Electro-Voice E-V 1144A User manual

ELECTRONICS SERVICE MANUAL
E-V 1144A SOLID STATE AMPLIFIER
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ELECTRO-VOICE INC., BUCHANAN, MICHIGAN 4S1Q7

INDEX
I. INTRODUCTION
A. Specifications &Description
B. Features
C. Control Functions
D. Preparing for Operation
II. DISASSEMBLY
III. REPLACING LAMPS &FUSES
IV. TROUBLE SHOOTING CHART

INTRODUCTION
This service manual was designed with the technician in
mind. It has been kept as brief as possible without over-
simplification. AH procedures are presented in adear step-
by-step manner. Although we have tried to anticipate all of
your problems and questions, in special instances you
may need additional guidance. Address any such inquiries
to our Technical Service Department
DESCRIPTION
Representing an entirely new and unique approach to the
design of stereo high fidelity components, the Electro-
Voice E-V 1144A stereo control amplifier incorporates
the latest "state of the art" transistor circuitry in an ex-
quisitely styled, remarkably small package. Despite its
small size, the E-V 1144A delivers 65 watts IMF music
power with low distortion.
In addition to superb styling and performance, the
E-V 1144A amplifier offers' many operating conveniences.
Acolor-coded volume control allows simple op>eration,
even by those unfamiliar with component stereo. Colorful
indicator lights show at aglance the program source
selected. The front panel stereo headphone jack is live at all
times, v^ile aspeaker mute switch allows the speakers to
be disabled at will without affecting headphone operation.
FIGURE 1
The sheets are punched to fit athree-ring binder so that
any production changes and additional service tips can be
easily added. This will keep your Electro-Voice Service
Data as up-to-date as possible.
SPECIFICATIONS
POWER OUTPUT
IMF Music Power: 65 watts into 4ohms
50 watts into 8ohms
Continuous Sine Wave: 18 watts per channel
FREQUENCY RESPONSE: +1 .5 db.20-20,000 Ha at rated
output
tl.5 db, 20-30,000 Hz at 1watt
HARMONIC DISTORTION: Less than 1.0%at rated output
HUM and NOISE
High Level Inputs: Better than 70 db below rated output
Magnetic Phono Input: Better than 60 db below rated output
CHANNEL SEPARATION; 40 db minimum at 1,000 Hz
INPUTS: Mag Phono—Turter—Aux—Tape
(high level)
INPUT SENSITIVITY
Phono: 3mv
Tuner,Aux,Tape: 150 mv
CONTROLS (ROTARY)
Bass; -flOdb,—12 db at 50 Hz
Treble: +10db,-12 db at 10,000 Hz
Selector: Phono—Tuner—Aux
Balance:
Volume: With On/Off Switch
CONTROLS (SWITCHES)
Mode: Stereo/Mono
Tape Monitor: Source/Tape
Loudness: On/Off
Speaker: On/Mute
OUTPUTS
Speakers: 4—16 ohms per channel
Stereo Tape Recorder
Stereo Headphones; On front panel
OUTPUT DAMPING FACTOR: one switched
one unswitched
POWER REQUIREMENTS; 110-120 volts
50—60 cycle AC
01 MENSI ONS: 3-3/8" high,8-3/8" wide, 10-1/4" deeo
Page 1

FEATURES
LOUDNESS CONTROL: Compensates for decreased ef-
ficiency of the human ear to low frequencies at low
listening levels. Only in effect below 12 o'clock position
of volume control.
SPEAKER MUTING SWITCH: Disables speakers for head-
phone listening. Output is available at the headphone
jack regardless of muting switch position.
COLORED INDICATOR LIGHTS: Show the input source
selected—phono, tuner, auxiliary.
CONTROL FUNCTIONS
TAPE/SOURCE: Selects either tape (high level) or Inputs
controlled by selector switch. Allows you to monitor
what has actually been recorded on tape.
STEREO/MONO: Allows either two-channel amplifica-
tion of stereo signal source or combines input signals for
monophonic reproduction through both speakers. Mono-
phonic input plays back through both speakers with
switch in mono position.
SPEAKER MUTE; Permits either simultaneous head-
phone and loudspeaker or headphone listening only.
LOUDNESS: Causes volume control to automatically
boost bass at low setting which compensates for hearing
deficiencies at low levels.
SELECTOR; Allows choice of signal source—phono, tuner,
or other high level source (auxiliary).
BASS; Approximately 12 db boost and 16 db cut at 50
Hz (both channels) to compensate for speaker system
characteristics and listening preference.
TREBLE: Approximately 12 db boost and 16 db cut at
10,000 Hz, both channels.
BALANCE: Allows choice of left or right speaker opera-
tion and provides method of compensating for other
system imbalances.
VOLUME-OFF/ON: Controls listening level and, when
used in conjunction with loudness control, maintains
natural sound balance even at low volume levies.
PREPARING FOR OPERATION
1.
Be sure power switch (on volume control) is "off"
before plugging amplifier into wall outlet supplying
115-120 volts AC.
2. Connect left and right channel speakers at ter-
minal block using diagram printed on bottom of
amplifier. NOTE: AVOID SHORTING SPEAKER
TERMINALS TO KEEP FROM BLOWING OUT-
PUT FUSES.
3. Connect outputs from tape recorder, turntable or
changer and tuner to corresponding input jacks.
4. Set tape/source switch to source position and turn
selector to appropriate input Note: if tape player
is used, put tape/source in tape position.
5. Turn unit or b/ advancing volume control until a
click is heard. Advance control to acomfortable
level and set tone controls at approximately 12:00.
6. Set balance control for equal output from both
speakers.
7. Check speaker phasing by reversing leads to one
speaker while standing mid-way between and in
front of the speakers. The stereo/mono switch
should be in the mono position for this check. Make
final speaker connection with the polarity that de-
livers fullest bass and causes the sound to appear to
come from the area between the speakers.
Page 3

DISASSEMBLY
REMOVING BLACK METAL COVER
1.
Remove phillips head screws in rear of cabinet.
(See Figure 2below)
FIGURE 2
2.
Slide cover back and remove.
REMOVING WALNUT END PANELS
3. Remove phillips screw from each panel.
(See Figure 2above)
4. Remove brass grounding strap.
5. Pull back firmly on panel to disengage metal clip.
REMOVING FRONT PANEL
6. Remove the control knobs by pulling forward.
7. Remove felt washers behind knobs.
8. Remove 2nuts from threaded studs on front panel.
(See Figure 3below)
FIGURE 3
9.
Remove the front panel.

REPLACING LAMPS AND FUSES
REPLACING FUNCTION INDICATOR LAMPS
1. Follow Steps 1thru 9under disassembly.
2. Loosen silk tape holding fishpaper shield in place.
3. Bend shield back to gain access to bulbs. (See Fig. 4)
4. Replace defective lamp(s) and reverse steps above.
FIGURE 4
REPLACING OUTPUT FUSES IF2 &F3)
1. Follow Step 1and 2under disassembly.
2. Pry defective fuse from holder.
3. Replace with 1.5a SLO-BLO fuse and reassemble
amplifier.
REPLACING POWER FUSE IFII
1. Follow Steps 1and 2under disassembly.
2. Pry defective fuse from holder.
3. Replace with a1.5a SLO-BLO fuse and reassemble
amplifier.

PARTS IDENTIFICATION
TRANSISTORS MISCELLANEOUS
43054 Lo- Noise 17139 Phone Jack
43044 SE-6002 17137 Phono Jack (dual)
43045 SE-4002 20797 Strain Relief
43046 B10167 27258 Speaker terminal strip
76660-BX Side Panel Clip
16412 Power Cord
COMPONENTS 20893 Heat Sinks
20747 Mica Insulator
77117 Fishpaper Lamp Board
42407 2500 @25 wv capacitor 77118 Ground Strap
43067 750 @100 piv diode 43055 Bulb
15200 Driver transformer 38294 Felt Washer
15174 Power transformer A85081-ED1Front Panel
A76484 Side Panel
SWITCHES &CONTROLS A76489-JD Top Cover
A764gg-RA Lens
46415 Balance (25k)
46412 Volume (25k) KNOBS
46413 Bass/Treble (100k)
56084 Selector switch
56075 Rocker switch 76558-CX Volume On/Off
76557-CX Bass/Treble/BalarKe
7671 7-CX Selector Switch
PRINTED BOARDS
84949 PC-1 Preamp corr>plete
84950 PC-2 Driver/Powfer Amp complete
84950 PC-3 Drh/er/Power Amp complete
84951 PC-4 Power Supply complete
77116 Power Supply (board only)