Sansui AU 111 Service Manual

Page 2

EGRIENTS

FEATURES ...............................................
SPECIFICATIONS/CHARACTERISTICS.................;....
CONNECTIONS ......... ' ...........................................
SWITCHES AND CONTROLS ..................................
OPERATIONS ......................................................
HOW TO KEEP YOUR AU 111 IN TOP CONDITION.

SERVICE NOTE ..................................................
SCHEMATIC DIAGRAM ........................................
PARTS LIST ......................................................
PARTS LAYOUT ................................................

3, 4

5, 6

7, 8, 9, 10 V
11, 12, 13, 14
15, 16

17, 18, 19,
20, 21

22

23, 24, 25

26

Page 4

The Model AU-lll is equipped with a super wide
band type output transformer with large capacity
and a power transformer with excellent regulation
ability to obtain high power without any power
loss and distortion.

THREE-DIMENSIONAL PER-

FORMANCE POSSIBLE WITH
CENTER-CHANNEL OUTPUT

TERMINALS

The Model AU-lll has
output terminals for the
center channel amplifier.
Connect them to a monaural
amplifier to produce a three
dimensional effect.

SILICON -TRAN SISTORIZED *
HEAD AMPLIFIER

The head amplifier employs new silicon transistors
to eliminate hum and noise completely. With
this, a low-output MC pickup cartridge and a tape
deck can be used.

CATHODE FOLLOWER CIRCUIT
IDEAL FOR FIRST STAGE OF
INTERMEDIATE AMPLIFIER

For better performance the first stage of the inter-
mediate amplifier employs the cathode follower
circuit in which the input impedance is higher
and the output one is lower. The TAPE REC
terminal is connected to this circuit so that there
occurs no trouble that was caused by too low
input impedance of the tape recorder.

4-OUTPUT AND 7-IN PUT
CIRCUITS

The Model AU-lll can be used for almost all
purposes by means of 4 output and 7 input circuits:
PRE AMP, TAPE REC, CENTER CHANNEL
(x2) PHONO (x2), TAPE TERMINAL etc.

COMPLETE RANGE OF
ACCESSORY CIRCUITS

The Model AU-lll has the complete range of
accessory circuits: tape equalizer, CR feedback type
low and high filters, loudness control tape monitor
tape recording output terminal (cathode follower)
presence control, center channel output terminals,
phasing switch sub volume, headphone jack etc.

BEST DESIGN FOR STEREO
ENTHUSIASTS

The Model AU-lll is designed especially for ease
of operation and beauty of appearance. Black-
rnatted finishing of the front panel plus gold-plated
knobs will enhance the beauty of your room.

Page 12

TONE SELECTOR, TREBLE (7)

The TONE SELECTOR, TREBLE can
change the frequency range of high-notes
covered by the TREBLE tone controls:

DEFEAT: The treble tone control circuit
is turned off and the completely flat fre-
quency response characteristic is obtained
in the high notes alone.

5 KCpS: The upper or lower limit of the
frequency range of the TREBLE tone
controls is changed to 5000 cpsi

2.5 chs: The upper or lower limit of

the frequency range of the TREBLE
tone controls is changed to 2,500 cps.

LOW FILTER (8)

To eliminate buzz hum and other noises
at the low frequencies set the LOW
FILTER switch on.

HIGH FILTER (9)

To eliminate the surface noise in a disk
radio noise caused by a fluorescent lamp
and other noises at the high frequencies.
set the HIGH FILTER switch on.

j ronz SELECTOR

or; or:

Low r~ FtLT-HIGH

CENTER CHANNEL VOLUME
CONTROL (10)

The CENTER CHANNEL volume control
is used to adjust the output level at the
center channel terminal located at the back
of the unit. Turn it clockwise and the
volume is increased; turn it counterclockwise
and the volume is decreased. For the 3-
channel stereo adjust it to the same output
(volume) as the unit depending on the
input level of the additional main amplifier
connected to the center channel terminal.

CAUTION :

The CENTER CHANNEL volume control must

be in no control position unless the unit is used
for 3-channel stereo.

BALANCE CONTROL (11)

Proper balance for a stereo exsists when
the sound seems to originate at a point
midway between the right and left speaker
system. If one speaker system is louder
than the other, the adjusting of balance is
necessary

HEADPHONE JACK (12)

To use a headphone set, plug in the HEAD-
PHONE jack. Although any type of head-
phone is usable for the unit (if its plug fits
well in the jack), a dynamic stereo head-
phone is recommended for use.

Page 20

SEREEEE iiDTE

Symptom Probable Cause What to Do
, l
No power when power switch is 1 Defective power switch Replace.
5th on 2. Defective line cord Replace.
3. Loose contact between plug and socket or _ Recondition or replace.
defective plug
4. Blown fuse 5 Replace.
i If again blown after replacing, check power
;transformer (T3) & path condenser (C30) in
, power circuit for short-circuit.
Power indicator is lit when power
switch is pushed on, but;
A) the unit does not work at all. 1. Defective tube Check V)_Vfl and silicon diodes.
2. Abnormal voltage in tubes and other Check voltage in tube and other parts and
parts replace, if necessary. If voltage is OK, check
AUX input circuit and hereafter.
B) PHONO and TAPE does not 1. Defective head amplifier (transistor section) Replace transistor head amplifier unit.
function.
2. Defective head amplifier (tube section) Replace Vi. and/or Vm.
3. Defective selector switch Replace or repair S, and/or 8,1,.
4. Loose contact or short-circuit between input Replace or repair.
terminal and pin jack
5. Defective record player, tape recorder, or Replace.
others, connected to the unit
6. Defective coupling condenser Replace Ca and/or Cg.
C) Weaki sound on AUX, PHONO 1. Abnormal voltage in power circuit and Check and repair.
and TAPE other parts
A) Normal voltage at every part 1. Defective fixed resistance Check R45, R, R43, R, R5; and R. I
but weak sound on AUX
2. Short-circuit in output transformer Check T, and T2.
3. Discharged capacitor Check C. C, C, C2, C39, Cw, C43, 055,
C55: C57. an» Cm. C71 and C72; tubular electro-
lytic capacitor C35, Cafi, C, C55. 059 and C.
4 Aged tube Check V2~V12r
5r Half-fixed resistance not properly adjusted Check and adjust VR, and VRz.
B) Normal voltage at every part 1. Defective selector switch Replace or repair 51, and/or 5,1,.
but weak mum on PHONO 2, Abnormal input circuit: loose contact Replace or repair.
and TAPE between input terminal and pin jack;
defective shield wire
3. Defective record player, tape recorder or Replace
others, connected to the unit
4 Defective coupling condenser Check 0,, C2, Cr, C5 Ca and Cgr
5. Discharged bypass condenser Check C5 and C7.

H20-

Page 21

SERlilCE ELITE

Symptom Probable Cause What to Do
A) Distorted sound on AUX 1. Aged tube Check V2~V,2.
2. Short-circuit in output transformer Check and repair Ti and T3.
3. Defective loundspeaker Replace.
4. Defective record player, adaptor or others, Replace.
connected to the unit
B) Distorted sound on PHONO & 1. Defective record player, tape recorder or Replace.
TAPE others, connected to the unit
2. Defective tubular electrolytic capacitor Replace C1 and/or Ca.
3, Disconnection at fixed resistance Check R3, R,, R, R. R, R, R". R15, R",
R20: R21 and R22-
A) Hum on AUX 1. Electrolytic capacitor discharged Check C13. 074. 075. C75. CBS and C55.
2. Defective tube . Check V2~V,g.
3. Defective record player, adaptor or others. Replace.
connected to the unit
4. Hum balancer not properly adjusted Check VR and VRla.
5, Disconnected NF resistor Check R13 and R1,.
B) Hum on PHONO and TAPE 1. Defective shield wire and/or wrong con- Replace and connect correctly.
nection of record player, tape recorder or
others
2. Audio system and shield wire induced Keep proper distance between audio system
from outside and inductor.
3. Residual hum of audio system connected Replace or repair.
to the unit
A) Noise on AUX and TUNER 1. Fixed resistor badly connected or touched Check R23, R2, R34, R35, RQ, R49, R5, R,
by another part R15. R13. Rea. R54: R55 and Res-
2. Capacitor nearly short-circuited or touched Check 1 and 2.
by another part
3. Primary coil of output transformer nearly Check T, and T2
disconnected
4. Defective tube Check V2~V12.
B) Noise on PHONO and TAPE 1. FixedCl resistor defective or nearly discone Check R,~R25.
necte
2, Defective capacitor Check C1~Cg and C4~Cg.
3. Noise or bed connection of audio system Replace or repair.

connected to the unit

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