Eico HF-32 User manual

30 WATT HIGH FIDELITY INTEGRATED AMPLIFIER
%
MODEL
HF-32

I
MODEL HF-32
30 WATT HIGH FIDELITY
INTEGRATEDAMPLIFIER
general description
GENERAL
The HF“32 is an excellent example of EICO's "low-sil-
houette" design methods, whereby compactness and richly
attractive appearance are obtained without compromising
good engineering practice. Power tubes are well separated
from each other and heat-sensitive components, undesir-
able coupling are avoided, and asingle horizontal chassis
is used which greatly simplifies kit construction and main-
tenance. It is unquestionably atop value in the amplifier
field.
FEATURES
1. Three low level inputs for magnetic phono, tape head,
and microphone.
2. Four phono equalizations (including RIAA) and NARTB
Tape Head equalization. Equalization circuit is of the
extremely low distortion feedback type.
3. Three high level inputs for tv, tuner, crystal/ceramic
cartridge, or tape.
4. Single switch selects any input and/or equalization.
Unused inputs are shorted at every position of the input
selector for zero cross-talk.
5. DC heater power supplied to preamplifier tube to in-
sure lowest hum. DC superimposed on all other tube fila-
ments.
6. Extremely low distortion bass and treble tone controls
of the variable crossover, feedback type. Printed circuit
couplate simplifies wiring.
7. Rumble and scratch filter circuits inserted by front panel
slide switches.
8. ACehtralab printed-circuit, prewired loudness control
(compentrol) plus aseparate level control, both on the
front panel. By pre-setting the panel level control as in-
structed, the loudness control will automatically provide
correct Fletcher-Munson compensation at the setting whir h
gives the desired listening level.
9. Low impedance output to tape recorder, useful on all
inputs. Affected by filter circuits and tone controls.
10. Four EL84 push-pull parallel output stage with very
high quality 6lb. output transformer having extensively in-
terleaved windings and grain-oriented steel laminations,
11. Williamson-type power amplifier circuit consisting of
avoltage amplifier direct coupled to asplit-load phase
inverter driving the output stage. The high power sensi-
tivity of the output stage eliminates the necessity for ad-
ditional driver stages, permitting the use of alarge amount
of inverse feedback with ahigh stability margin. •
12. Two EZ81 rectifier tubes having warm-up character-
istics matched to the output tubes comprise aconservatively
rated rectifier section of exceptional reliability. Filter
electrolytics also operate well below maximum ratings and
voltage surges at starting are eliminated.
13. Switched and unswitched convenience outlets.
14. Fuse and panel mounted fuse holder, pilot lamp.
15. Hum balance control.
16. Newly designed "low-silhouette" construction, utiliz-
ing horizontal chassis to permit proper layout and compo-
nent separation necessary for long component life. Ex-
tremely flexible design permits easy console installation
with complete shielding and adaptability to any panel-thick-
ness.
1

SPECIFICATIONS
Output Power;30 watts continuous, 47 watts peak.
*.KA nu^ortion (60 rn.&7kcat4:Ti: 2% at 30 watts;
1% at 20 watts, 0.5% at 10 watts.
*Total Harmonic Dtstortlo_n ibelow l%20cps—20kc within
1db of 30 watts.
«Frequency Response;1w:±0.5db 10cp$-50kc,
^lOcps-lOOkc; 30 w: ±0. 5db 15cp$ -50kc, ±1.5db
IScps-lOOkc. ±0.1 db 15cps-30kc at ony level
from 1mw to 30 w; no peaking or raggedness out-
side audio range.
Response;20cps to 20 kc essentially undls-
torted.
I
Inverse Feedback: 20 db
<t.n.itivitv(lprut for rated output): Mag. Phono -5milli-
-® vllts; Tape Head -2millivolts. Microphone -4
mllllUlts: High level (TV, TUNER, AUX. )- 0.4
M..„. ANoise Le--I (helow rated output Mog. Phono-
;**60db down! TapeHead-** 51 db down. Micro
phone_57 db down. TV, TUNer, AUXlllary_75 db
down. (Maximum gain, tone controls set at flat
•.•_ \
nn^ Rumble Filters: Scratch filter Introduces ap-
proximately 12db/octave slope obo''® Skcj Rum-
ble filter Introduces opproxlmately 12db/octaye
slope below 70 cps.The nominal cut-off frequencies
are points at which response is 6db down when the
corresponding filter is Introduced.
rR.nuirements: 117V,60cps; UOwatts consumption.
Tubes: 2- ECC83/12AX7, 2" EC90/6C4,4- EL84, 2- EZ81.
<;tnbilitv Margin:15 db
Dompina Factor;above 10, 20cps to 20 kc.
<; panl.pr Connections; 4, 8, and 16 ohms.
rpntrol Range: at lOkc -13db boost, 15db cut, at
SOcps -14db boost, 15db cut.
Equalization: Mag Phono Input: RIAA, COLumbia (orig-
1P^ lONdon. American 78. Tape Head In-
put: NARTB.
Size: 15" wide, 43/4" high, 10 1/2" deep.
Weight:
*Measured from high level Inputs with tone controls set at
“flot“ positions and loudness control at maximum (no ef
feet).
** Includes effect of equalization.

\i
omrxtmmAL
a) HEAT DISSIPATION (VENTILATION/;: In common wfrh
•V^iVcfinvlc. ,^V\« HF“32 produces consider
^Ote oV Vvow# \%ckAo%T\ed otOMtA 'fneVeoft pro^McNr^^ de-
ments, these elements will over-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 suitability of alocation.
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 air is set In
motion which continually removes heat from the ampli-
fier. (In particular, we are mainly concerned with the
major heat-producing elements; the four EL84 output tubes
and the two EZ81 rectifier tubes.) If there is any impedi-
ment to or constriction of the air flow, the essential process
of heat removal will be adversely affected.
Adequate ventilation will be provided if the amplifier is
installed In an open-back console provided that the top
of the amplifier Is spaced at least two Inches below any
shelf mounted above It. If the cabinet is 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 air to en-
ter at the bottom and hot air to leave at the top.
If the amplifier is not installed in aconsole, it may be
situated on an open surface or on ashelf of abookcase.
Four rubber feet are aIso provided so that the amplifier will
not mar the surface of furniture on whici: it is placed.
b) EASY ACCESS TO CONTROLS: Mount the amplifier
at aheight which will permit easy manipulation of the con-
trols. Tuner controls should be located nearby.
c) ACCESSABILITY TO PARTS: Tubes are the most fre-
quently replaced Items In electronic equipment. If the
amplifier is installed in aconsole, 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 comparison, and connection or dis-
connection of aportable tape recorder which is stored o-
way when not In use. If antennas are strung around the
back of the console In 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 recommended), pro-
vide sufficient separation to minimize mechanical speaker
vibration reaching the amplifier. The minimum separation
is about one foot.
CONSOLE A^OLINTIIMO
o; C>pmrattonm on cctnmetim ftortt ponol pr»ltmtnary to omplt-
fler mounting: (1) Tape the panel template provided to
Wt\% a(T\ \\ ^
amplifier mounting shelf. Note: When shelf is not avail-
able, tape the template at any convenient spot on the face
of the console. (2) Use an owl or anail to pierce the
centers of the four extreme outer holes for mounting the
control plate, to transfer their locations to the console
panel beneath. (3) Trace out the rectangular cutout with
on awl or nail and then pierce the centers of the four 1/2"
holes, one in each comer of the cutout. (4) Remove the
panel template. (5) Drill the four 1/2" holes in the con-
sole panel, one in each comer of the rectangular cutout
area. Cut out the rectangular piece with akeyhole saw,
using the four 1/2" holes as starting holes.
b) Amplifier mounting In console: (1) Pull off the control
knobs. (2) Remove the four screws that fasten the bezel
to the side pieces and remove the bezel. (3) Remove the
two screws and nuts that fasten the control plate to the
bezel. The bezel is not used in console mounting. (4)
Fasten the control plate to the console panel with the two
^4 X3/8 wood screws supplied. (5) If the rubber feet have
been Inserted In the bottom plate, remove them. (They may
be pried out with athin screwdriver.) (6) Place the unit
on the mounting shelf and slide it forward until the slide
switch support brackets are up against the panel and both
slide switches accessible from the front; the control shafts
should be approximately centered In the corresponding
holes in the control plate. (7) With asharp pencil, draw
the outline of the side and rear 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 lines 3/16" in-
side the original side edge lines. (8) Now remove the
knobs and take the chassis off the shelf. (9) Remove the
6screws which fasten the bottom plate to the chassis. (10)
Place the bottom plate exactly In the outline drown on the
shelf and mark the position of the center hole on the left
side and the center hole on the right side. (11) Remove
the bottom plate and drill each of the marked holes on the
shelf to adiameter of 1/4". (12) Refasten the bottom
plate to the chassis, with thefourof the six ^8 x3/8 screws
previously removed, using the two holes at the rear and the
two holes at the front of the chassis. (13) 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. (14) From the bottom side of the shelf,
insert a#8x 1" screw, with a1/2" flat washer against
the head, through both the left and right side center holes.
These screw engage the stamped nut over each hole on
the chassis flange and when tightened secure the chassis
to the shelf.
3

electrical installation
GENERAL
a) SPEAKER CONNECTIONS: To eonnoct your speaker
to rhe amplifier properly, you must know Ih rotod imped-
ance. This may be read off tbe speaker nameplate. Con-
nect one speaker lead to the "G“ terminal on the rear apron
and the other speaker lead to the nearby terminal corre-
sponding to the rated speaker Impedance (4,8, or 16 ohms).
Plastic-covered lamp card may be used far distances up to
50ft. with little power loss. For shorter distances, TV
antenna lead can be used, portlculorly If It Is desired to
run the sepaker lead under arug.
If It is desired to use two similar or Identical full-range
speaken of the some rated impedanr e(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. (Itmaybe 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) LO &HI MAG. PHONO INPUTS: These are intended
for use with phonographs having magnetic cartridges, or
with ceramic or crystal cartridges having adaptors for mag-
netic cartridge input (to permit choice of equalizations).
The HI Input provides a 3 :lattenuatlon of the input signal
for very high output cartridges that might cause overload-
ing af the preamplifier stage. Most magnetic cartridges
(low to average output) should be plugged into the bO in-
put (direct), which provides the highest gain and the bwt
signal-to-noise ratio. Use the Hi input for exceptionally
high output cartridges or if you can detect distortion on
peaks when the cartridge is connected to the LO input,
which is eliminated when the cartridge is connected to the
HI input. The loading resistance presented to the cartridge
at both LO and HI inputs is 100,000 ohms (lOOKO). If a
lower loading resistance is required by the particular car-
tridge used, connect aresistor of appropriate value across
the input. The resistor should be placed across the leads
coming from the cartridge at some suitable point in the
phonograph (see Fig. 1). The value of this shunt resistor
fR,)can be determined from the desired loading resistance
Rl) by this formula R, »100/000 ohms, or this
table: for Rl »50KC1, use R, =for Rj -33K, use
R, »50KO ifor Rl *25KQ ,u*® R, =33Kn
.
c) TAPE HEAD INPUT; Tbh Input It Intended for receiving
the output slgnol directly from the playback heed of »»o^
deck. NARTB tope head equalliotlon for 71/2 and 15 l|^
tape speed. I. opplled to signal. MIn ot t^lnpuj. T^
loading resistance' presented to the tape head Is 100,000
d) MICROPHONE INPUT: This input is intended for re-
ceiving the output signal directly from a
is preferable that the microphone used be of the high im
pedance type.
e) HIGH LEVEL INPUTS: Four high level Input (acks d«-
Ignated as Tuner, TV, Tape, and Auxiliary are provided for
connection of tuners, tv receivers, tape recorder playbMk,
and ordinary or RIAA equalizing crystal "
cartridges without adaptor. Ashleldedcablewithashleld-
ed "phono-type" plug should be used to connect each ot
these sources to the corresponding amplifier InputJack.
Unless the source has alow-impedance output such a. a
cathode follower (with which up to 50ft. of coble can be
used), use theshortestposslbleconnectionandlowcopoclty
shielded cable (cable having os low as 25 mmfd capacitance
per foot is available).
If the toner employed has avolume control to adjust ihe
output, set this control os follows. Turn the ompllfi«
LEVEL control to minimum and the LOUDNESS control
maximum. Play any recording on your phonograph ond turn
UP the level control to obtain an ordinary listening level.
VVithout touching the LEVEL or LOUDNESS controls, turn
the SELECTOR to TUNER and adjust the volume control
on the tuner to obtain approximately the same loudneu
level as was obtained from the recording. Inthe case where
h.ner has no output level control and olso In the case
Fig. 1

of the other high level Inputs, the independent LEVEL con“
trol on the front panel of the amplifier permits adjustment
of the level when changing inputs,
f) TAPE OUTPUT: Ashielded cable (up to 50ft. may be
used) with ashielded "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 tope recorder through this jack. All inputs are
affected by the level, control, the tone controls, and the
filters, but not the loudness control.
g) POWER CONNECTIONS: The power cord of the turn-
table and tuner may be inserted in the convenience out-
lets provided on the rear chassis apron. The receptacle
marked 117 VAC is intended for use primarily with aphono-
graph and provides 117 VAC regardless of whether the power
switch of the amplifier Is turned on or off in order to pro-
tect the phonograph mechanism. The receptacle marked
117VAC 15bW, SWITCHED, is "live" or"dead" depending
on whether the amplifier power switch is turned on or off
and is intended primarily for use with tuners. Equipment
drawing in excess of 150 watts should not be plugged into
this outlet.
HUM ADJUSTMENT
After checking the amplifier for proper operation, re-
move all input cables to the amplifier and make the follow-
ing control settings which hold throughout the process of
hum adjustment: SELECTOR at RIAA, LEVEL &LOUDNESS
to 10, TREBLE control at “S, BASS control at 0. Next
procede as follows: 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 and re-
insert it with the prongs reversed and listen again. Choose
the prong position which gives the least hum. Now con-
nect the tuner input connector to the amplifier input jack,
and with tuner set between stations and the tuner volume
control setata minimum, do the same with the power plug of
the tuner, using the 117VAC SWITCHED receptacle" on
the amplifier if desired. Finally connect the phono input
connector to the amplifier PHONO LO or PHONO HI in-
put as is required (turntable off and pickup arm at rest po-
sition) and do the same with the power plug of the turntable,
using the 117VAC convenience outlet* on the amplifier If
desired. When all of this is completed, adjust the hum
balance control on top of the amplifier chassis for least hum.
operation
PRELIMINARY: Be sure all tubes are firmly seated in their
sockets and that the tube shields are 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 control
clockwise from OFF and set It at zero Initially.
LISTENING TO PHONOGRAPH: Set the SELECTOR to
one of the record equalization positions on the dial. Do-
ing so automatically selects the phonograph input plugged
into the PHONO LO or PHONO HI input. For help in
choosing the recording curve appropriate to any parti-
cular record, refer to the section titled "RECORD EQUALI”
ZATION SELECTION". When in doubt as to which equali-
zation is most appropriate, use RIAA, which is the best
compromise for all records. Keep in mind that while the
positions offered cover most recording curves likely to be
encountered, additional separate and variable bass and
treble response adjustments are necessary for fully 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 any of the equalizations pro-
vided, and above all, the particular tastes of the listener.
LISTENING TO TAPE DECK (direct connection to tape
head): Set the SELECTOR to TAPE HEAD, which automat-
ically selects the TAPE HEAD input and NARTB tape head
equalization for the 71/2 and 15ips speeds. This equali-
zation is the industry standard for pre-recorded stereo and
monaural tapes.
LEVEL &LOUDNESS CONTROLS: Simply stated, the
purpose of the LOUDNESS control Is to provide compen-
sation for the increasing inefficiency of the human ear in
hearing bass and treble with decreasing volume level. The
LOUDNESS control, as It is turned counter-clockwise from
maximum clockwise rotation, not only decreases the volume
but increasingly emphasizes the bass and treble according
to the Fletcher-Munson curves (curves developed from a
statistical study of this 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 pro-
gram material to loud program material or the reverse with-
out occasioning achange in the loudness compensation.
To "set" the LOUDNESS control at any time, perform these
operations in the order given to avoid blasting or possible
damage to speakers of low power-handling 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 setting until arela-
tively loud listening level is obtained, d) Turn down the
LOUDNESS control until your normal listening level is ob-
tained with the LEVEL control set as just described. Proper
loudness compensation should now be obtained at any list-
ening level adjusted to with the LOUDNESS control. The
same reference LEVEL control setting will be suitable for
both phonograph and tuner listening 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
5

ad|usts, such as tv or acrystal cartridga connected to the
AUX, Input, It may be desirable to set the LEVEL control
to zero beforehand and then bring up the LEVEL control to
obtain the desired listening level to avoid blasting. %
BASS CONTROL: The plus sign on the right side of the
dial indicates that clockwise rotation from the mid-point
(0) Increases (boosts) base response; the minus sign on the
left side Indicate that counter-clockwise rotation from the
mid-point decreases (cuts) bass 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 bass response Is neither cut nor
boosted at this setting.
TREBLE CONTROL: The plus sign on the right side of the
dial indicates that clockwise rotation from the mid-point
(0) Increoses (boosts) treble response; the minus sign on
the leftside Indicates that counter-clockwise rotation from
tlie mId-poInt decreases (cuts) treble response. There is
r.o interaction with the BASS control. Start all adjustments
with this control set at the mid-point (0), which Is called
the “flat” position since treble response Is neither cut nor
boosted at this position.
RUMBLE FILTER: Rumble (low vibration) occurs at about
29cps in 4-pole record changers and turntables. Recorded
rumble will also sometimes be found in discs recorded before
the development of the Improved techniques in use today
(transmitted program material may also include records of
the latter type). Reduced rumble Is one of the objectives
in the design of turntables and changers for high fidelity
use, but the extent to which It is eliminated depends on the
quality and condition of the turntable or record changer
used. That Is why the rumble filter is provided. Note that
whether therumblefrequency itself is audible or inaudible
(depending on the extreme low frequency response of the
speaker system), it may still overload the amplifier or
speaker and cause distortion in the audible region. Insert
the rumble filter whenever recording to tape from records
played on adoubtful changer or player, in order to elimi-
nate any trace of sub-sonic rumble from appearing at the
recording head and eventually magnetizing it with in-
creased distortion level as aresult. The rumble filter also
eliminates tape overload from low frequency noise com-
ponents and thus provides cleaner tapes.
SCRATCH FILTER: The scratch filter is used for reduction
of noise with worn or scratchy records, particularly older
78RPM records, and for elimination of noise above 5KC
on AM broadcasts. It is particularly valuable in these
cases when recording on tape.
FILTER CIRCUITS VS. TONE CONTROLS: Note that the
filter circuits provide relatively sharp cut-offs, whereas
the tone controls provide gradual, frequency-proportional
changes in the response. One type of control is not a
substitute for the other and both may be used together to
achieve any desired response. It Is worth noting, however,
that the "variable turnover" tone controls employed In
this instrument maybe used to further sharpen the cut-off
when desired or effectively shift the cut-off frequencies
In either direction.
LISTENING TO TUNERS, TV, OR OTHER HIGH LEVEL
INPUTS: With the SELECTOR switch set at TUNER, TV,
or AUXILIARY, the corresponding high level Input from a
radio tuner, tv, tape recorder with built in preamplifier
-
equalizer, second tuner, or crystal cartridge will feed
through the preamplifier. Adjustment of the volume con-
trol on each source is discussed In the "Electrical Con-
nections" section under "High Level Inputs" and again
under "Level &Loudness Control" In this section.
MAKING RECORDINGS: Tape, wire, or disc recordings
may be made by connecting the recorder to the TAPE OUT”
PUT jack. See "TAPE OUTPUT" under "ELECTRICAL IN-
STALLATION" and the "RUMBLE FILTER" and "SCRATCH
FILTER" operating instructions.
RECORD EQUALIZATION SELECTION
Records are 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 bfore Spring 1954, records of which
the masters were made before this date may require any
one of several different equalizations (amounts of bass
boost and treble cut) by the amplifier to restore the origi-
nal bolance.
In the Spring 1954, the RIAA recording curve was adopted
by almost all record companies. At this time, all record-
ing companies use the RIAA recording curve. If an older
LP record does not seem properly equalized at the RIAA
position, try LONdon if it Is aLONDON (ffrr)or L*Oiseau-
Lyre record and COLumbia If it is ofalmostany other brand.
For most 78 rpm recordings, either the AMeri can 78 or the
EURopean 78 equalization will be found suitable.
maintenance
TROUBLE SHOOTING AND OPERATING NOTES
Your amplifier should require little service except for nor-
mal tube replacement. We recommend no substitutions for
the tube types used in this amplifier except as stated. All
the tube types used are distributed nationally, but replace-
ments can be obtained directly from EICO If desired.
To facilitate servicing, remedial and trouble-shooting pro-
cedures have been provided in the TROUBLE“SHOOTING
CHART that follows. AVOLTAGE AND RESISTANCE
CHART is also provided as an aid Ih locating defective
components. DC operating voltages are given both at no
signal and signal developing 30 watts output, as well as
the corresponding 1kc signal voltages.

TROUBLE-SHOOTING PROCEDURES
Connect aphonograph and speaker to the amplifier as de-
scribed in "Electrical Connections" and set controls for
phono listening. Play aknown high quality LP recording
on the phonograph. If there is no output to the speaker
or if the output is low or audibly distorted, 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 jack 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 maybe ametal pick—up arm
not grounded to the cable shield (try agood single ground
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 (try using
arubber mat on the turntable to Increase the separation of
the pick-up from the motor), or pick-up from apower trans-
former 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 ampli-
fier chassis atone pointonly, through the skirt of the input
connector where it plugs into the amplifier. Finally, try
agood building ground such as aconnection from acold
water pipe 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 maybe checked in asimilar
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 amplifier. Note
that on all inputs, the braid of the input cable should con-
nect to the amplifier only through the skirt of the input
connector. The cause and remedies for the following symp-
toms 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.
If the trouble is no output or low output, check AC signal
voltages and DC operating voltages starting at the Input
and working step-by-step toward the output. Set the
VOLUME iLOUDNESS controls to maximum (10), the
BASS and TREBLE controls to their mid-points (0),and the
SCRATCH &RUMBLE filters to OFF. Use a1000 cycle
sinewave signal, such as supplied by theEiCO 377 Sine &
Square Wave Audio Generator, In addition, use apre-
cision 100:1 attenuator to permit obtaining alevel of
0.005 volt fed into MAG. PHONO from an audio gen-
erator output of 0.5 volt, which can easily be measured
on the lowest AC volts range of your VTVM (also improves
signal to hum from generator). Use ahigh Input impedance
VTVMforall AC signal voltage measurements and aVTVM
or 20, 000 0/volt VOM for DC voltage measurements.
If the trouble is an excessively distorted output, try tube
replacement, signal tracing, or procede directly to voltage
and resistance measurements.
When the defective stage is localized, procede to aresist-
ance and voltage check of the stage, using the data In the
VOLTAGE and RESISTANCE chart. Disconnect the ampli-
fier from the power line and discharge capacitors prior to
making any resistance check and prior to removing any or
all of the EL84 output tubes. Do not turn the amplifier or\
with any of the output tubes removed .
CHECKING ATYPICAL TUBE STAGE
1. Check tube.
2. Check plate and cathode resistor.
3. Check couf^lng capacitors for leakage or short.
4. For output stage, check dc resistance of transformer
windings.
5. Check grid leak resistor for open.
6. Check cathode by-pass capacitors for short.
7. If no or low B+ voltage on tube, check decoupling
path for open or defective R40, R41, R42 and filter capac-
itor C31 or C32.
8. If wiring and circuit components including the tube
check O.K. and B+ voltage is excessive, check the de-
coupling path for short or defective R40, R41, R42.
Suspected trouble in the equalization, tone, filter, and
volume or loudness controls and networks should lead to
specific resistance and capacitance checks to localize the
trouble. In general, if the user suspects poor frequency
response, defective equalization, or defective operation
of the tone controls or filter circuits, the amplifier should
be tested thoroughly with audio generator, vtvm, and scope.
SERVICE
If trouble developes in your instrument which you can not
remedy yourself, write to our service department listing
all possible indications that might be helpful. If desired
you may return the instrument to our factory where it 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. 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 arugged container, us-
ing sufficient packing material (cotton, shredded news-
paper, or excelsior), to make the unit completely immov-
able within the container. The original shipping carton
is satisfactory, providing the original inserts are used or
sufficient packing material inserted to keep the instru-
ment immovable. Ship by prepaid Railway Express, if
possible, to Electronic Instrument Co. ,Inc. ,33 “00 North-
ern Blvd., Long Island City 1, New York. Return ship-
ment will be made by express collect. Note that acarrier
cannot be held liable for damages in transit if packing
IN HIS OPINION, is insufficient.

TROUBLE-SHOOTING CHART
SYMPTOM
Amplifier causes power line fuse
to blow. .Power line fuse blows a-
gain with V9 &VIO out of their
sockets.
Amplifier causes power line fuse to
blow. Power line fuse does not blow
again with V9& VIO out of their
sockets.
Any or all tube filaments not lit.
(except VI
)
VI filament not lit.
I
Output tube bias too high (re-
sulting In distorted output wave-
form).
DC voltage at V9,VI0 cathodes
(pin 3) Is Incorrect as specified
below.
a) No voltage.
b) High voltage.
c) Low voltage.
Excessive hum on mag. phono
or tape head.
Excessive noise on mag. phono
and tape head.
Sustained oscillations.
Sustained mIcrophonIcs on mag.
phono and tape head.
Hum on all Inputs.
CAUSE
Line cord, J9, JIO, primary or high voltage
secondary windings of T2 shorted Internally
or externally (wiring).
V9, VIO, C31, V5, V6, V7, V8, or T1 pri-
mary shorted Internally or externally.
Open tube filament.
Open lead from 6.3 Vwinding of T2. •
6.3 Vwinding of T2 open.
Open VI filament.
No connection or poor connection to pin 5
(fll. )of VI from common cathode con-
nection of V5, V6, V7, and V8.
Pin 4(fll.) of VI not grounded.
Same as above If VI filament not lit.
Open R26 If VI filament Is lit.
Defective V9 or VIO
C31 shorted Internally or externally.
Connection from C31 to pin 3of V9 &VIO
broken.
Connection to center tap of h.v. secondary
winding of T2 open.
Output tubes V5,V6,V7,V8 over-biased
or not drawing current. May result from
open R26,open filament or defective con-
nection to VI filament.
Excessive current drain In amplifier.
Defective V9, VIO.
VI defective
Fll. leads dressed too close to grid lead.
Tube shield not making electrical contact
to base or base not making electrical con-
tact to chassis.
Shielding and grounding of wiring to Input
jacks not exactly as Instructed and shown
In drawings.
VI socket and cantacts dirty.
Poor dress of output transformer T1 leads
VI defective.
V2 defective, not properly shielded, or
dirty sockets and contacts.
Dress of power transformer T2 leads.
REMEDY
Replace or repair.
Replace or repair.
Replace or repair.
Replace or repair.
Replace or repair.
Replace
Replace or repair.
Repair
Repair
Replace, repair, or see trouble-
shooting typical tube stage.
See trouble-shooting typical tube
stage.
Replace
Replace
Dress fil. leads away from grid lead.
Check and correct.
Correct
Clean throughly with carbon
tetrachloride.
Dress all Input leads and T1 leads
away from each other. Keep T1
leads away from Input jacks.
Replace
Replace, correct, or clean.
Correct
8

VOLTAGE AND RESISTANCE CHART
TUBE
ECC83/12AX7
VI
EC90/6C4
V2
K:C83/12AX7
V3
K90/6C4
V4
EL84
V5,V6
(r«ar)
EL84
V7,V8
(front)
EZ81
V9,V10
PIN^ OPERATING VOLTS OPERATING VOLTS SIGNAL VOLTS OHMS
AT NO SIGNAL
(DC UNLESS NOTED) AT30W OUT
(DC UNLESS NOTED) (1 KC) AT 30W OUT (UNIT DISCONNEC
ED FROM POWER)
162 56 .012 320KQ
200.0036 IIOKO
30.6 0.65 .0034 1.2KQ
400•
512.5 14.6 -17Q
698 92 .38 320KO
700.012 IMO
81.35 1.35 04.7KQ
96.3 7.3 §80
1141 142 1.16 125KO
2-e-•
3&4 filament (OVDC; 6. 3VAC between pins 3&4) 0-500
5141 142 1.16 125KO
600.38 500KO
77.5 7.4 .236 5.6KO
195 96 8.4 340KO
2001.16 180KO
3.95 .95 1.05 1.65KO
4&5 filament (OVDC; 6. 3VAC to pin 9) 0-500
6175 175 1.2 180KO
700.60 450KO
82206.8KO
9filament *
1195 185 7.4 92KO
2100 102 7.4 82KO
3&4 filament (OVDC; 6. 3VAC between pins 3&4) 0-500
5196 190 7.7 92KO
695 96 8.4 340KO
7100 102 7.4 82KO
100•7.4 330KO
2007.4 330KO
312.5 14.6 03300
4&5 filament (OVDC; 6. 3VAC between pins 3&4) 0-500
6007.4 330KO
7340 337 200 620 (T1 brown lec
8
9345 342 10 0
1007.4 330KO
2007.4 330KO
312.5 14.6 03300
4&5 filament (OVDC; 6. 3VAC between pins 3&4) 0-500
6007.4 330KO
7340 333 200 660 (T1 blue leocj
8
9345 342 10 0
1290VAC(60cps) 290VAC (60cps) -45-55 0
2---“
3345 342 200KO
4&5 filament (345 VDC; 6. 3VAC between pins 4&5) 200KO
6---•
7290VAC (60cps) 290VAC (60cps) -45-55 0
8---•
9----
All rotlitance moosuremonh, excopt those mode from pin 3of V9and V10(£Z81 rectifier)/ ore
mode with pin 3of V9 and VI 0grounded. All voltage and resistance measurements are meas-
ured to chouls with the controls set os follows: SELECTOR to RIAA, LEVEL &LOUDNESS
both at 10, SCRATCH &RUMBLE FILTER both at OFF, BASS &TREBLE controls both at 0. For
voltage measurements at SOW output, set the Input selector to the RIAA position and feed a
0.005volt(5mv)l kc signal to the LO MAG. phono Input |ack| connect aresistive (preferobly
non-inductive) load of equal resistance to the tap selected (±20%) and capoble of handling
60 watts. Voltage measurements are mode with aVTVM. Operating line voltage at which
voltoge measurements ore made Is IIZVAC, 60cps. NOTE: ALL VOLTAGE &RESISTANCE
VALUES MAY VARY NORMALLY BY ±15%.
O

SECTION AUX TV' TUNER MIC TAPE HEAD 78 RIAA .COL LON
SELECTOR A9-11 3-11 3-11 NC NC NC NC NC 5-9
SWITCH B1-2-4 2-4 NC 4-12 1-4-6 2-6-7 NC NC NC
C4-5 4-5 4-7-11 4-5-7 NC 4-7 4-11 4-11 4-5
D2-8-9 2-3-8 3-8 8-12 6-8 2-6-8 3-8 8-9 8-9
E3-5-12 3-6-12 3-7-12 3-8-12 3-8 3-8 3-8 12-8 12-8
F4-6-7-8 4-5-7-8 4-5-6-8 4-5-6-7 4-5-6-7f 4-5-6-7 4-5-6-7 4-5-6-7 4-5-6-7
GNC NC NC. 5-6 5-7 5-8 578 5-8 5-8
H4-6-7-8 6-7-8 4-6-7-8 4-7-8 4-6-8 4-6-7 4-6-7 4-6-7 4-6-7
I
1) Entries are numbers of those switch contacts which are connected together by the rotors at the particular position.
NC means no connection.
2) On schematic diagram, all switch wafers shown In the maximum counter-clockwise position (AUX) as seen from the front
or shaft end.
2AMPS. 117 VAC 117 VAC. 250 WTAPE SPEAKER CONNECTIONS AUX. TUNER MIC TAPE MAG. PHONO
II II O®(D(D(D ooooo oo
SWITCHED OUT 16 84G. TV HEAD LO HI
MODEL MF-32
30 WATT HIGH FIDELITY
INTEGRATED AMPLIFIER
TOP VIEW
V-5
EL84/6BQ5 111JEL84/6BQ5
V-8
EL84/6BQ5 11
V-4
''-7
11EL84/6B05 Ezll Q
V-l
oEC9O/6C4Q ecS?c4 0IS. 0
ECC83/12AX7 ECC83/12AX7
FRONT
OPERATES FROM IITV
50/6C CYCLE AC LINE
POWER CONSUMPTION:
140 WATTS
ELECTRONIC INST. CO.. INC
33-00 NORTHERN BLVD..
L. I. CITY «. N. Y.
10

Stock^
22517
20039
23014
22507
22508
20048
22515
22518
22514
22532
22547
22521
22548
22536
20024
23017
22509
20043
23016
24005
91005
92000
50014
50011
50016
29751
10435
10417
10407
11526
11533
10430
11527
11525
11511
10410
11518
10428
10449
18038
10416
18034
18033
10421
18039
10400
10900
11546
10412
11542
11547
10432
19009
10422
10447
^10853
r14601
60050
62000
32008
30021
54500
54000
54003
54013
81134
REPLACEMENT PARTS LIST
\
Sym, Description Am't.
Cl,
2
cop., disc., .025mfd (25K or 25, OOOmmf), GMV 2
,03,14.18. COP., mold^. .lmfd400V 3
C4,21 cop., elec., lOmfd, 6V 2
C5,10 cop., disc., .0022mfd (2. 2K or 2, 200mmf), 10% 2
C6 cop., disc., .0033 mfd (3. 3K or 3,300mmf), 10% 1
C7 cop., molded, .033 mfd, 20% 1
C8,ll cop., disc., 500 mmf, 10% 2
C9 cop., disc., .0027 mfd (2. 7K or 2, 700 mmf), 10% 1
C12 cop., disc., 850mmf, 10% 1
C13,17 cop., disc., .0015 mfd (1.5K or 1,500 mmf), 10% 2
C15,19 cop., disc., .015mfd (15K or 15, OOOmmf), 20% 2
C16 cop., disc., .001 mfd (IK or 1,000 mmf), 10% 1
C20 COP. ..disc.. .009 mfd f9K or 9, OOOmmf), 10% 1
C22, 23, cop., disc., 25 mmf, 10% 4
24,28
C25, 26 cop., molded, .022 mfd -600V 2
C27 cop., elec., 300mfd, 25V |1
C29 cop., disc., lOOmmf, 10% 1
C30 cop., molded, .03 mfd, 600V, 20% 1
C31,33 cop., elec., 30 mfd, 400V, 2^
C32 cop., elec., 20“40“40mfd/400“350“350V .
FI fuse, 3A 1'^
11 pilot light
Jl,^3,8 {ack, single phono 4v^
J4"5,6-7 jock, dual phono ly'
J9,10 outlet, convenience 2V'
PCI printed circuit l'^
Rl,2, res,, 150KQ (brown, green, yellow, silver) 1/2W,± 10% 2>/
R3 res., 220KQ (red, red, yellow, si Iver) 1/2W,± 10% 1V'
R4,5 res., IMQ (brown, block, green, si Iver) 1/2W,±10% 2/
R6,7 res., 200KQ (red, block, yellow, gold) 1/2W, ±5% 2^
R8 res., 1.2KQ (brown, red, red, gold) 1/2W, ±5% 1
R9 res., 4.7KQ (yellow, violet, red, silver) 1/2W,±10%
R10,12,14 res., lOOKQ (brown, block, yellow, gold) l/2W,i5% 3
Rll res., 15CKQ (brown, green, yellow, gold) 1/2W, ±5%
res., 560KQ (green, blue, yellow, gold) 1/2W, ±5% 1/
R13 1\/
R23 res., lOOKQ (brown, block, yellow, silver) 1/2W,±10% 1%/
R15 res., 2.2MO (red, red, green, gold) 1/2W,±5% 1
R16 res., 47KQ (yellow, violet, orange, silver) 1/2W,±10% !
R17 res., 5.6KQ (green, blue, red, silver) 1/2W,±10% 1^'
R18 pot., 500Kn, audio toper (volume) 1^
R19 res., 15KQ (brown, green, orange, si Iver) 1/2W, ±10% 1^
R20, S4 pot,, 500KQ, linear taper, CT (treble)- on-off switch
R21 pot., IMQ, linear taper (bass) 1
R22 res., 6.8KQ (blue, grey, red, si Iver) l/2W,al0% 1/
R24,PC2 pot., 500KQ, 2taps, linear (compentrol)
R25, 30 res., lOKQ (brown, black, orange, si Iver) l/2W,xlO% 2v' •
R26 res., 330 Q(orange,orange, brown) 2W, ±20% IV
R27 res., 33KQ (orange, orange, orange, gold) 1/2W,±5% 1
R28,33>34 res., 330KQ (orange, orange, yellow, si Iver) 1/2W, ±10% 3V'
R29 res., 1.6KQ (brown, blue, red, gpid) 1/2W,±5% 1V
R31,32 res., 82KC2 (grey, red, orange, gold) 1/2W,±5% 2-y
R35,36 res., IKQ (brown, black, red, si Iver) 1/2W,±10% 4V
37,38
R39 pot., lOOQ (hum adjust) 1^
R40 res., 68Kfi (blue,gfe/, orange, silver) 1/2W,±10% iv'
R41 res., 39KQ (orange, white, orange, si Iver) 1/2W,±10% K
R42 res., lOKQ (brown, black, orange, si Iver) 1W,±10% 1
R43 res., 80 5W, ±5% 1
SI switch, selector 1''
S2,3 switch, slide (rumble, scratch) 2v
T1 transformer, output IV
T2 transformer, power W
TBl terminal board, 4post 1*^
TB2,3 terminal strip, 1post left 2v'
TB4,8 terminal strip, 2post 2'-
tB5, 6, 7terminal strip, 1post left w/ground 3
shield, top with spado bolts 1
Stock^ Sym. Description Am't.
54006 TB9 terminal strip, 3post2rlght 1
54017 TBIO terminol strip, upright 1post right 1
54001 TBll, 12 terminal strip, 1post right 2
90034 VI,
3
tube, 12AX7
90051 V2,4 tube, 6C4
90039 V5^ 6,7,8 tube, EL84
90038 V9,10 tube, EZ81 2J
97800 XFl fuse holder
97712 ,XII pilot assembly 1V
97027 XVI,
3
socket, 9pin min. top mount 2
97033 XV2 socket, 7pin min. top mount 1
97024 XV4 socket, 7pin min. bottom mount 1''
97025 XV5,6,
7,a>9,io
socket, 9pin min. bottom mount 6V
40000 nut, hex, 6“32 x1/4 48
40001 nut, hex, 3/8"32 x1/2 6
40007 nut, hex, 4-40 x1/4 20
40008 nut, hex, 8*32 x1/4 14
40016 nut, hex, 1/2-24 w/slot It^
40026 nut, tinnerman, 8“32 6
40027 nut, tinnerman, angle bracket
screw, 6“32 x1/4 Bd.H.
2
41000 46 .
41003 screw, 8"32 x3/8 Bd.H. 8
41016 screw, 4-40 x1/4 Bd.H. 22
41027 screw, ^4 x3/8 R.H. brass wood screw 2V'
41028 screw, 8~32 x1R.H. 2
41045 screw, ^6 P. K. x1/4 brown 4
41046 screw, 8“32 x3/8 Bd.H. brown 4
41047 screw, ^8 P. K. x5/16 Bd. H. 6
42000 washer, lock, 3/8 6
42002 washer, lock, ^6 48
42007 washer, lock, ^4 22
42008 washer, lock, ^8 14
42029 washer, rubber, 1/2 ID (fuseholder)11
42032 washer, flat, ^8, 7/16 O.D. 2
43000 lug, ground, ^6 3^
43001 lug, pot, ground, 3/8 3
43004 lug, solder, ^8 4
43006 luo, ground K
46000 grommet, rubber 1'^
46006 feet, rubber A^
50012 Insulator, bckellte 2V
51006 plug, phono RCA 7V
53007 knob, round 5^
57000 line cord
58004 wire, hook-up length
58300 spaghetti length
58301 tubing, heavy length
58408 shielded coble, 1cond. length
58412 shielded cable, 3cond. length
58501 wire, bore, ^22 length
80052 panel IV
81108 chassis 1^
81109 bottom plate 1^
81110 bracket, left Ivr
81111 bracket, right. 1''
81112 perforated screen 1V
81113 shield 1*^
81114 bracket, switch iv
81116 bezel
81903 cable clamp (j)
89215 label, rear layout 1V
89216 label, tube layout 1V'
97300 tube shield 2V
97301 tube shield 1V
97710 jewel l'^
66060 manual of instruction (wired) IV'
66309 manual of instruction (kit)
11

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