interaction with the BASS control. Start all adjust-
ments with this control set at the mtd-potnt (0),
which Is
called the "flat" position since treble response Is neither
cut nor boosted at this position. This control does affect
the output to atape recorder from the TAPE OUT jack to
permit "touching up" of the record equalization or reduc-
ing the effectof high frequency disturbances when record-
ing to tape. Set It at zero If ho effect during recording Is
desired.
LISTENING TO TUNERS, TV, TAPE RECORDERS: With
the SELECTOR switch set at TUNER, TV, TAPE or AUX-
ILIARY, the corresponding high level Input from aradio
tuner, tv, tape recorder, second tuner or crystal cartridge
will feed through the amplifier. Adjustmentof the volume
control on eachsource Is discussed In the "Electrical Con-
nections" section under "High Level Inputs” and again
under "Lever &Loudness Control" In this section.
MAKING RECORDINGS: Tape, wire, or disc recordings
'"ay be made by connecting the recorder to the TAPE
OUTPUT jack. See "TAPE OUTPUT" under ELECTRICAL
CONNECTIONS" and the "BASS CONTROL" and "TRE-
BLE CONTROL” operating Instructions. With the output
of the recorder connected to the "TAPE INPUT" jack,
turning the SELECTOR switch to TAPE readies the ampli-
fier for playback of the recording.
RECORD EQUALIZATION SELECTION
Recordsare made with boosted volume In the treble range
to mask surface noise and reduced volume In the bass
range to conserve groove space and reduce distortion.
As there was no universally accepted standard of treble
boost and bass cut In recording before Spring 1954, re-
cords of which the masters were made before this date
may require any one of several different equalizations

(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 companiesand 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
Capital-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
acareful, stage-by-stage check of the operation.

TROUBLE SHOOTING CHART
SYMPTOM CAUSE REMEDY
Amplifier causes power line
fuse to blow. Line cord, J8, J9, primary or high voltage
secondary windings of Tl, Incorrectly wired.
Prt./h.v. sec. windings of Tl shorted.
(If the amplifier causes the line fuse to blow
again when connected to the line with 5U4 GB
rectifier V7 removed, one or the other of the
above causes must be the reason.)
V7 shorted replace after checking C26
V7 filament not lit. Incorrect wiring of fll. leads to V7 socket. repair
5V fll. winding of Tl open. replace Tl
Any or all other tube filament Open lead from 6.3 Vwinding of Tl
.
repair
not lit. 6.3 Vwinding of Tl open. replace Tl
DC voltage at V7 cathode
(pin 8) Is Incorrect as specified
below.
*
*
a) No voltage Defective V7 replace
C26 Ashorted Internally or externally. replace or repair
b) High Voltage Connection to C26 Afrom pin 8of V7 broken. irepair
Connection to center tap of h. v. sec. winding
of Tl open. repair
Output tubes V5 &V6 over-biased or not draw-
Ing current.
see trouble-shooting typical i
c) Low voltage Excessive current drain In amplifier. see trouble-shooting typical j
Defective V7. replace
Connect aphonograph and speaker to the amplifier as described In "Electrical Connections" and set controls for phono list-
ening. Play aknown high quality LP recording on the phonograph. If there Is no output to the speaker or If the output Is
low or audiblydistorted, procede to the checks for those symptoms. If there Is excessive hum In the output, disconnect the
phono Input cable from the amplifier and short the phono Input |ack to chassis. If the hum disappears the trouble Is not In
the amplifier but In the phonograph or In the connection to the amplifier.
The cause of phonograph hum may be ametal pick-up arm not grounded to the cable shield (try agood single ground con-
nection to the cable shield from turntable frame, pick-up arm,and cartridge case), direct hum pick-up by the magnetic car-
tridge from the record player motor (try using arubber mat on the turntable to Increase the separation of the pick-up from
the motor), or pick-up from apower transformer or other magnetic field In the vicinity (try moving phonograph away from
suspected source)* Check also that the phono Input cable shielding Is grounded to the amplifier chassis at one point only
through the skirt of the Input connector where It plugs Into the amplifier. Finally, try agood building ground such as a
connection^from acold water ptpo terminated under speaker terminal "G" on the amplifier. Do not connect such aground
wire to other components In the system.
Excessive hum on other Inputs may be checked In asimilar manner. Disconnect the Input cable In question and short the
pwtlcular Input fack to the chassis. If the hum disappears, the trouble Is external to the amplifier. Note that on all Inputs,
the braid of the Input cable should connect to the amplifier only through the skirt of the Input connector. The cause and
remedies for the following symptoms are then based on the assumption that checks made In the manner described above have
eliminated the possibility of the trouble being external to the amplifier.

GENERAL INSTRUCTIONS
Core token tn the construction of this Instrument will reword the constructor
wlthmony years ofsatisfactory service and greater confidence In his Instrument,
Weurge you to not rush the construction, but to takeal) the time necessary for
proper, assembly and wiring.
Furthermore, we urge strongly that you follow the wire and parts layout shown
in the pictorial diagrams as closely as possible. This Is essential, because the
position of wires and parts is quite critical in this instrument; changes may
seriously affect the characteristics of the circuit.
UNPACKING THE KIT: Unpack the kttcarefullyand check each part against
the parts list Including those parts that are mounted to the chassis. If you have
trouble identifying any parts, refer to the pictorial diagrams or the color code
chart.
You may find that the value of acomponent will vary within the allowable
circuit tolerance. As an ©Sample, a470K ohm resistor may have substituted
for it a510K ohm resistor if the circuit is such as to allow this substitution.
In general, resistors and controls have atolerance of ±20% unless otherwise
specified. Therefore a100K resistor may measure anywhere between 80K and
120K ohms. Tolerances on capacitors are even greater, unless specified.
Limits of +100% and "50% are usual for electrolytic capacitors.
CONSTRUCTION HINTS: USE THE BEST GRADE OF ROSIN CORE SOLDER
ONLY, preferably one containing the new activated flexes such as Kester
"Resin-Five", Ersin "Multicore" or similar types. UNDER NO CIRCUMSTAN-
CES USE ACID CORE SOLDER OR ACID FLUX since acid flux can cause se—
rious corrosion. Before soldering make certain of agood mechanical connec-
tion. Use aclean, freshly tinned soldering iron, no smaller than 100 watts,
and place the solder on the joint (not on the iron) so that the solder is melted
by the heat from the joint itself. Do not remove the soldering Iron until the
solder flows and check to see that the resulting joint is smooth and shiny
when the solder has cooled. There are two extremes to be avoided; too little
heat and too much heat. If too little heat is applied, the joint will appear
pitted and grey. Indicating arosin joint which is unsatisfactory. On the other
hand, if too much heat is applied to ajoint, the parts connected to it may
either change value, lose their protective coating, or break down. If you are
soldering close to apart, hold the lead between the pprt and the joint being
soldered with the tip of apair of longnose pliers. The pliers will conduct the
heat away and prevent the component from being unduly overheated. If for
any reason it is necessary to resolder ajoint, be sure to use new solder.
It should also be noted that the leads on transformers, capacitors, and resistors
are very often longer than necessary. These leads should be trimmed to the
proper length when wiring.
CONSTRUCTION PROCEDURE:The complete step-by-step mounting and
wiring procedure follows. To keep the drawings uncrowded, unnecessary rep-
etition ofmounting or wiring details may be omitted. Note: The abbreviation
(C) means connect but do not solder (until other leads have been connected).
The abbreviation (S) means connect and solder.
The drawings belowshow the method ofmounting certain specific components
properly. Solder lugs are shown In the socket mounting drawings simply to
Indicate the correct position ofsuch alug when it Is specified for aparticular
socket. The mounting drawing for the hum-balancing pot R33, which must
be Insulated from the chassis, shows the proper position of the Insulating shoulder
washer. Refer to the relevant drawing as required during the mounting pro-
cedure. INSERT DRAWINGS -FOR FIG. 1

MAIN chassis assembly
il fl-An 'Moul*°c #k Ahwlth *N®ld iupports XVI &XV2as *hown. Use
ZASnzcz2Xt-*,~k"—--'4Z
hex nuta end too*! Mwah^u"’l”""' U“lwo
L
'4"40 *crew*. two U
strip TB9 und° 111 Mount 0one P°»* right with ground terminal
T'b™9
;
under one loekw«her at one end of socket. See insert drawina E
()F,g. 1Mount socket, XV4, as shown. Use two #4~40 k™. two #4
temfaal sTip^W4und^T^T' °***** tW°r,®ht wftb sround
()Ftp. I.' Moon', ft.7<SS
ne. on. fiber flo, wosher end ZflCiSL Be
£
TiZ Vtrt °°°!M*" Ch“*'*' *• drawing 51 **
«"d (bur <10 lockwrahea. Mount three <10
(TroT“uer *IT °f*• See insert drawing A.
JJ. Vh^isr
installed' *d Ik ^^*?*#,°,od'w«h®«- Ut* the cable clarlp
/V1,** U ,ndMhe
»
m°°nHn9 nut ,hown te 8«*«r the 4leads referred to above
“™- ?£» Pf* «>*> OnranJ
()Fia lMZt Li"I? °ne 6lockwa*her Per terminal strip.
carefuHy^the^ position oJ^ and °7'«Not.
square) next ta^l f** J?1™Code mark®" (Wangle, semi-circle and
slots in the chassis and tj*® c?Paci,or-ln,#rt tho mounting tabs into the
NOT (uiiet -t >®*ah* somewhat less than aquarter turn DO
NOTtw.st *e tab. excessively or they will shear off.
screws* *twotf^hl *?*’ ®"dXV7as shown. Use two #6-32X3/8
screws, two r6hex nuts and two '6 ioelrwntliAn
"tindl strip, 7B4, with XVd. See in.JdrJJi^E °°“ P°" ^
PRELIMINARY WIRING
()Fig. 1. Twist the two green leads from the power transformer, Tl, and
connect one lead to R33-1 (C) and the other to R33“3 (C).
()Fig. 1.Connect ayellow lead from R33“1 (S) to XV6-7 (C).
()Fig. 1.Connect abrown lead from R33“3 (S) to XV6-2 (C).
LIJ** 1:s
Cut and
t
,trip lhe en<fe of onc 5",en8»h of yellow wire and one
5length of brown wire. Connect one end of the yellow lead to XV6-7 (S)
and one end of the brown lead to XV6-2 (S). Twist the two leads. Connect
«d°ta XV5-2°(C) e^le°d *° XV5’7(C> °nd tHe OHier °nd °ffhe brown
*
()Fig. 1. Following the above procedure, cutand strip a6" length of brown
wire and a5" length of yellow wire. Connect the yellow lead to XV5“7 (S)
and the brown lead to XV5“2 (S). Twist the two leads. Connect the yellow
lead to XV4-9 (C). Pass the brown lead through XV4-5 (C) to XV4“4 (S).
( ) Fig. 1.Following the above procedure, cut and strip a3" length of yel-
low wire and a5“ length of brown wire. Connect the yellow lead toXV4“9(S)
and the brown lead to XV4“5 (S). Twist the two leads. Connect the yellow
lead to XV3-9 (C) and the brown lead through XV3“5 (C) to XV3-4 (S).
()Fig. 1.Following the above procedure, cut and strip a5" length of yel-
low wire and a5“ length of brown wire. Connect the yellow lead to XV3-9
(C) and the brown lead to XV3-5 (C). Twist the two leads. Connect the yel-
low lead to XV2“9 (S) and the brown lead through XV2“4 (S) to XV2~5 (S).
()Fig. 1.Following the above procedure, cut &strip a7" length of yel-
low wire and a7" length of brown wire. Connect the yellow lead toXV3-9(S)
and the brown lead to XV3-5 (S). Twist the two leads. Connect the yellow
lead to XV1“9 (S) and the brown lead through XV1”5 (S) to XVI ”4 (S).
LIk Tw!’L
t!,e ye,M°W,ead*of the P°wor transformer Tl and connect
to XV7-2 (S) and XV7-8 (C).
J* F!S/J- J^L**'*1,ead*of power transformer Tl and connect to
XV7-4 (S) and XV7“6 (S).
()Fig. 1. Connect the red-yellow lead and the bare lead of the power
transformer Tl to ground lug "F“ (S).
()Fig. 1.Twist the red and red-yellow leads of the output transformer T2
and connect to TBS (C).
()Fig. 1. Connect ablue lead from TB8(C) to C26“2 (C).
()Fig. 1.Twist the blue and blue-yellow leads of the output transformer T2.
Connect the blue lead to XV6“3 (S) and the blue-yellow lead to XV6“4 (S).
JJ/1®* 1
11™!** the, brown and brown-yellow leadsof the output transformer
Tl. Connect the brown leadtoXV5“3(C)and the brown-yellow lead to XV5~4(S)
()Fig. 1.Connect a611 blue lead from TB5"1 (C) to C27-3 (C).
()Rg. 1.Connect an 8Mblue lead from TB5-3 (C) to C27-4 (C).
( ) Fig. 1.Connect one end of a4“ blue lead to TB4 (C). Past the other
end thru C26“3 (C) and connect to C26“4 (C). *

SWITCH WIRING
()Fig. 2. Connect on 850mmf capacitor, C19, and a100K 5% resistor,
R34, from IB (S) to 1C (S).
()Fig. 2. Connect a500mmf capacitor, C20, and a100K 5% resistor, R35,
from 5C (S) to 5B (S).
()Fig. 2. Connect a5000 mmf 10%capacitor, Cl 8, and a 4. 7meg resistor,
R36, from 7C (C) to 8A (S).
()Fig. 2. Connect a2700mmfcapacitor, C21 ,anda 2.2 meg resistor, R38,
from 8D (S) to 9B (S).
4
()Fig. 2. Connect a3300 mmf capacitor, C17, and a560K resistor. R37,
from 1ID (S) to 11 A(S).
()Fig. 2. Connect ablue lead from 4D (S) to 7C (S).
()Fig. 2. Connect a2“ blue lead to 12C (S). Leave the other end free.
()Fig. 2. Connect one end of aJmfd 20% capacitor, C25, to 2D (C).
This lead should be only 1“ long. Leave the other end free.
()Fig. 2. Connect abare lead from 2D (S) to 3E (S).
()Fig. 2. Connect a2" blue lead from 10E (C) to 6E (S).
()Fig. 2. Connect a5" pieceof bare wire to 8F (C). Leave the other end
free.
()Fig. 2. Cut four 5" length of shielded cable. On one end ofeach, strip
back the braided shield and outer insulation 3/4“ .Strip back the inner insu-
lation 3/8". (Call this end "A".) On the other end of each (end nB"), the
outer insulation is stripped back 1", the braid shield 3/4", and theinnerin-
sulotion 3/8“
.
()Fig. 2. Connect the inner leads of theffour cables (end "B"), so that one
connects to each of the following four switch terminals:
()IF (S) ()2F (S) ( ) 11F (S) ()12F (S)
()Fig. 2. Cut a5“ piece of bare wire. Wrap this wire one turn around
the exposed outer braid on the "B" end of each of the shielded cables now
connected to 2F, IF, 12F, and 1 1 Fconsecutively and in that order, leaving
3/8" of bare wire between wrappings. Solder the bare to the outer braid on
each cable quickly with ahot, clean iron so as to minimize heating of the
cable insulation. Connect the free end of the bare wire (coming off the braid
of the cable connected to 1IF) using spaghetti, to 8F (S).
()Fig. 2. Cut a6" length of shielded cable. On one end, strip back the
braided shield and outer insulation 3/4" .Strip back the inner insulation 3/8"
.
(Call this end "A".) On the other end (end "B"), the outer insulation is
stripped back 1" the braided shield 3/4" and the inner insulation 3/8". On
end "B", wrap one turn of a2" piece of bare wire around the braided shield
and solder with aminimum of heat. Connect the inner leadtf end "A" to
10E (S). Leave end "B" and the small piece of bare wire free.
SI R35 C20
Fig.
»

FRONT AND REAR PANEL ASSEMBLY
()Fig. 3. Mount the 500K pot., R2, the loudness control pot., R14, the
1meg pot., R7, and the 0.5 meg center-tapped pot with switch, RIO. Use
two 3/8" hex nuts, one lockwasher and one flat washer on each control.
()Fig. 3. Mount the convenience outlets, J8 and J9, as shown. Use two
*6“32 screws, two *6 hex nuts, and two *6 lockwasher on each outlet.
()Fig. 3. Mount the sinale input Jack, J7, as shown. Use two *6-32 screws,
two ^6 hex^wts, and two '6 lockwashers.
()Fig. 3. Mount the terminal board, TB3, as shown. Use two ^6~32 screws,
two *6 hex nuts, and two ^6 lockwashers. Mount aone post right terminal
strip, TB2, under one lockwasher as shown.
()Fig. 3. Mount the dual input jack, J5“6, as shown. Use four *6“32
screws, four *6 hex nuts, and four *6 lockwashers. Use an insulating bakeIite
between the dual jack and the chassis. Mount aone post left terminal strip,
TB1 ,under one lockwasher as shown.
()Fig. 3. Mount two dual input jacks, Jl~2, and J3~4. Use four 32
screws, four ^6 hex nuts and four *6 lockwashers with each. Do not use any
insulating bake! ite or terminal strips (Fig. 4).
()Fig. 3. Mount the fuseholder, XF1, as shown.

R14
—
R2 —
-
R3 —
-
R1
R44"--.
R45
C23

REAR PANEL WIRING
()Fig. 4. Connect a33K 20% resistor, R40, from J5“2 (C) to TB1 (C).
()Fig. 4. Connect a2" black lead from J5”2 (S) to J6“2 (C).
()Fig. 4. Connect a47mmf capacitor, C22, from J5“1 (C) to TB1 (C).
()Fig. 4. Connect apiece of bare wire from J5”l (S) to TB1 (C).
()Fig. 4. Connect a68K 20% resistor, R39, from J6-1 (S) to TB1 (C).
( ) Fig. 4. Cot a7" piece of shielded cable. On both ends, the outer in*
sulation is stripped back T", the braided shield is stripped back 3/4" and the
inner Insulation is stripped back 3/8" .Wrap one turn of a3" piece of bare
wire around each end of the braided shield and solder. Connect the inner
lead of one end to TB1 (S), and the inner lead of the other end to XV1“7 (S).
Connect the bare wire at one end (covered with spaghetti) to J6“2 (S), and
the other bare wire to ground lug "A" (C).
()Fig. 4. Mount the switch, Si ,as shown. Use two 3/8" nuts, one 3/B"
lockwasher and one 3/8" flotwasher (Fig. 3).
>4 ()Fig. 4. Connect the bare wire from Sl“8F h> J3”2 (S).
()Fig. 4. Connect thefour ends "A” of the shielded cablesfromSI as fel-
lows:
IF to J3“1 (S) HFtoJl-l(S)
2F to J4-1 (S) 12F to J2-1 (S).
()Fig. 4. Connect the black lead from the output transformer, T2, to TB3“
()Fig. 4. Connect the slate lead from T2 to TB3-2 (S).
()Fig. 4. Connect the green lead from T2 to TB3-3 (S).
()Fig. 4. Connect the yellow lead from T2 to T83”4 (C).
()Fig. 4. Connectone end ofabare wire to TB3~1 (S). Pass the other end
thru XV5-1 (C) and Connect to ground lug “B" (S) on XV5.
()Fig. 4. Connect a10K resistor, R32 and alOOmmf capacitor. C16, from
TB3-4 (S) to TB2 (C).
( ) Fig. 4. Connect an 10" black lead fromTB2 (S) to XV8-3 (C). Run the
lead along the chassis as shown.
PRE-AMPLIFIER WIRING
()Fig. 4. Connect a1.138K resistor, R41, from XVI “8 (C) to ground lug
"A" (S).
()Fig. 4. Connect the blue lead from S1-12C to XVI “8 (S).
()Fig. 4. Run the free end of C25 under R4I and connect to XV1“1 (C).
The capacitor should be perpendicular to the chassis. Use spaghetti.
()Fig. 4. Connect a117.7K resistor, R44, from XV1-1 (S) to TB5”1 (S).
()Fig. 4. Connect a375K resistor, R45, from XV1“2 (C) to TB5“2 (C).
()Fig. 4. Connect a200K resistor, R42, from XV1-6 (C) to TB5“3 (S).
()Fig. 4. Connect a.02mfd GMV capacitor, C23, from XV1“6 (S) to
XV1“2 (S). Use spaghetti.
()Fig. 4. Connect a2.4K resistor, R46, anda lOmfd capacitor, C24, from
XVI-3 (S) toTB5”2 (C). Note that the negative lead goes to ground (TB5“2).
()Fig. 4. Connect ashort piece of bare wire covered with spaghetti from
the center shield post of XVI (S) to TB5-2 (S).
()Fig. 4. Connect a56K resistor, R1, from R2“l (S) to TB6“2 (C).
()Fig. 4. Connect the free end of the inner wire of the shielded cableon
S1-10E to TB6~2 (S). Cover the bare wire soldered to the braided shield with
spaghetti and connect to R2~3 (C). Run lead away from chassis.
TONE CONTROL CIRCUIT
()Fig. 4. Connect a330K resistor, R3, from TB6-1 (C) to R2-2 (C).
()Fig. 4. Connect a.25mfd capacitor. Cl, from TB6-1 (S) to XV2-1 (C).
Use spaghetti on both ends.
( ) Fig. 4. Connect a8" green lead from R2-2 (S) to XV2-2 (S). Run wire
In the bend of the chassis.
()Fig. 4. Connect a4" black lead from R2~3 (S) to R14-3 (C).
()Fig. 4. Connect a2200mmf capacitor, C4, from R7"l (C) to R7-2 (C).
()Fig. 4. Connect a68K 5% resistor, R6, from R7-1 (S) to R10-1 (C). Use
spaghetti on both ends*

C5
R7

Uut 5LCo,
nneC!°68K 5% re,iUor»R8»from R7-3 (C)to R10-3(C). li>e
spaghetti on both ends.
()Fig. 5. Connect a3300mmf capacitor, C5, from R7-2 (C) lo R7-3 (S).
,~d*- R,0‘3(c><«• •- -
LI F!?’ 5'Ccaate!°:!rfd
,20% capacitor, C7, from R10-3 (C) to XV2-6
SL
*
sm. a“*1
()Fig. 5. Connect a.05mfd capacitor, C3, from R10-1 (S) to XY2-1 1C)
JSKntruC7"-S
()Fig. 5. Connect a470K 5% resistor, R9, from XV2“7 (C) to R7-2 (S).
()Fig. 5. Connect aiOOmmf capacitor, C6, from R10-2 (S) to XV2~7 (S).
,
(
.D1(
F*9s 5*Connoct °Plec»of bare wire from R10-6 (S) to ground lug
Li W2-8 ** *'2.
()Fig. 5. Connect a100K 10% resistor, R1 1 , fromC27-3 (C)to XV2"6 (S).
UFl .
9;5-Co"necfa33
K
1/^W 10%resistor, R4, from C27-3 (C)loXV2-l
(S). Solder mounting lugs of C27 and C26 to chassis.
LL Sfc-i <s?T^V<c>* '
°
<*”**>*• C2.
()Fig. 5. Connect a3" black lead from R14-3 (S) to TB9~1 (C).
PHASE INVERTER WIRING
()Fig. 5. Connect a10K resistor, R15, from R14-2 (S) to XV3-2 (S).
()Fig. 5. Connect a470 Qresistor, R16, from XV3“3 (S) to TB9-1 (S).
Uto C27-9 ?r\ ne
r°n®°fihe *T* matched 22K r®»i*tors, R20, from TB9-2
£. w.mi m-m’oH,w “K°f*• —»*. ti».
()Fig. 5. Connect abare wire from XV3“6 (S) to TB9~2 (C).
()Fig. 5. Connect one end of a47K resistor, R17, to TB7-4 (C). Pass the
other end through XV3-7 (C) and connect to XV3-1 (S).
()Fig. 5. Connect a4.7K resistor, R18, from TB7-4 (C) to TB7-3 (C).
()Fig. 5. Connecta5000mmf20% capacitor,C9,from TB7“3 ($) toXV3“7($).
()Fig. 5; Connect a2" blue lead from C27“1 (C) to TB7~4 (S).
()Fig. 5. Connect o33IC1/2W resistor, R43,fromC27-4(S) to C27-3(C).
()Fig. 5. Connect a47K resistor, R13, from C27~l (C) to C27-3(S).
()Rg. 5. Connect a22Kresistor, R21, from C26"3 (C) to C27"2 (S).
()Fig. 5. Connect a33K 1W resistor, R22, from C26"3 (S) to C27-1 (S).
2(cf9’5’Conneet a-Imfd 10% capacitor, CIO, from TB9-2 (S) to XV4-
( ) Fig. 5. Connect a.1mfd 10%capacitor, Cl 1,from XV3“8 (S) to TB7“1 (C).
()Fig.5. Connect abare lead with spaghetti from TB7-1 (C)toXV4*7 (S).
DRIVER AMPLIFIER
()Fig. 5. Connect a470K resistor, R24, from TB7-1 (S) to TB7-2 (C).
()Rg. 5. Connect one end of a560Q resistor, R47, to TB7-2 (C) Pass
the other end thru XV4-8 (S) and connect to XV4-3 (S).
()Fig. 5. Connect a47K 2W resistor, R26, from XV4-1 (C) to TB4 (C)
Connect the other 47K 2W resistor, R25, from XV4-6 (C) to TB4 (S).
()Fig. 5. Connect a470K resistor, R23, from XV4-2 (S) to TB7"2 (S).
(C)
F'95C°nnect a*1mfd 10% capacitor, C13, fromXV4-l (S) to XV6“6
1I!'9'5‘Connect a.1mfd 10% capacitor, C12, from XV4~6 (S) to XV5“

R30
R27
TB8
R29^
R28
Cl 5
XV5
XV6

OUTPUT STAGE
( ) Fig. 6. Connect aIK resistor, R29, from XV5“6 (C) to XV5”5 (S).
()Fig. 6. Connect aIK resistor, R30, from XV6“6 (C) to XV6“5 (S).
()Fig. 6. Connect a100K, 5% resistor, R28, from XV5-6(S) to XV5-1 (S).
()Fig. 6. Connect a100K, 5% resistor, R27, from XV6~6 (S) through XV6"
1(S) to ground "G" (S) on XV6.
( ) Fig. 6. Connect the 330 mmf capacitor, C15, fromXV5-3 (S) to TB8 (S).
Be sure to use spaghetti on both pigtails.
()Fig. 6. Connect a4" yellow lead from XV5”8 (S) to XV6“8 (C).
()Fig. 6. Connect a2" yellow lead from XV6"8 (C) to R33~2 (C).
()Fig. 6. Connect a50mfd capacitor, C14, from R33“2 (S) to ground “J"
on XV7 (S). Note that the negative lead goes to ground "J" .Use spaghetti.
()Fig. 6. Connect a350 Q7W resistor, R48, from XV6“8 (S) to ground “K"
(S)onC26. Dress resistor against chassis. Use spaghetti .Dress adfacent leads
away from resistor to avoid damage by heat generated in operation.
FINAL WIRING
()Fig. 6. Connect a6K 10W resistor, R31 ,from C26-4 (S) to XV7-8 (C).
()Fig. 6. Connect a4" blue lead fromXV7-8(S)thru.C26-1 (S)toC26~2 (S).
()Fig. 6. Connect a.03mfd 20%capacitor, C28, from R10”4 (C) to ground
lug "C"
.
()Fig. 6. Connect one black lead from the power transformer T1 to RI0"4
(C). Connect the other black lead to the fuseholder XF1”1 (S).
()Fig. 6. Connect ablack lead from XF1 **2 (S) to convenience outlet J9~1(C).
()Fig. 6. Connect, a11/2" piece of bare wire from convenience outlet
J8“l (S) to convenience outlet J9-1 (C).
( ) Fig. 6. Connect a15" black lead from convenience outlet J8“2 (S) to
R10-4 (S).
( ) Fig. 6. Connect a14" blue lead from convenience outlet J9~2 (C) to
R10-5 (S).
()Fig. 6. Cut an 8" length of shielded cable. On one end (end "A"), ittip
the outer insulation back 1", the braided shield 3/4", and the inner insulation
3/B". On the otheir end (end "B"), strip the outer insulation and braid back
3/411 ,and the inner insulation 3/B". Wrap one turn of a2" length of bare
wire around the exposed shield at end "A" and solder. Connect the inner lead
of end "A" to J7“1 (S) and the bare wire to J7“2 (S). Connect the inner lead
of end "B" to R10-3 (S).
()Fig. 6. Insert a3/B" grommet into the hole at the rear of the chassis.
Pass the line cord through this grommet. Knot the line cord inside the chassis
3" from the end. Connect one lead to J9“l (S) and the other lead to J9“2 (S).
FINAL STEPS
You have now completed the assembly and wiring of your amplifier. When
you have completed the following steps your amplifier will be ready for use.
1)To catch any wtrlng errors, it is suggested that the entire wiring be checked
point-by-point against the wiring instructions (and preferably also against the
schematic wiring diagram In order to become more familiar with the component
layout and circuitry). While doing so, check for rosin joints, loose lumps of
solder, poor lead dress, and accidental shorts or leakage paths arising from the
flow of rosin between contacts (remove with astiff brush dipped in carbon
tetrachloride, being careful not to spring contacts when cleaning switches).
2) Clean socket XVI with carbon tetrachloride using astiff brush. It is also
advisable to remove the tube and shield from XVI ,and clean the socket and
pins on top of the chassis.
3) Insert VI through V7 in their correct sockets. Place shields over VI andV2.
4) If the amplifier ts not to be installed in aconsole, mount the control plate
by slipping it over the control shafts and using two *4-40 X1/8 B.H. screws
to fasten It to the front chassis apron (see Fig. 7). If the amplifier is to be
installed in aconsole, the mounting of the control plate is taken care of in
INSTALLATION in the Instruction section.
5) Mount the knobs on the front panel. All controls should be set at their
most counter-clockwise position. The knobs are pushed onto the shafts with
the dot pointing to the following markings.
CONTROL MARKING
SELECTOR TAPE
LEVEL 0
LOUDNESS 0
BASS -5
TREBLE OFF

Crl
Use the knobs with the short shanks If the amplifier is not to be installed In aeon-
sole. Theknobs with the longshanks are to be usedlf the amplifier is installed
in aconsole. In the latter case, the knobs areflnally placedonthe shafts only
after console Installation is completed. See INSTALLATION in the Instruction
section.
6)
IMPORTANT: BE SURE TOMAKETHE FOLLOWING RESISTANCECHECKS
BEFORE CONNECTING TO THE AC LINE: Checkforacold dc resistance of
3ohms across the AC plug with the AC power switch turned on; check for a
resistance of at least 70ohms between ground and pins 4and 6of XV7; check
for aresistance of at least 70K ohms between the positive terminal of each
section of the multi-section electrolytic capacitors, C26 and C27 to ground.
Allow sufficient time for the electrolytic capacitors to be .charged by the ohm-
meter battery when they are involved In the measurements. These measure-
ments constitute areasonable check of the power supply components and wir-
ing before applying power. If you fall to obtain these resistance values, do
not connect the instrument to the ac line until the cause is dlscoveredand the
condition remedied.
7) OPERATIONAL CHECKS ON COMPLETED KITS: In the Instruction part
of this manual, you will find asub-section In the Installation section titled
"Electrical Connections” •Read this carefully and connect your speaker,
phonograph, and tuner to the amplifier in accordance with the instructions
given. Then read the section titled tt OperatIng Instructions" and operate all
the controls, checking aurallyfor the results described. If the amplifier does
not operate at all or operates incorrectly, use the trouble shooting chart and
the Voltage and Resistance chart to discover and remedy the difficulty. As
the Trouble Shooting chart presumes aproperly wired amplifier, which may
not be the case, recheck the wiring for errors or reversed connections and
continuity.
8) Press aspeed nut in place over each hole on the bottom flange of the chassis
(see Fig. 8).
9) If the amplifier ts not to be Installed In aconsole. Insert the rubber feet
In the openings provided in the bottom plate. Whether the amplifier Is to be
Installed in aconsole or not, mount the bottom plate on the chassis, using
4*8~32X3/B" on the front and rear flanges and4 ^8*32X1" on the side flanges.
(It is essential that the bottom plate be mounted on the amplifier at the start
and during the process of console installation described In the Instruction sec-
tion, until that point In the installation procedure where It is Instructed to
remove the bottom plate temporarily for use as atemplate.)
10)
Installation, electrical connections, and operation will be found in the
Instruction section of this manual .Precede to the Instruction section at this
point. SERVICE
If you are still having difficulty, write to our service department listing all
possible Indications that might be helpful. If desired, you may return the in-
strument to our factory whereit will be placed in operating condition for $9.50
plus the cost of parts replaced due to their being damaged in the course of
construction. This service policy applies only to completed Instruments con-
structed in accordance with the Instructions as stated In the manual. Instru-
ments that are not completed or Instruments that are modified will not be ac-
cepted for repair. Instruments thatshow evidence of acid core solder or paste
fluxes will be returned not repaired. NOTE: Before returning this unit, be
sure all parts are securely mounted. Attach atag to the Instrument, giving
your home address and the trouble with the unit. Pack very carefully in a
rugged container, using sufficient packing material (cotton, shredded news-
paper, or excelsior), to make the unit completely Immovable within the con-
tainer. The original shipping carton Is satisfactory, providing the original
Inserts are used or sufficient packing material ts inserted to keep the Instru-
ment immovable. Ship by prepaid Railway Express, if possible, to the Elec-
tronic Instrument Co. ,Inc., 33"*00 Northern Blvd., L.I.C. 1, New York. Re-
turn shipmentwill be made by express collect. Note that the carrier cannot be
held liable fordamages in transit if packing, IN HIS OPINION, is insufficient.

SYMPTOM
Excessive phono hum
Excessive phono noise
Sustained oscillations
CAUSE
12AX7 (VI) defective
FIL leads dressed too close to grid lead,
C27 defective
Tube shield not making electrical contact to
base or base not making electrical contact to
chassis.
Outer braid connection on phono 1or phono 2
Input facks accidentally shorting to chassis at
the |ack.
Outer braid of shielded lead going from phono 1
and 2Jacks to switch not grounded at switch as
required.
Shielded lead contacting chassis ground at other)
than required point.
VI socket and contacts dirty.
Poor dress of output transformer T2 leads.
Sustained phono microphonics I12AX7 (VI) defective
Hum on all Inputi 12AX7 (V2) defective, not properly shielded,
or dirty socket and contacts.
Dress of power transformer T1 leads.
REMEDY
Replace
Dress fll. leads away from grid lead.)
replace C27.
Check and correct
clear short at Input Jack
repair
repair
clean thoroughly with carbon tetra-
chloride.
Dress all InpotJeads and 12 leads a-
way from each other. Keep T2 leads
away from Input lacks.
replace 12AX7 (VI) with selected
new 12AX7 or with premium 12AD7.
see below
correct
!f *troubl »I, no output "J™ check ac signal voltages starting at the Input and working step-by-step toward
lh?rSf/PU 'i
LEVEL *LOUDNESS controls to maxtmum(10)and BASS and TREBLE controls to their mid-points (0). Use
al!9™1'"f alw,PPl,ed hy E.CO 377 Sine &Square wave Audio Generator, ^addition, use
out of 0 4 viS whtaK PTr.L
0b ,,*ialeV“‘ °- 004volt Mto PHONO Input 1from an audio generator out-
frHe°nerator1 'Lhl Jh!"hT“ J"ea,ur^lowe*' AC volts range of your VTVM (also Improves signal to hum
221 or 214^ S* nPUf
.?’P®^,nce "VM for 0,1 AC *,9nal voltage measurements (such as the EICO 232 ,249,
221 ,or 214). This procedure should suffice to localize the defective stage.
°n“T'Z'j fSt?rted OUtput'to* *b®replacement, signal tracing, or procede directly to voltage and
any circuit cTangeT*"
1*’ ?de‘fred/ prem,um 5881 »«b«maybe u*ed as direct replacements for the 6L6 GB tubes without
When the defective stage 1, localized, procede to aresistance and voltage check of the stage, using the data In the re-
?«^n
e
cret)SaSorto?'te
^Disconnect the amplifier from the power line and discharge capacitors prior to making any
o, bo* of 6L6 GB ootpo, K,b« V3 and V4. Do nor him the o»p.mo, J,
TROUBLE -SHOOTING TYPICAL TUBE STAGE
1•Check tube
2. Check plate and cathode resistors.
3. Check coupling capacitors for leakage or short.
c0U*PU*|tQ9G*check dc resistance of transformer windings.
5. Check grid leak resistor for open.
6. Check cathode by—pass capacitors for short.