Eico HF-35 User manual

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TAMPLIFIER
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HF-35
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MODIl Hf -35
35 WATT
HIGH FIDELITY AMPLIFIER
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1

FEATURES
1. EF86 phenomenally low-noise, high gain, voltage
preamplifier*
2. Dtrec tcoup 1ing between vo Ito ge preamp] Ifler and phase
inverter to eliminate atime constant*
3* 6SN7GTB cathode-coupled ("long-tailed 11
)phase in-
verter for forced balance over the entire frequency and
dynamic range. Provides drive for the output stage from
equal and comparatively low impedances,
4* EL34/6CA7 output pentodes in apush-pull Ultra -Lin-
ear output stage,
5. Carefully balanced, extremely high quality wide-
band output transformer employing grain -oriented steel
and extensively interleaved windings, Asuperb high-
frequency roll -off characteristic permits achievement of
the virtually absolute stability sought for in the design.
The transformer is supplied fully potted and with 4,8,
and 16 ohm output taps.
6, Heavy duty power transformer with reserve capacity
for powering any preamplifier*
7, Extra-rugged GZ34 rectifier tube with indirectly heat-
ed cathode to el iminate high starting voltage on the elec-
trolytic filter capacitors and to delay the application of
the full B+voltage to the amplifier tubes until they have
warmed up,
8, Input level control,
9- Fuse and panel mount fuse holder*
10* Standard octal socket provided for preamplifier power
take-off and remote on-off switching,
11, Switched and unswitched AC convenience outlets*
12, Heavy gauge steel chassis.
SPECIFICATIONS
Rated Output Power :35 watts continuous; 70 watts peak.
1MDistortion (60 &6000 cps at 4:1): below 1, 5% at 35 watts; 0* 15% at 20 watts*
Total Harmonic Distortion :below 0. 5% at any frequency from 2Gcps to 20kc within 1db of 35 watts.
Undistorted Sinusodlal Frequency Response: ±0. 5db 5cps to 60kc at lwatt level; ±0* Idb 20cps to 30kc atony level
from 1milliwatt to 35 watts; no peaking or raggedness outside audio range.
Square Wave Response s20 cps to 20kc essential/ undistorted; 3,5 micro-seconds rise time; no overshoot at any frequency
or power level nor visible rounding below 15ke*
Inverse Feedback; 20 db
Stability Margin ;18db
Damping Factor: above 10, 20cpsto20kc; 15 at lkc.
Sensitivity ^0. 43 volt for 35 watts out*
Hum: 90 db below rated output.
Speaker Connections: 4, 8, and 16 ohms*
Tubes 2- EL34/6CA7, 1- EF86/Z729, 1- 65N7GTB, 1-GZ34.
Power Source: 110-120 volts, 60 cycles; 130 watts; 3amp fuse*
Size: HWD: 7" x14" x8'1
Weight; 25 lbs.
2

REPLACEMENT PARTS LIST
Stock* Sjrm. Description Am t
20042 Cl cap-, molded, Q5mfd -4QQV, ±10% l
21509 C2 cap dsc, IQDmmF, ±10% l
23007 C. op ,lec,, 50mfd-25V 1
20044 C4 cap-, molded, 23 mid -400 V±0% 1
20040 C5, 7cap ,mo d, lmfd-600V, ±10% 2
22335 C6 cap., disc., l/Sjnmf, ±10% 1
22542 C8 cap ,dsc. r750mmF -10QQ V410% 1
22532 C? cap., disc., 05mfd,±!0% (l.SKor 1500) 1
24007 C10f11 cap, ,elec ,2 x 20 mfd -500 V2
23011 C12 cap. ,elec., 50mfd-50V 1
20043 C13 cap., maided, 03mfd-60QV 1
91005 FI fuse, 3amp i
MX314 J1 jock, single phono 1
500 UJ2, 3oat let, convenience 2
97032 J4 jack, octal l
16016 R1 pot. 1MQ, audi 1
1040G R2 res ,10KC1, 1, 2W, ±10% *(brown, black, orange, silver
)
1
11531 R3 las., 470KC1 1/2W, ±5% (yellow, violet, yellow, gold) 1
11527 R4 res,, I00KQ, 1/2W, ±5% (brown, block, yel low, gold) 1
11505 *5 res, 100 Q, 1/2W, ±5% (brown, black, brawn, gold) 1
115 0K6 res., 1138Q, i/2W,±5% 1
10407 R7 res., IMQ, 1/2W, ±10% (br wn black, green silver) 1
10416 R8 res. I5KQ, 1/2W, ±10% (brown, green, ange, liver) 1
10*19 R9 ra §2GKil, 1/ 2W, ±10% (red, lolet yellow, liver) 1
10652 R10, 19 res ,15KQ, 1W ±10% (brown, green, orange, silver) 2
11513 R11, 12 res. ,3KQ, 1/2W, ±5% (orange, black, red, gold) 2
11600 R13 f*>., iBKQ, 1W, ±5% (b- own, grey, orange, gold) \
11601 ft 1
4
res. ,28. 75KQ, IW, ±5% 1
1602 R15 res., 33KQ, IW, ±5% (orange, orange, orange, gold) 1
10444 R16, 17 rt»s., 120KQ, 1/2W, ±10% (brawn, red, ye Ilow, silver) 2
14305 R13 res., 235a 1QW, ±10% 1
10432 R20 23 res. H1KQ, 1/2W, ±10% (brown, black, red, silver) 2
14306 *22 res. ,50a 10W, ±10% I
32004 11 tran-famer, output i
30020 T2 Irons fa riner, power i
54500 TB1 terml no! board, 4post l
54003 TB2, 5terminal strip 2post 2
54004 TB3 terminal strip 2post w/graund 1
54006 TB4 terminal strip, 3post, 2right 1
54001 TB6 terminal strip, 1pail right 1
90042 VI tube, EFB6 1
90041 V2 tube, 6SN7 1
Stock* Sjm. Description Am
900*0 V3,4 tube, EL34 2
90044 V5 tuDe, 5U4G& 1
97600 XF1 fuse holder 1
97027 XV 1socket, 9pm miniature 1
97032 XV2-5 socket, octal 4
40000 nut, *6 32 he* 21
40001 nut, */8~32 hex 1
40005 nut, *10-24 hex 10
40007 nut, *4-40 hex 2
40016 nut, *1/2-24 hex 1
40017 nut, *8-32 tinne man 10
41000 screw, *6-32 *1/4 Bd, H. 21
41003 screw, *8-32 x3/8 10
41006 screw. *10 24 x3/6 Bd. H. 10
41016 screw, *4-40 x1/4 2
41028 screw, *8-32 x14
42000 washer, *3/8 lock I
42001 washer, *3/9 Flat 1
42002 washer, *6 lack 20
42004 washer, *10 lock 10
42007 washer, *4 lock 2
42011 washer, *10 flot 10
42029 weeher. rubber 1/2 1Dl
42032 washer, *9 flot 4
43000 lug, *6 ground 1
430 2lug, *10 2
46000 gommet, 3/3 rubber 1
46006 bumper rubber 4
51006 input plug l
51007 octal plug and hood 1
57000 line card •l
50004 wire, hook-up length
58300 spaghetti length
58501 wire, bore *22 length
81097 bottom pla e1
ens7 chass t1
81903 coble clamp 1
97300 tube shield t
66069 manual of instruct an (wl. d) t
66310 manual of instruction (kit) 1
1Resistors wh eh gre Indicated on the part* Kst and/or in lha cnitrudion tm
being color- coded may sometimes not be co or -coded because of varying pocticu
between resistor manufacturer*, When this lithe case the value of the rt»‘sto, will
be found printed on the body, which will be of asolid color.

VOLTAGE AND RESISTANCE CHART
DC VOLTS DC VOLTS AC VOLTS (lkc) RESISTANCE
TUBE PIN* NO SIGNAL 35W OUT 35W OUT UNIT OFF
EF86/Z729 155 55 0.35 740Kn
200 0 0
31.2 1.2 0.35 1.2KO
4& 5filament (6, 3VAC between) -
648 48 5.3 500KO
700 0 0
B1.2 1.2 0.35 1.2KO
9000.4 IMegO
6SN7GTB 345 45 .0034 1.3Meg ft
2330 320 23 43KO
363 63 2.4 18KO
448 48 5.3 400KO
5320 320 23 42KO
663 63 2.4 18KO
7&8 filament (6,3V AC between)
EL34/6CA7 i33 36 0.1 2350
(both) 2&7 filament (6. 3VAC between) -
3450 440 265 2050
4450 440 110 1150
50023 120KO
6 0 023 I20KO
833 36 0.1 2350
GZ34 1-
2
ofilament 470 (5,0V AC to pin 8—remove tube to measure) above 200KO
o
4393 500
5--
6393 500
7-mm
8filament &cathode 470 465 above 200KO
All voltages and resistances are measured to chassis with the Input level control set maximum. clock-
wise (full gam). Voltages are measured with ahigh impedance VTVM. All resistance measurements
are made with pin 8of the GZ34 grounded except, of course, when the resistance to ground at pins
2and 8of the GZ34 Is being checked. Operating line voltage at which voltage measurements are
made is 117 volts AC, 60 eps. NOTE? ALL VOLTAGE &RESISTANCE VALUES MAY VARY NOR-
MALLY BY ±15%*
8

TROUBLE-SHOOTING CHART
SYMPTOM CAUSE REMEDY
House power line Fuse blows; Short in line cord, J2, J3 or associated Repair
fuse, FI, remains intact. equipment plugged into J2 or J3.
'
.
Fuse, FI, blows* If the amplifier causes areplacement fuse to Check and repair or replace*
blow with rectifier tube V5 removed, primary
or high voltage secondary windings of T2 are
Incorrectly wired or shorted*
If the amplifier does not cause FI to blow Check and repair or replace*
when V5 is out of the socket, but does
cause FI to blow when V5 is placed back
In the socket, then check for short In B+
circuits, or defective V5, CIO, CII *
V5 filament not lit. Incorrect wiring of ft!, leads to V5 socket*
5V HI. winding of T2 open.
Repair
Replace 12.
Any or all other tube filaments
not Ilf.
Open lead from 6* 3Vwinding of T2,
6. 3Vwinding of T2 open*
Repair
Replace T2.
DC voltage at V5 cathode {pin 8)
Is incorrect as specified below*
a) No voltage* Defective V5,
CIO shorted internally or externally*
Replace
Replace
Connection to center-tap of high-
voltage winding of T2 is open*
Open R22.
Repair
Replace
b) Low voltage. C11 shorted Internally or externa My* Replace or repair
i'
Connection to C10 from pin 8of V5
is broken, or open CIO.
Repair or replace
Excessive current drain In amplifier. Repair
c) High voltage. Output tubes V3 &V4 over- biased
and not drawing current*
V3 or V4 defective.
Repair
Replace
Open R9 or RIO,
Shorted R22,
Replace
Repair or Replace
7

FINAL STEPS
You have now completed the assembly and wiring of your amplifier. When
you have completed the following steps your amplifier wi 1 1 be ready for use.
1} To catch any wiring errors. It is suggested that the entire wiring be checked
polnt-by-polnt 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)*
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 tubes VT through V5 in their correct sockets and the fuse in the fuse
holder* Place ashield over VI
.
4) Insert the octal plug into octal socket J4,
5) IMPORTANT: BE SURE TO MAKE THE FOLLOWING RESISTANCE CHECKS
BEFORE CONNECTING TO THE AC LINE: Check for acolddc resistance of
at least 1.2 ohms across the AC pul gf check for aresistance of at least 45 ohms
between ground and pins 4and 6of XV5; check for aresistance of at least
200Kohms between pin 8 of the rectifier tube V5 and ground. Allow suffi-
cient time for the electrolytic capacitors to be charged by the ohmmeter bat-
tery In this last measurement. These measurements const itute areasonable check
of the powersupply components and wiring before applying power. If you fall
to obtain these resistance values/ do not proceed to the next step until the
cause Is discovered and the condition remedied. If the measurements are sat-
isfactory, proceed to CONTROL ADJUSTMENTS in the MAINTENANCE sec-
tion of the book* DO NOT CONNECT TO THE AC LINE until you have com-
pleted the preliminary BIAS ADJ* and BALANCE ADJ. control adjustments,
at which point you will be Instructed to do so. When you have completed the
CONTROL ADJUSTMENTS, proceed to the step following this one, after
having disconnected the amplifier from the AC line.
6) Press aspeed nut In place over each hole on the bottom flange of the chassis
(see Fig. 6),
7) If the amplifier is not going to be fastened to some surface ,insert the rubber
feet in the openings provided In the bottom plate and mount the bottom plate
on the chassis, using 10 ^8^32 X3/8" screws. Do not use the 1" long screws
for this purpose (possibility of shorting input jack). If the amplifier is to be
fastened to asurface, the Feet will not be used and the bottom plate will be
required as atemplate before it is attached to the amplifier.
8) Read theMECHANICAL IN5TALLATION and ELECTRICAL INSTALLATION
sections of the instruction book coreful ly, and Install and connect the amplifier
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 where if w! 1 1 be placed in operating condition for $5.00
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 that show 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 Is 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.l. C. 1, New York. Re-
turn shipment will be made by express collect. Note that the carrier cannot be
held liable for damages In transit If packing, [N HIS OPINION, Is insufficient.

nc
1. ()Fig. 5. Connect the white and the red-yellow leads from hole "W"
to ground lug "E" (C).
2. ( ) Fig. 5, Connect the black lead From hole "X" to J3-2 (C).
3. ( ) Fig. 5, IF your line voltage Is normally below 122 volts, connect
the red-black lead to XF1-I (C), and tape up the green-black lead as shown.
IF your tine voltage is normally above 122 volts, connect the green -black lead
to XFl-1 (C) and tape up the red-black lead as shown.
4. (}Fig. 5. Cut both leads on a,Q3mfd (orange, black, orange, black, blue)
capacitor, C13, to 1". Connect from XF1-1 (52) to ground [gg 11 E" (53).
5. ()Fig. 5. Cut both leads on a750 mmfcapacitor, CB to 3/4". Connect
one lead to TB5-2 (C) and the other to XV3-3 (52).
6. ()Fig. 5. Connect a511 piece of yel low wire from XV4-8 (C) to XV3-1 (C),
7. ()Fig, 5. Connect a51/2" piece of green wire from TB5-1 (S2) to
XV4-6 (C).
8* ()Fig. 5. Connect a41/2" piece of red wire from TB5-2 (S3) to J4-8 (C).
9. ()Fig, 5, Twist the two green leads from hole "X" on the power trans-
former T2, as shown. Connect one lead to XV4-7 (C) and the other lead to
XV4-2 (C).
10. ()Fig.5. Connecta 11/4" piece of bare wire from XV4-2 (S3) to J4- 1(5 1).
11. { ) Fig. 5. Connect a3" piece of brown wire from XV4-7 (S3) to J4-2 (5 1).
12. {)Fig. 5. Connect a3/4" piece of bare wire from J4-3 (SI) to ground
lug nB" (SI) on J4.
13. ( ) Fig, 5. Cut both leads on a15KQ (brown, green, orange, silver) 1watt
resistor, R19, to 1/2". Connect from J4-8 (S2) to J4-4 (SI).
14. ()Fig. 5, Connect a11/2" piece of bare wire covered with a1" piece
of spaghetti from J4-6 (SI) to J3-1 (C).
15. ( ) Fig. 5. Connect a31/2" piece of yellow wire from J4-7 (SI) to
J2-1 (C),
16. ()Fig, 5. Connect a41/2" piece of brawn wire from J3-1 ($2) to
XF1-2 (SI),
17. ()Fig. 5, Connect a11/4" pieceof bare wire from J2-2 (C) to J3-2 (S2).
18. ( ) Fig. 5. Connect a1/2" pieceof bare wire from XV4-8 (C) to XV4-1 (51),
19. ()Fig, 5. Connecta 1/2" piece of bare wire from XV3-8 (SI) to XV3- 1(C).
20. ( ) Fig. 5. Cut one lead on the 235Q resistor, R18, to 11/2" and the
other lead to 3/4". Cover the longer lead with a11/4" piece of spaghetti
and connect to XV4-8 (S3), Connect the other lead to ground lug "D" (C).
Dress this resistor flat against the chassis* Dress all leads away from this resistor,
21* ( ) Fig, 5, Cut both leads on a50 mfdf50 volt, electrolytic capacitor
C12 to 11/4", Connect the positive (+) lead to XV3-1 (S3) and the negative
lead to ground lug "D" (S2 )*
22, ()Fig, 5. Cut all leads on two 1KQ (brown, black, red, silver) resistors,
R20andR21, to 1/2", Connect one resistor, R20 from XV3-6 (C) to XV3-5 (SI)
and the other resistor, R21 from XV4-6 (C) to XV4-5 (SI).
23, {)Fig. 5. Cut all leads on two 120KQ (brown, red, yel low, silver) resis-
tor, R16 and R17, to 3/4", Connect one res istor, R16, from XV3-6 (S3), to
ground lug "F1atXV3{52). Connect the second resistor, R17, from XV4-6 (S3)
to ground lug "G"at XV4(51), In both cases, be careful not to burn the wires
passing near the ground lugs,
»
24, {)Fig. 5. Pass the tinned leads from the line cord through the grommet
at the rear of the chassis. Make aknot 3/4" from the end of the solder lead, so
that the line cord cannot be pulled through the grommet. Connect one tinned
lead to J2-1 (52) and the other tinned lead to J2-2 (S2),

1. {}Fig. 4. From hole "Y" of output transformer Tl, twist the red and
red-yellow leads together. Connect both leads to TB4-1 (C).
2. ( ) Fig. 4, From hole "Y fl of the output transformer Tl, twist the brown
and brown -yellow leads together. Connect the brown lead to XV3-3 (C) and
the brown-yellow lead to XV3-4 (SI),
3. {)Fig, 4. From hole trYMof the output transformer Tl, twist the blue
and blue -ye Ilow leads together. Connect the blue lead to XV4-3(Sl)and the
blue -ye How lead to XV4-4 (SI).
4. ( ) Fig. 4, Connect a41/2" piece of green wire from TB4-2 (C) to
XV2-4 (C).
5. ( ) Fig. 4. Cut both leads on alOOromf disc capacitor, C2, to 1/2",
Connect from TB4-2 (C) to TB4-3 (C)
6. ()Fig, 4, Cut both leads on a1G0KO (brown, black, yellow, gold) resistor,
R4, to 3/4". Connect from CI1-B (C) to TB4-2 (S4).
7. ()Fig. 4* Cut both leads on a15Kf3 (brown, green, orange, silver) 1/2N
resistor, R8, to 3/4 11
.Connect from Cl 1-B (C) to TB4-3 (S2).
8. ( ) Fig. 4. Cut both leads on a270KQ (red, violet, yellow, silver) resistor,
R9, to 1/2", Connect from C1 1 -A (C) to C11*8 (S4).
9. ()Fig, 4, Connect a5Mpiece of red wire from C10-A (C) to T85*2 (C).
10- ( ) Fig. 4. Connect a6" piece of red wire from C10-A (C) to TB4-I (C),
11, ( ) Fig, 4, Connect a5" piece of red wire from Cl l-A (C) to TB6 (C),
12, ( ) Fig, 4. Cut both leads on a15KQ (brown, green, orange, silver) 1watt
resistor, RIO, to t/2". Connect from TB4-1 (S4) to Cll-A (C),
13, ()Fig. 4* Cur both leads an a28. 75KQ (red, grey, grey, gold) resistor,
HI 4, to 3/4"; Connect from XV2-5 (C) to C11-A (S4)+
14. ()Fig. 4. Connect aI1/4 11 piece of bare wire covered with a1" piece
of spaghetti from XV2-6 (SI) to XV2-3 (C).
15. (!Fig. 4. Cut both leads on aIMft {brown, black, green, silver) resistor,
R7, to 1/2". Connect from XV2-1 (C) to XV2-4 (S2).
16. ()Fig. 4. Cut both leads on an 18KQ (brown, grey, orange, gold) resistor,
R13, to 3/4"* Connect from XV2-3 (S2) to ground lug "F" (C) on XV3,
17. ()Fig. 4. Cut both leads on a 33Kfi (orange, orange, orange, gold)
resistor, R15, to 3/4". Connect from TB6 (S 2) to XV2-2 (C).
18. ()Fig. 4. Cut both leads on a,25mfd (red, green, yellow, white, yellow)
capacitor, C4, to 1". Cover one lead with a3/4" piece of spaghetti and con*
neat to XV2*1 (S2), Connect the other lead to ground tug "C (SI) at CIO-
19. ( ) Fig. 4, Cut both leads on a-1mfd (brown, block, yellow, white, blue)
capacitor, C5, to I". Connect from XV2-5 (S2) to XV3-6 (C).
20. ()Fig. 4. Cut both leads on a,1mfd (brown, black, yellow, white, blue)
capacitor, C7, to 11/2". Cover each lead with aI1/4" piece of spaghetti.
Connect from XV2-2 (52) to TB5-1 (C).
21- ( ) Fig. 4, Twist the two red leads from hole Tof power trcnsformer
T2, and run along the chassis as shown- Connect one red lead to XV5-4 (SI)
and the other red lead to XV5-6 (SI),
22. ()Fig. 4, Twist the two yellow leads, one from hole "W" and the other
from hole "X", of the power transformer T2, and run along the chassis as shown.
Connect one yellow lead to XV5*2(S 1) and the other yellow lead to XV5-8 (C),
23. ()Fig. 4, Cut both leads on a5GQ, lGwatt,wire wound resistor, R22,
to 3/4". Cover each lead with a1/2" piece of spaghetti. Connect from XV5*8
(52) to C10-B (C).
24. ()Fig. 4. Connect a11/4" piece of bare wire from CIO-B (S2) to
C10-A (S3),

CHASSIS WIRING
L()Fig* 3, Connect al 1 /2'* piece of bore wire from IB 1-4 (C) to ground
lug "A" (S}-\ (S I)
2. ( ) Fig. 3. Connect a6" piece of black wire from TB2-2(C) to TB3-1 (C).
3. ()Fig. 3. From the output transformer TI, connect the leads from hole
ll Z" as follows: black to TB1-4 (S2), white (or slate) to TB 1-3 (C), green to
TBl-2 (SI) and yellow to TB1-1 (C).
4. ()Fig- 3. Cut all leads on two 3KQ (orange, black, red, gold) resistor,
R1 1and R12, to 3/4". Connect one resistor R1 1fromTB2-I (C) to TB2-2(C) and
the second resistor from TB1-1 (C) to TB2-1 (C).
5* ( ) Fig. 3* Cut both leads on a.Q0I5mfd (L5K or lSQOmmf) disc capaci-
tor, C9 to 1". Cover each lead with a3/4JI piece of spaghetti. Connect from
TB I-3 (52) to TB2-1 (S3),
6. ( ) Fig, 3, Cot both leads on oI75mmf disc capacitor, C6, to 3/4". Con-
^nect from TB1-1 (S3) to TB2-2 (S3).
7. ()Fig, 3. Cover a1/2 'piece of bare wire with a1" piece of spaghetti.
Connect from TB3^1 (C) to TB3-3 (C),
8. ()Fig. 3. Connect a1/2" piece of bare wire from the center pin of
XVM0(SJ to XVI -7 (C).
9. {)Fig. 3. Cover a13/4" piece of bare wire with a11/4" piece of
spaghetti. Connect from XVI -7 (S2) to TB3-2 (C).
10. ()Fig, 3. Cut both leads on a1GQQ 5% (brown, black, brown, gold)
resistor, R5, to */2", Connect from TB3-1 (C) to TB3-2 (C).
11. ( ) Fig 3. Cut both leads on a1. 136KQ resistor, R6, to 3/4", Connect
from TB3-3 (C) to XV1-8 (C).
12. ()Fig. 3. Connect aI1/4" piece of wire covered with a3/4" piece
of spaghetti from Xyi-8 (52) to XVI “3 (C).
13. ( ) Fig. 3. Connect one end of a9" piece of yellow wire to XV 1-5 (SI)
and one end of a911 piece of brown wire to XV l-4 (SI). Twist the leads and
run along the chassis, as shown. Connect the other end of the yellow wire to
XV2-8 (C) and the other end of the brown wire to XV2-7 (C),
14. ()Fig 3, Cut both leads on a470KQ (yel low, violet, yel low, gold) 5%
resistor, R3, to 1". Cover each lead with a3/4" piece of spaghetti. Connect
from C11-B (C) to XVI -1 (C).
15. ()Fig. 3. Connect a4" piece of green wire from XVI-6 (5 1) to TB4-2(C).
16. ()Fig. 3. Cut both leads on a5Qmfd, 25V, electrolytic capacitor, C3,
to 11/4". Cover both leads with aApiece ofspaghetti. Connect the positive
(+) lead to XVI “3 ($2) and the negative lead (-) to TB3-1 (S4).
17. ()Fig, 3, Cu tone lead on a05 mfd (green, black, orange, black, yel low)
capacitor. Cl, to 11/4" and the other lead to 3/4". Cover the longer lead
with a1" piece of spaghetti and connect to XVI -1 (S2). Connect the other
lead to T83-3 (S3).
18. ()Fig, 3. Connect a2" piece of bare wire from Rl-3($1) toTB3-2 (S3).
19. ( ) Fig. 3. Connect a11/4" piece of bare wire FromRl-1 (SI) to J1 (SI),
20. ()Fig. 3. Cut one lead on alOKfl (brown,. black, orange, stiver) 1/2 W
resistor, R^ to 1/2" and the second lead to 1/2". Connect the longer lead
to Rl-2 (SI) and the shorter lead to XV1-9 (S 1).
21. ()Fig. 3. Connect one end of a41/2" piece of brown wire to XV2-7
(S2) and one end of a41/2" piece of yellow wire to XV2-8(S2). Twist the
leads and run along the chassis as shown. Connect the other end of the brown
wire to XV3-7 (C) and the other end of the yellow wire to XV3-2 (C).
22. (}Fig. 3. Connect one end of a 5 1/2" piece of brown wire to XV3-7
(S2) and one end of a51/2" piece of yellow wire to XV3-2 (52). Twist the
leads and run along the chassis as shown* Connect the other end of the brown
wire to XV4-7 (C) and the other end of the yellow wire to XV4-2 (C).

Fig. 3

BOTTOM OF CHASSIS ASSEMBLY
Note that the view shown in figure 2is from the top of the chassis, as if part
of the top were cut away*
1, { ) Fig. 2* On the side of the chassis, mount level control pot, Rl, as
shown* Use one 3/8 lockwasher, one 3/8 flat washers and one 3/8 hex nut*
2* (3Fig* 2. Mount input jack Jl, as shown* {Fig* 3)* Use two ^6-32
screws, two ^6 lockwashers and two ^6-32 hex nuts*
3* ()Fig* 2* Mount the Four screw terminal board, TBt, from the outside
of the chassis, as shown. Use two ^6-32 screws and two ^6-32 hex nuts. Under
one of the hex nuts, mount a^6 ground lug. Under the other hex nut, mount
the two post terminal strip, TB2 and a$6 lockwashers,
JJJ 4. ( ) Fig* 2. Mount the octal socket, J4, as shown* Note orientation.
Use two ^6-32 screws, two ^6 lockwashers and two ^6-32 hex nuts*
5* ()Fig, 2, Mount the two convenience outlets, J2 and J3,as shown* Use
two ^6-32 screws, two #6 lockwashers and two ^6-32 hex nuts on each.
6, ( ) Fig* 2* Mount the fuseholder XFI, as shown Use rubber washer out-
side of the chassis and the hex nut inside of the chassis. Do not tighten the
hex nut too much or fuseholder will crack*
7. ()Fig. 2* Mount the 3/8" rubber grommet in the remaining hole on the
rear apron.
8* ()Fig, 2A* Cut two 2" lengths of black hook-up wire* Strip 3/4" of
Insulation from both ends of each* This will leave 1/2" of insulation at the
exact center of each wire. Bend each wire into a"U IJ shape. One wall be
used as ajumper between pins 2and 3of the octal plug and the other as a
jumper between pins 6and 7of the octal plug*
9* {)Fig. 2A, Push one end of one lead into pin 2of the octal plug and
the other end of the same lead into pin 3, When the lead ends have reached
the ends of the pins, only the insulation will be visible at the rear of the plug*
10, ()Fig. 2A. Similarly connect plug pins 6and 7with the other 2" lead*
11, )Fig. 2A, Form apuddle of solder at the tip of the soldering iron. Hold
the plug with the pins down directly above the tip of the soldering iron* Dip
each of the pin-ends into which iwres have been inserted one at atime into
the solder puddle and hold there for several seconds until the solder rises up
into the pin by capillary action*
12, ( ) Fig* 2A, Press the cap down over the octal plug. It may be left off
if there is inadequate room at the desired location for mounting the chassis*

4C
TB1
TB2

TOP OF CHASSIS ASSEMBLY
1. {)Fig. 1. On the output transformer Tl, cut the red and red-yellow leads
too", the brown and brown-yellow leads to 5", the blue and blue-yel low leads
to 7", the black lead to 4", the white (slate) lead to 41/2", the green lead
to 4" and the yellow lead to 21/211 *Strip Insulation back 1/4" from the end
and tin the exposed wire with solder by dipping it into asolder pot or melting
solder onto the wire with ahot soldering iron. Mount as shown, pushing the
wires through the two large holes provided. Note that when oriented properly,
the black, white, ye llow, and green leads are easily pushed through hole "Z",
while all other leads are pushed through hole "Y11 .Use six Q~24 screws and
six ^10 flatwashers above the chassis and six ^10 lockwashers and six #10-24
hex nuts below chassis. Under one of the hex nuts, mount the cable clamp as
JsJ shown, and run all the leads from hole "Y" under this clamp (Fig. 3).
2. ()Fig. 1, On power transformer 12, cut the two red leads to 51', the
red-yellow and white leads to 2", the yellow leads to 7", the black lead to
21/2", the green leads to 31/2" and thered-black, green “black and blue leads
to 2". Tape up the end of the blue lead so that no bare wire is exposed. From
all other leads, strip the insulation back 1/4" from the end and tin the exposed
wire with solder by dipping it into asolder pot or melting solder on the wire
with ahot soldering iron* Mount as shown, pushing the wires through the two
large holes provided. The green lerds, and all other leads coming from this
same hole in the transformer are pushed through hole J, X" in the chassis, AN
*
other leads are pushed through hole "W,f .Use four ^1 0-24 screws, four ^10
flat washers above the chassis and four ^10 lockwashers and four ^1024 hex nuts
below the chassis. Mount one ^10 ground lug under each of two of the hex
nuts (Fig, 3),
3. ( ) Fig, 1. Mount the electrolytic can capacitors CIO and Cll as shown.
Note the half moon and triangle near the lugs to determine direction of mount-
ing (Fig. 3). Insert the mounting tabs into the slots in the chassis and twist
the tabs somewhat less than aquarter turn. DO NOT twist the tabs excessively
or they will shear off. Solder the tab on each without ahole, to the chassis
at its slot.
4. ()Fig, l. Mount the octal sockets XV2, XV3, XV4 and XV5, as shown,
from below the chassis. Note direction of orientation in Fig. 3. Use two ^6-32
screws, two ^6 lockwashers and two ^6-32 hex nuts* Under one of the hex nuts
of XV3, mount the one post right terminal strip, TB6.
5. ( ) Fig* 1. Mount the 9pin miniature tube socket, XVI, from the fop of
the chassis, as shown. Note direction of orientation in Fig, 3. Use two *4-40
screws, two ^4 lockwashers and two ^4-40 hex nuts.
6- ()Fig. 1, Mount the two post with ground terminal strip, TB3, three post
two right terminal strip, TB4, and two post terminal strip, TB5 as shown. Use
one ^6-32 screw, one ^6 lockwasher and one ^6-32 hex nut on each.

2C

GENERAL INSTRUCTIONS
The section oF the manual beginning with this page is the CONSTRUCTION
section. All pages in this section have page numbers followed by “C" (1C,
2C, etc.). The INSTRUCTION section resumes on the pages Following the
CONSTRUCTION section. Note that the CONSTRUCTION section is located
centrally in the book and may be removed without disrupting the INSTRUC-
TION section that both precedes it and follows it.
Care taken in the construction of this instrument will reward the constructor
with many years of satisfactory service and greater confide nee in his Instrument.
We urge you to not rush the construction, but to take all 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. Very often wires are placed
as shown for agood reason, and certainly the appearance of the completed
instrument will be improved and the difficulty of finding awiring error will be
reduced by the following the wire and parts layout shown*
UNPACKING THE KIT: Unpack the kit carefully and check each part against
the parts fist In cl u(fingThose 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 will find that the value of acomponent will vary within the allowable
circuit tolerance. For example, the 4* 7K£^ ±10% res is tor may measure any-
where between 4. 2KQ and 5. 2Kf). Tolerances on paper capacitors are sub-
stantially greater, and the tolerance for electrolytics is usually +100% and
-50%.
CONSTRUCTION HINTS: USE THE BEST GRADE OF ROSIN CORE SOLDER
ONLY, preferably one containing the new activated fluxes such a$ Kester
“Resin-Five ", Ersin “Multi core “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 acertain of a good mechanical con-
nection. 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 andshiny when
the solder has cooled. There are two extremes to be avoided; too little heat
4
and too much heat. If too little heat is supplied, 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, loose their protective coating, or break down. If you are sol-
dering close to apart, hold the lead between the part and the joint being sol-
dered 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 resistors, capacitors, and transformers
are often longer than required* These leads should be trimmed to the proper
length when necessary. Do not cut any lead until you have determined the
required length when the lead is routed as shown in the diagrams.
BASIC TOOLS REQUIRED ;These basic tools are required for the construction
of the amplifier.
1. Screwdriver -3/1
6
11 to 1/4" blade
2. Screwdriver -1/811 blade
3- Longnose pliers -5or 6,J
4. Diagonal cutters
5. Soldering Iron (100 watts), or soldergun, or pencil Iron (35 watts)
6. Gas pliers
7. High quality rosin or equivalent synthetic flux core solder. Do not use
acid or paste flux under any circumstances.
Aset of spmtites and awire stripper are also very useful supplementary tools.
PARTS IDENTIFICATION: Please note that very many of the parts for which
color coding Is given may not be color coded, but have their values and ratings
printed. The letter Kis amultiplier (X1000) and on resistors or capacitors in-
dicates that the printed numerical value must be multiplied by one thousand
to obtain the value in ohms or micro-micro farads respectively. Note also that
one microfarad (mf) is equal to one million; micro -microfarads (mmf). To aid
in rapid identification, keep in mind that 5%, 10%, and 20% resistors are
color coded whereas 1% resistor have their values printed; also that molded
tubular capacitors mayor may not be color coded, whereas disc capacitors and
electrolytics will always have their values printed. Please note the following
relationships between the units used to express resistance or capacity.
1, 000, 000 ohms (Q) -1000 kilohms (Kfi) «1megohm' (MQ)
1, 000, 000 micro-micro farads (mmf) “1micro farad (mf)
CONSTRUCTION PROCEDURE: The complete step-by-step mounting and wlr-
ing procedure follows. To keep the drawings uncrowded, unnecessary repetition
of mounting or wiring details may be omitted. Note: The abbreviation (C)
means connect but do not solder (until other leads have been connected). The
abbreviation (5) means connect and solder* The number after the ($) indicates
the number of leads at the terminal when soldering. Since all leads must be
soldered, this is acheck on wiring accuracy.
Bend the ground lug tabs on the sockets toward the chassis to prevent acciden-
tal shorting to the socket pins.

CHECKING ATYPICAL TUBE STAG*.
I. 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 wiring ana circuit components check O. K*, but
S+ voltage is high, low, or non -existent, see trouble-
shooting chart for possible causes and remedies.
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 itwill
be placed in operating condition for $7. 50 plus the cost
of parts replaced due to their being damaged in the course
of construction. NOTE: Before return ing 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.
6

Pin of Octal Plug Connected to
6~
7
1
2
4or 5*
3
*[f the preamplifier requires 350 VDC, use pin 4; If the
preamplifier requires less than 350 VDC, use pin 5and
connect adropping resistor of appropriate value and vol-
tage rating from pin 4to pin 5of the octal socket an the
HF-35chassis. Far example, if the preamplifier In ques-
tion requires 300 VDC B+voltageat IQma drain, the drop-
ping resistor will be required to drop the voltage by 50
volts (350-300 —50) at acurrent of IGma* By Ohm's Law,
the required resistance in ohms Is the voltage drop in volts
divided by the current in amperes or 50volts/* 01 amp. -
5000 ohms. The power dissipated in the resistor In watts
is equal to the voltage drop In volts multiplied by the cur-
rent in amperes or 50 volts X,01 amp =0, 5watts- For
safety aresistor of double the wattage rating should be
used* Therefore, a5000 ohm 1watt resistor is required*
Preamp. Power Lead
AC ON-OFF
AC ON-OFF
filament (6* 3VAC 1
fi lament (6* 3VAC)
B+
ground
maintenance .
CONTROL ADJUSTMENTS
The INPUT LEVEL ADJ. control is Intended to protect the
speaker system from "blasting 11 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 11 with. Start by setting the
INPUT LEVEL maximum comter-clockwise (maximum at-
tenuation), using ascrewdriver. Set the LOUDNESS con-
trol on your preamplifier to the maximum clockwise 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 rotate the INPUT LEVEL
ADJ. control clockwise until the music Is at normal (or
concert) listening level* This completes the adjustment,
which need not be repeated.
TROUBLE-SHOOTING PROCEDURES
Your amplifier should require little service except for nor-
mal tube replacement* We recommend no substitutions
for the tube types used In this amplifier. The EF86, EL34,
and GZ34 types are distributed nationally by fheAmperex
Electronic Corporation {230 DuffyAve*, Hicksvi Ile, L* I.
,
N.Y.) and Mu Hard Ltd. (Interna tional Electronics Corp*,
Q] Spring St., N.Y. 12, N.Y*) If necessary, replace-
ments can be obtained directly from EICO.
It should be noted that slight red coloring of the EL 34 out-
put tube plates In operation is not abnormal and does not
Indicate that the amplifier is operating improperly*
The HF-35 is intended for operation at aline voltage of
117 volt AC, Component failure Is likely at aline vol-
tage above 124 volts AC, If the line voltage at your
location is higher than 120 volts, use the special tap that
is provided on the power transformer. Disconnect the
black-red wire from the fusehotder. In its place, connect
the black-green wire to the fuseholder* Tape up the black-
red wire to prevent It from shorting- This provides safe
operation up to line voltage of 132 volts- If your line
voltage is above this, use a voltage adjusting device or vol-
tage regulator of adequate volt-ampere capacity (200VA).
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 35watts output as
well as the corresponding Ike signal voltages.
To isolate the source of unusual hum or noise In your
system, first turn off the AC power and then unplug the
audio cable connecting to the amplifier input. Then turn
the AC power on again and note whether humor noise has
decreased. If It has, the fault is in the preampi ifier or
associated equipment and measures should be taken to cor-
rect It as described In the service notes for these units.
|f It Is desiredto provide agood building ground For your
entire system, run a lead from under speaker connection
terminal "G" to acold water pipe* Do not connect such
qground 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, Turn the
INPUT LEVEL ADJ. control maximum clockwise (no atten-
uation) and set the Input signal to 0*43 .alts, ihe cor-
responding grid and plate signal voltages for this Input are
indicated on the schematic diagram. This procedure should
suffice to localize the defective stage.
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 are-
sistance and voltage check of the stage, using the data in
the Resistance and Voltage chart. Disconnect the ampli-
fier from the power line and discharge capacitors prior to
making any resistance check and prior to removing either
or both of the EL34 output tubes*
5