Eico HF-14 User manual

general description
general
The EICO HF-14 it a14 waft high fidelity basic power
amplifier employing two EL84 output tubes in push-pull
and ahigh quality output transformer. The high power
sensitivity of these remarkably fine tubes eliminates the
necessity for additional driver stages, permitting the use
of a large amountof inverse feedback with a highstability
margin. The lower operating voltages required and the
use of EZ81 rectifier tube having a warm-up characteris-
tic exactly matched to the output tubes, result in apower
supply of exceptional reliability as well as extended out-
put tube life. Filter electrolytics and the rectifier oper-
ate well below maximum ratings and voltage surges at
starting are eliminated.
The HF-14 has been designed to maintain Its excellent
characteristics under speaker load (Including electrostatic
types) as well as the resistive load normallyused for test-
ing. Phase corrections have been provided at both ex-
tremes of the audio spectrum to insure stability under all
conceivable conditions and to insure that variations In
components and construction will not <dfect the perfor-
mance. Stability is maintained on all speaker taps with
loads ranging from zero to infinity. Overload character-
istics are excellent and theHF-l4wiil notexhlbit bounce
or flutter under pulsed conditions.
TheHF-14can be operated from any preanpl ifier control
unit. Apower take-off socket is provided for powering
the EICO HF-65AorHF-6lApre«nplifier control. Other
features include apanel mount fuse holder, switched and
unswitched convenience outlets, and heavy gauge cad-
mium plated steel chassis finished in bdied enamel,
SPECIFICATIONS
Rated Output Power;14 watts continuous, 28 watts peak.
1M Distortion (60cps &7kc at 4; 1): 1.7% at 14 watts, 0. 33% at 26 watts, 0. 1%at 4watts.
Harmonic Distortion ;8watts less than 1% from Me to lOkc.
10 watts: less than 1% from 40c to lOkc.
14 watts: less than 1% from 50c to 5kc.
20c distortion: 2% at 4. 2watts.
Transient Response: excellent square wave reproduction (4usec rise time); negligible ringing, rapid settling on lOkc
square wave.
inverse Feedback: 20db Tubes: 1- ECCB3/I2AX/, 2- bLB4, 1-fcZUI
Stab ili ty Margin
:
12db Power Source: 117 volts, 60cps.
Damping Factor: above 8, 20cp$ to 20kc.
Sensitivity :1. 25 volts for 12 watts output.
Hum; 90 db below rated output
Speaker Connections: 4, 8, and 16 ohms.
1
Power Consumption
:
65 watts
Size: HWD: 33/4” x12” x4".
Shipping Weight: 10 lbs.

mechanical installation
GENERAL
a) HEAT DISSIPATION (VENTILATION): Incommonwith
Other electronic equipment, the Model HF-14produces a
great deal of heat In norma! operation. Unlew contin-
uous and adequate air. flow Is obtained around the heat
produclngelementj, these elements will overheat and their
useful life will begreatly curtailed. Adequate ventilation
will be provfded if the amplifier is Installed in an open-
back console provldedthat thetopofthe amplifier is spac-
ed at least two inches be few 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. Al dn alternate, holes may be provided
In the sides, bottotn,or topof the cabinet. The Important
thing to remember Is that effective ventilation requires
provision for cool air to enter at the bottom and to leave
at the top.
If the amplifier is not installed In aconsole, It should be
situated preferably on an open surface. An attractively
finished matching cover for the Model HF-14 Is available
which will provide a"finished 11 appearance as well as
protection when the amplifier Unot installed in aconsole.
Four rubber feet are also provided so that the amplifier
will not mar the surface of furniture on which It is placed.
b) ACCESSIBILITY TO PARTS: Tubes are the most fre-
quently replaced Items In electronic equipment. If the
amplifier is placed in aconsole, sufficient space should
be allotted to reach and remove any tube in the ampli-
fier. Furthermore, Input and output terminals of the am-
plifier should be accessible to permit easy Interchanging
of system components for comparison. If antennas are
strung around the back of the console in which the ampli-
fier is installed, arrange them so they will not interfere.
c) ELECTRICAL ISOLATION: To realize the full benefit
of having apower amplifier physically separate from the
preamplifier-control unit and/or tuner, the power ampli-
fier should be placed at least one foot away (more if pos-
sible) from either or both of these units.
d) ACOUSTICAL ISOLATION: If amplifier and speaker
are installed In the same cabinet, provide sufficient sep-
aration to minimize mechanical speaker vibration reaching
the amplifier. The minimum separation is about one foot.
CONSOLE MOUNTING
Having determined aproper location for the amplifier In
the particular console, the correct procedure for mounting
the amplifier chassis Is as fellows: a) If the rubber feet
have been inserted In the bottom plate, remove them (pry
out with athin screwdriver), b) Remove the 6screws
which fasten the bottom plate to the chassis, c) Place the
bottom plate (bumps feeing up) at the location on the shelf
or other mounting surface In which It is desired to mount
the amplifier. With asharp pencil, placed with its point
directly against the edge of the lowersurface of the bot-
tom plate, draw the outline of the bottom plate on the
shelf and also mark the positions of the four outer holes,
d) Remove the bottom plate and drill each of the marked
holes on the shelf to adiameter of 1/4". e) Refasten the
bottom plate to the chassis, with 2 #8x3/8 screws pre-
viously removed, using the holes at the center, f) Re-
place the chassis on the shelf, positioning It exactly In
the outline previously drawn, g) 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 holes. These
screws engage the stamped nut over each hole In the chassis
flange and when tightened secure the chassis to the shelf.
electrical installation
POWER
A) POWER REQUIREMENTS: The EICO Model HF-14 re-
quires 65 watts at 110 to 120 volts, 60 cycles AC.
b) REMOTE SWITCHING: The EICO Model HF-14, al-
though not privlded with its own ON-OFFpower switch,
mounted on the chassis. Pins 6and 7of the octal socket
are internally connected to the ends of abreak In one
power transformer primary lead and are externally con-
nected together by ajumper in amole octal plug Inserted
in the octolsocket. When this male plug Is removed, pins
6 and 7may be brought out to an external AC switch,
usually In apreamplifier unit. This Is one of the connect-
ion functions accomplished with the octal plug-ond-cable
attached to the EICO HF-65A and HF-61A preamplifier-
control unit. If the HF-14 power amplifier is being used
with a self-powered tuner-preamplifier, the octal fur-
nished with the HF-14remains inserted in the octal socket
(to connect the primary of the power transformer to the
AC line and to ground one side of the filament winding)
and the line cord of the HF-14 Is Inserted in aswitched
117VAC convenience outlet In the control unit. Note:
When using aself-powered preamplifier -control unit,
touch one end of awire to the preamplifier chassis and
occurs, remove the HF-14 line cord plug and ra-lnsert It
with the prongs reversed.
a) POWERING AUXILIARY PREAMPLIFIER: The some
octal socket provides all necessary filament and B+ vol-
tages fer operating an auxiliary preamplifier-control unit,
6. 3volts AC filament voltage, at 1ampere, may be ob-
tained from pins 1and 2i pin number4 on the socket sup-
plies 350 volts DC, at amaximum current of lOmllll-
amperes; and pin 3Is connected to ground. As stated
above, control of 117 volts AC line power to the power
z

amplifier, and indirectly, power for the preamplifier-con-
trol unit. Itself, is made available through the connections
to pins 6and 7. This arrangement Is exactly suitable for
powering theEICO HF-65A and HF-61ApreampIifler-con-
trolunit;all that need be done is to remove the octal plug
provided with the HF-14 from the octal socket and Insert
theocfal plug-and-cableaf the HF-65A in its stead. Note
that ajumper between pins 2and 3of the octal plug fur-
nished with theHF-14effectively grounds one side of the
filament winding; removal of the octal plug leaves the
filament winding floating. This arrangement is used be-
cause ahum balance control is connected across the fila-
ment leads in theEICO HF-65A preamplifier and the arm
of this control is returned to ground.
d) CONVENIENCE OUTLETS: When the HF-14 is used
with apreamplifier that takes power from it, such as the
EICO HF-65A, the convenience outlets of theHF-14will
be found useful. The outlet marked ”1 17VAC SW. 11 ("SW."
Is an abbreviation for "SWITCHED") Is "live" or "dead"
depending on whether the preamplifier power switch is
turned to ON or OFF; plug tuners into the outlet. The
outlet marked "117VAC" Is not switched and is "live"
whenever the HF-14 line cord plug is inserted in awall
outlet; plug arecord changer into this outlet in order to
protect the mechanism. When the HF-14 is used with a
self-powered preamplifier, such as the EICO HF-65A, nor-
mally the convenience outlets on the preamplifier will be
used. However, the HF-14 outlets may be used also, if
desired, in which case both of them will be "switched".
INTERCONNECTION OF COMPONENTS:
SIGNAL
a) PREAMPLIFIER -CONTROL TO POWER AMPLIFIER:
Single conductor, shielded cable must be used to Inter-
connect the preamplifier-control unit or tuner-preampli-
fier-control unit and the power amplifier. Unless the
source has a low impedcnce outlet, such as acathode
follower (with which up to 50ft. of cable can be used),
use the shortest possible connection; In any case, use a low
capacity type of shielded cable (as lowas 25 mmf capacity
per foot is available). Both ends of the cable must be
fitted with RCA type phono plug connectors.
b) SPEAKER CONNECTIONS: To connect your speaker
to the amplifier properly, you must know its rated imped-
ance, which is usually marked on the speaker or specified
In the manufacturer’s literature. Connect one speaker
leod to the terminal on the rear apron marked "G" and the
the rated speaker impedance (4, 8or 16 ohms). Plastic-
covered lamp cord may be used for distances up to 50ft.
with little power loss. For shorter distances, tv antenna
lead can be used, particularly if it Is desired to run the
speaker leod under arug.
If it is desired to use two similar or identical full-range
speakers of the same rated impedance (either 8or 16ohms
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 spoctum (woofer-tweeter combinations), in
which case across-over network it required which con-
nects to the amplifier with only one pair of leads.
INTERCONNECTION PROCEDURE
a) Make ail system interconnections before applying AC
power. Making or breaking interconnections while AC
power is applied will result in amomentary overload of
both the power amplifier and speoioersysiem with possible
damage to either or both.
b) If the EICO HF-65ApreamplifiercantroI unit (not self-
powered) has been obtained In kit form, remove ail the
jumper connections In the octal plug supplied wijh the
HF-Mand wire the preamplifier power take-off leads to
this plug as follows:
Color of Preamp. Lead Pin of Octal Plug Connected to
grey 6
grey 7
brown I
brown 2
red 4
black 3
Wired HF-65A preamplifiers will have the preamplifier
leads connected to the octal plugs in the table above.
c) If it is desired to use apreanplifier without apower
supply other them theHF-61AorHF-65A,the power tdee-
off leads of the preamplifier should be connected to the
HF-14 octal plug (after removing the jumpers) as follows:
Preamp. Power Leod Pin of Octal Plug Connected to
AC ON-OFF 6
AC ON-OFF 7
filament (6.3 VAC) 1
filament (6. 3VAC) 2
B+ 4or5*
ground 3
*If the preamplifier requires 350VDC, use pin 4; if the
preamplifier requires less than 350 VDC, use pin Sand
connect adropping resistor of appropriate value and vol-
tage rating from pin 4to pin 5of the octal sockets on the
ion requires 300VDC B+ voltage at 10 ma drain, the drop-
ping resistor will be required to drop the voltage by 50
volts (350-300 =50) at acurrent off 10 ma. By Ohm's Low,
the required resistance inohms is the voltage drop in volts
divided by the current in amperes or 50 volts/. 01 amp. —
5000 ohms. The power dissipated ir» the resistor in watts
is equal tothevoltagedropin volte multiplied by the cur-
rent in amperes or 50 volts x.01 emtp =0. 5watts. For
safety aresistor of double the wattage rating should be
used. Therefore, a 5000 ohm Iwatt resistor is required.
3

maintenance
CONTROL ADJUSTMENTS
a) The INPUT LEVEL ADJ. control I* Intended to protect the
speaker system from "blasting” should someone turn the
preamplifier-control unit level controls to full, by per-
mitting you to attenuate the preamplifier output signal by
any desired amount at the Input to the power amplifier
where It can not be “fiddled" with. Start by setting the
INPUT LEVEL maximum cotnter-elockwise (maximum at-
tenuation), using a screwdriver. Set the LOUDNESS con-
trol on your preamplifier to the maximum clodkwlse posi-
tion and the LEVEL control at the midpoint of Its range of
rotation. Turn your phonograph on and play on average
orchestral record. Then slowly ortate the INPUT LEVEL
ADJ. control clockwise until the music Is at normal (or
concert) listening level. This completes the adfustment,
which need not be repeated.
b) ON-OFF SWITCH: Should be used in ON position
when unit Is used with apreamplifier. It may be used as
apower on-off switch when the amplifier Is accessible.
TROUBLE-SHOOTING PROCEDURES
Your ampllflershould require little service except for nor-
ma! tube replacement. We recommend no substitutions
for the tube types used In this amplifier. The ELM, and
EZ81 types are distributed natlonallyby the Amperex Elec-
tronic Corporation (230 Duffy Ave., Hlcksvllle, LI.,
N.Y.)and Mullard Ltd. (International Electronics Corp.,
81 Spring St., N.Y. 12, N.Y.) If necessary, replace-
ments can be obtained directly from EICO.
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 In locating defective
components and to permit acareful, stage-by-stage check
of the amplifier. DC operating voltages are given both
at no signal and at asignal developing 14 watts output as
well as the corresponding Ike signal voltages.
To Isolate the source of unusual hum or noise in your system,
first turnoff the AC powerand then unplug the audio cable
connecting to the amplifier input. Then turn theAC power
on again and note whether hum or noise has decreased.
If It has, the fault is in the preamplifier or associated
equipment and measures should be taken to correct It os
described In the service notes for these units. If it Is de-
sired to provide agood building ground for your entire
system, run alead from under speaker connection terminal
“G" to acold water pipe. Do not connect such aground
wire to other components in the system.
If the trouble is no output or low output and the amplifier
is suspected, check AC signal voltages starting at the In-
put and working step-by-step toward the output, using a
sine-wave audio signal generator and aVTVM. Set the
Input signal to 1volt. The corresponding grid and plate
signal voltages for this input are indicated on thesehematic
diagram. This procedure should suffice to localize the
defective stage.
If the trouble Is at excessively distorted output, try tube
replacement, signal tracing or precede directly to voltage
and resistance measurements.
When the defective stage Is localized, precede to are-
sistance and voltage checkof the stage, using the data in
the Resistance and Voltage chat. Disconnect the ampli-
fier from the power line and discharge capacitors prior to
making any resistance check or removing the ELM output
tubes. Do not turn the amplifier on with anyof the output
tubes removed. ”
CHICKING ATYPICAL TUBE STAGE
1. Check tube.
2. Check plate and cathode resistors.
3. Check coupling 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 RI4, and filter capacitor, C8
for short.
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 R14.
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 $5. DO plus the cost
of parts replaced due to their being damaged In the course
of construction. NOTE: Before returning this unit, be
sure all ports are securely mounted. Attach atag to the
instrument, giving your home address and the trouble with
the unit. Pack very carefully in anigged container, u»-
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-
mentwill be made byexpress collect. Note that acarrier
cannot be held liable for damages in transit if packing
IN HIS OPINION, is insufficient.

VOLTAGE AND RESISTANCE CHART
TIME HN* DC VOLTS DC VOLTS
NO SIGNAL MWATTS AC VOLTS 0ke)
1.25 VOLTS INPUT
ECC0$/12AX7 1
VI 2
3
U3
6
105 102 10
001.25
0.9 0.9 1.13
Moment (4. 3VAC to pin 9)
222 215 9.5
112 105 10
105 102 9.5
1009.5
20 0 9.5
312.5 15 .1
445 fllamnt (6. 3VAC between!
4--
?335 320 6
8 0 0 9.5
9340 325 1B2
SHI
V4 1295 i
3340 325
445 filament (6. 3VAC between)
6
7295
8
All wHbqm and rvlitanca tee Mound to chmk. Voltages o»e otataUTnit
«M oMflK Input Impedatce VTVM. All rol.no Mounnol) ere mode
wllfc pin 3erf rtw EZ81 grouixUd except, of ooune, when the restitance to
gmuarf of pin. 2<md 8of the EZ81 is bolng choeW. Operating line voltage
at which voltage measurements arooiodo HII7volM AC, 60cfx. NOTti ALL
VOLTAGE &RESISTANCE VALUES MAY VARY NORMALLY BY *15*.
TROUBLE-SHOOTING CHART
SYMPTOM CAUSE
House power line fuse blows;
fuie, FI, remains intgct.
Fuse, FI, blows.
Any or all tube filaments not lit.
Short in line cord, J2, J3 or associated
equipment plugged info J2 or J3.
If the amplifier causes areplacement fuse to
blow with rectifier tube V4 removed, primary
or high voltage secondary windings of T2 are
incorrectly wired or shorted.
If FI does not blow after replacement (with
V4 removed), check for short In B+ circuits,
defective V4 and C8.
Open lead from 6.3 Vwinding of T2.
6. 3Vwinding of T2 open
DC voltage at V4 cathode (pin 3)
is incorrect as specified below.
-a) No voltageDefective V4.
C8 shorted internally or externally.
Connection to C8 broken.
b) High voltage Connection to center tap of h. v. sec. winding
of T2 open.
Output tubes V2 and V3 over-biased
or not drawing current.
c) Low voltage Excessive current drain in amplifier.
Defective V4.
5
RESISTANCE
UNIT OFF
3KKQ
I.8KQ
1630
160-2000
330KO
0
950
160KQ
950
REMEDY
Repair
Check and repair or replace.
Check and repair or replace.
Repair
Replace T2.
Replace
Replace or repair.
Repair
Repair
See trouble-shooting typical
stage.
See trouble-shooting typical
stage.
Replace

REPLACEMENT PARTS LIST
Stock* Sym. Detcrlptlon Ain't. Stock* Sym. Description
91000
50014
50016
10400
10431
11543
11527
10412
11538
14600
10406
62004
32005
30019
54001
54003
54002
90034
90039
90038
97800
97027
cop., dltc., !50mmf, *10%
cop., dite., .025mfd- 500V (25K of 25,000)
cep. ,dlfc. ,200 mm#, *10%
cop., elec., 50mfd-25V
cq>., dltc. ,47mmf, *10%
cop. ,sloe., 30-20-20mfd- 430V
cop., paper, .03 mfd -600V
fine, 2amp
|ack, tingle phono
outlet, convenience
lack, octal
pot., SOOKQ, audio
ret., lOKft, 1/2W, *10% (brown, black, orange, tilver)
re,., 470KQ, 1/2W, *10% (yellow, violet, yellow, tilver)
ret., 1.81UX 1/2W, *5% (brown, grey, red, gold)
ret., 100KQ, 1/2W, *5% (brown, block, yellow, gold)
ret., 330KO, 1/2W, *10% (orange, orange, yellow, tilver)
ret., 22KQ, 1/2W, ±5% (red, red, orange, gold)
ree., 1650; 5W, *5%
rot., 6800, 1/2W, *10% (blue, grey, brown, tilver)
•witch, tlide, DPST
Voutput
terminal Itrip, 1post right
terminal itrip, 2pott
terminal ttrlp, 1pott right w/ground
tuba, I2AX7
tube, ELB4/7I89/68Q5
tube, EZ81
futeholder
tocket, 9pin, lop mount
97025
40000
40001
40007
40008
40016
40017
41000
41003
41016
41028
42029
42000
42001
42002
42007
42000
42032
43000
43004
46000
46006
51006
51007
57000
58004
58300
58501
81165
81166
97300
66070
66319
ocket, 9pin,
nut, hox/6-32
nut, hex, V8-32
nut, hex, *4-40
nut, hex, *8-32
nut, for Futeholder
nut, tin., *8-32
terew, *6-32 xI/<|
.crow, *8-32 x3/8
terew, *4-40 x1/4
terew, *8-32 x1
wather, rubber for fuse
wather, lock, *3/B
wather, flat, *3/8
wether, lock, *6
wather, lock, *4
wather, lock, *8
wother, flat, *8
lug, *6
lug, *8
grommet, 3/8
feet, rubber
plug, phono
plug, octal
line cord
wire, hook-up
spaghetti
wire, bore, *22
bottom plate
tube thleld
manual rf Initruction (v
manual oF initruction (k
3
12
6

disc./
200mmf,±l
disc./
200mmf,±l
7
»san
hf-m
74
WATT
HIGH
FIDELITY
POWER
AMPLIFIER

CAPACITOR
COLOR
CODES
RESISTOR
COLOR
CODES

e®*
®S.-£
Ili
'fi «a
I-E g
.
ii -* i
S!J!
l-s U
S’_ I
s' JIs
3-5 -Sj
£2-8
§S$1
1^1
1
I
I
"S =£• t
*r OOE
2*It
Zfe il
.me *
•l-i s|
?I *-x
fNPI 'MO «N
82-* •-s*’?« «t
I|4ljl pl= .
f'» S!*'4 St s'*® o3£
-ii oio
it £>°-o -^*"8 «®«g«
=2°i 1»;
•g;§.|* i_J =J
eacE5f2> e>-5
>1T8Jvl 5
til i!li •1I1is
Oi=•* «:g- SH
5cvci"ISgi g
y.|| s.jS 8l-
:-,SS T5?1
5=®f |=
.£ Z.co®<-®o«j-o o“
a. c£ of »J2 »°--
cfi*g *e;-? s>
E“-
-8
>-t 001 ^PI-
11 ls*I«|l» II
O“K“ St'S? 8?s =»
c8u >le“6«'
gSi-5 g•E-c-a'
|cO.S-2 oefeo-
~£5*g E£|2
II ~
Hi
a.
voj 8-g s®|tL s£8
1
fsJs-* Si 2-sj si
J| Sg.=5 £S.£ S2-i S
IS-J ^
lili 1
1*1?i
!5»8[
•Hi -
t-s *?|
-0*00 -f.
“B.£S^
-2 -8
HI!
Sis sSsi
2-°» o®2"o
5s*c-g o*o
zlis li:
C£
P•oow§£
n^n«C8
y-2 ?c o a>
-S
Jir a, II ti
aa-2 c® o !
3|T £c-T 1
“*-8o«
ail til*