Akai PR-A04 User manual

STEREO PRE-AMPLIFIER
MODEL PR-AOQ4
DC STEREO POWER AMPLIFIER
move. PA=-WO4

PR-AO4
TABLE OF CONTENTS
SECTION 1 MODEL PR-A04 ........... 00.0 eee eee 3
SECTION 2 MODEL PA-W04 ............ 0.0 eee eee 17
SECTION «3° PARTS UIST isis jdiead Seana Sa tiied a eens 33
SECTION 4 SCHEMATIC DIAGRAM ................ 54

IL
SS 25
VIL.
SECTION 1
STEREO PRE-AMPLIFIER
MODEL PR-A04:
ALSO APPLICABLE TO BLACK PANEL MODEL
TABLE OF CONTENTS
TECHNICAL
DATA...
2...
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ee
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teens
4
DISMANTLING
OF
UNIT.
2.0...
ee
ee
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eee
5
CONTROES
©
isso
55
565
8
6S
pice
Seeing
BE
we
ea
a
ig
Ee
aa
ee
Sle
ee
go
6
PRINCIPAL
PARTS
LOCATION
........
0.
ce eee
eee
eee
eens
7
VOLTAGE
CONVERSION
..
1...
2...
ccc
ee
ee
ee
ene
8
ADJUSTMENT
..
1...
0...
e
ce
ee
eee
ere
ee
eet
eens
9
CLASSIFICATION
OF
VARIOUS
P.C
BOARDS
..........-..-.+--:
10
1.
P.C
BOARD
TITLES
AND
IDENTIFICATION
NUMBERS...........-
10
2.
COMPOSITION
OF
VARIOUS
P.C
BOARDS
..........--.---.---
.
ll

I. TECHNICAL DATA
INPUT SENSITIVITY/IMPEDANCE/
SIGNAL TO NOISE RATIO (IHF “A”)
PHONO 1/2 (MM)
PHONO 1 (MC)
3 mV/47 kohms/82 dB
0.08 mV/10 ohms/75 dB
TUNER 150 mV/47 kohms/102 dB
AUX 150 mV/47 kohms/102 dB
TAPE PLAY 1 PIN: 150 mV/47 kohms/102 dB
DIN: 150 mV/100 kohms/80 dB
TAPE PLAY 2 PIN: 150 mV/47 kohms/102 dB
OUTPUT LEVEL/IMPEDANCE
TAPE REC 1 PIN: 150 mV/600 ohms
DIN: 30 mV/30 kohms
TAPE REC 2 PIN: 150 mV/600 ohms
OUTPUT 1 V/600 ohms
RATED LOAD IMPEDANCE
47 kohms
PHONO MAX. INPUT LEVEL (1 kHz)
PHONO 1/2 (MM)
PHONO 1 (MC)
400 mV
10 mV
FREQUENCY RESPONSE
TUNER/AUX/TAPE PLAY 1, 2
PHONO 1/2 (MM) (RIAA curve deviation)
PHONO 1 (MC) (RIAA curve deviation)
TOTAL HARMONIC DISTORTION
(20 Hz to 20 kHz)
TUNER/AUX/TAPE PLAY 1, 2
PHONO 1/2 (MM)
PHONO 1 (MC)
5 Hz to 100 kHz + 0.5 dB
30 Hz to 15 kHz + 0.2 dB
30 Hz to 15 kHz + 0.2 dB
0.005% at output 10 V
0.005% at output 10 V
0.005% at output 10 V
(Volume control set at Max. position)
TONE CONTROL
BASS
TREBLE
SUBSONIC FILTER
HIGH FILTER
CHANNEL SEPARATION (AUX)
+8 dB at 100 Hz
+8 dB at 10 kHz
12 dB/oct. at 18 Hz
12 dB/oct. at 10 kHz
70 dB (Shorted Circuit)
MISCELLANEOUS
SEMICONDUCTORS
je
Transistors: 16, Diodes: 15, FETs: 2, ICs: 6
POWER REQUIREMENTS
120 V, 60 Hz for U.S.A. and Canada Models
220 V, 50 Hz for Europe except UK Models
240 V, 50 Hz for UK and Australia Models
110/120/220/240 V, 50/60 Hz internally Switchable
for other countries Models
POWER CONSUMPTION
DIMENSIONS (W x H x D)
WEIGHT
15 W
440 x 78 x 313 mm (17.3 x 3.1 x 12.3 inches)
6.1 kg (13.4 Ibs)
* For improvement purposes, specifications and design are subject to change without notice.

i. DISMANTLING OF UNIT
In case of trouble, etc. necessitating dismantling, please dismantle in the order shown in the photographs. Reassemble
in reverse order.
SCREWS
SCREWS
FRONT PANEL SCREWS
SCREWS
UPPER COVER

ON OAAN >
11.
12.
13.
14,
15.
CONTROLS
POWER SWITCH
BASS CONTROL
FILTER SWITCHES
MODE SELECTOR
LOUDNESS SWITCH
VOLUME CONTROL
dB VOLUME SCALE
INPUT SELECTOR INDICATOR
INPUT SELECTOR
PHONO SELECTOR
REC (Recording) SELECTOR
STEREO BALANCE CONTROL
CAPACITANCE CONTROL
GROUND TERMINALS
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
. AC OUTLETS
ms NUMBER UNSWITCHED SWITCHED BAD
41265-55150 iu
ARASH COS MADR AAR
SHOCK BAZARD 1 OPER!
aiSaHE OE cuss iS ERLEVER !
fe ree
DERUEREMGSELFANR -MICKT SFFAER / TOTAL TOOW MAK? % ,
200WMAX |.
SAITIIIE tn case of use outside of indicated AC 110-2409
power source ares, consult our sarvice
shop for necessary convermon. §0/60Hz 15W
Fig. 1 Controls
TUNER TERMINALS
AUX TERMINALS.
TAPE 1 SYSTEM REC/PLAY TERMINALS
TAPE 1 SYSTEM DIN JACK
(Some models do not have this facility)
TAPE 2 SYSTEM REC/PLAY TERMINALS
OUTPUT TERMINALS
AC OUTLETS (Some models do not have this facility)
AC CORD (Some models are equipped with an AC Inlet
instead of an AC cord. Connect with an appropriate
power cord.) :
PHONO 2 INPUT JACKS
PHONO 1 INPUT JACKS
|
|
|
;

iV. PRINCIPAL PARTS LOCATION
ae
ce
Be
A
FILTER
REC
SELECTOR
SWITCHES
:
SWITCH
SW
4
HIGH
BASS
sw4
LOUDNESS
VOLUME
LED
P.C
BOARD
CONTROL
SUBSONIC
CONTROL
CONTROL
PRA-4002B
VR2
sw3
swe
vRI
INPUT
TREBLE
MODE
BAL
ANCE
SELECTOR
CONTROL
SWITCH
CONTROL
SWITCH
VRI
Swi VRt
SW3
PHONO
SELECTOR
SWITCH
swi
Fig. 2 Front View
POWER
POWER
PRE
AMP.
CAPACITANCE
SWITCH
TRANSFORMER
P.C
BOARD
CONTROL
SWITCH
Swgol
T901
PRA-4001A
swe
FUSE P.C BOARD
PRA-4003 (U/T)
.
-
TONE CONTROL VOLUME
P.C BOARD P.C BOARD
PRA-4002A PRA-4001C
Fig. 3 Top View

V. VOLTAGE CONVERSION
SCREW
Seem Ceemrarere |
IS sr ATES SER CE LC RNS aa
FUSE
PC
BOARD
(PRA-
4003)
=
POWER SWITCH
ry i
POWER TRANS,
Fig. 4 Voltage Conversion (U/T Model)
1. U/T Model (Refer to Fig. 4)
1) Switch OFF the power supply and remove the
plug from the mains supply.
2) Loosen holding screws and remove the top panel.
3) Remove the screw holding the Fuse P.C Board
located near the power transformer.
4) Remove existing Line Voltage Fuse and insert
required Line Voltage Fuse in the proper fuse
holder.
110V : 800mA 250V
220V : 400mA 250V
240 V : 400 mA 250V
’ 2. Models other than U/T
No voltage conversion.

VIL ADJUSTMENT
REAR PANEL
sw4
sw3
Sswi-2
icp
SWwI-1
=
Ta
aun
Center
Center
Off-set
Off-set
Voltage +0 pe Voltage
(O00
nooo
@ | @
IK ohm IK ohm
ml Fl rel wae?
O1O Ono
FRONT PANEL
DC Voltmeter
Lee eee
Fig.
5
Pre
Amp
P.C
Board
PRA-4001A
CENTER OFF-SET VOLTAGE ADJUSTMENT
(Refer to Fig. 5)
Connect the Digital Voltmeter or DC Voltmeter between
the test point on the Pre Amp PC _ Board
PRA-4001A and the ground.
Adjust the VR 1 (1 kohm) so that Voltmeter reading is
0+0.5V.
|
|

VIL CLASSIFICATION OF VARIOUS P.C BOARDS
1. P.C BOARD TITLES AND IDENTIFICATION NUMBERS
P.C Board Number
P.C Board Title
PRA-4001A j
Pre Amp P.C Board
Switch P.C Board PRA-4001B
Volume P.C Board PRA-4001C
Tone Control P.C Board PRA-4002A
PRA-4002B
PRA-4003
PRA-4004
PRA-4005
PRA-4042
Chart-l
10

2. COMPOSITION OF VARIOUS P.C BOARDS
1) PRE AMP P.C BOARD PRA-4001A
fe PHONO 1
47KO
33KQ. 7'O0KQ.
‘N
PHONO 2— —MGC
m oe) wD
2SC2240
2SA970
2SC536K-NP
2SB63 1K
2SD600
CAPACITANCE | (pF)
390
200 7-N 500
100
1c 178 15
R3@b 10Q(F) pal
Wa
oO“ -O
ral
a
TAPE
R1Ob 820
DUBBING
©)
¢ ©) RIGHT
SW 4
(REC SELECTOR] SELECTOR)
OFF
PHONO 1 TUNER
/
Pn Bo = AUX
2—_|—
LerT vé
LEFT
[REC]
©)
RIGHT
J5
RIGHT
PRA-4001C
Ih
's PRA-4002A
i4
1
ft ale
eons os it by
20-;——___Lo 3
d f |, PRA- 4003
i)
W
J
Ld Le
c
rey rf.
tto-+————+0 !|3
'ao4 lo 2 PRA-4002A
'30-+——_—_—_—__+0 1
tJ t-4
11

3) SWITCH P.C BOARD PRA-4001B
2) TONE CONTROL P.C BOARD PRA-4002A
PRA- 4002B
oor
vu
|
zor val
1 EV EV
COb—vEd
1oO
g
bes
ze
PRA-4001A
t
L
r7
"
vi00v-Vud
2
INPUT
SELECTOR
4) VOLUME P.C BOARD PRA-4001C
PRA —- 4042
PRA-4002A
PRA-4002A
4001A PRA~
41a
AUD
VOLUME
ae
aay
Aud
iS ee
a
|
TaA AYS
Au
Aus
TREBLE)
12

5) BALANCE P.C BOARD PRA-4042
GRN GRY GRY GRN
PRA- 4002A
Eiosst ani natvs sok sa ues a nob suemreette striae ek oe
BALANCE
6) LED P.C BOARD PRA-4002B
PRA — 4001B
1234 5 6
4
I 2
13°

7) FUSE P.C BOARD PRA-4003 (2ED) (U/T)
aN
A04T-70
PR-
proeneees
PRA- 4001A
2
2
5
{ao0g/i0%0
19
-
#
BP
(a)
006/10°0
29.0%
yi
—*
006/2b0'0
INDSOI IND902
on
BRN IOV
AC
OUTLETS
aA
C901 O.01/125V
Fl 80mA 250V (110V)
F2 400mA 250V (220V)
F3 400mA 250V (240V)
8) FUSE P.C BOARD PRA-4004 (2ED) (CSA, AAL)
wa
eictemnntenomeenne
8
ON
00¢/200°0
£5
——t—_—*
j,
t,006/10'0 29
(d)
00s/10°0
19
,
b=.
Asz!
wwose
v4
7
4 Bs § <t =
on oO
12
4
IND902 IND9OI
18
1; LHM we
+
LHM
oe alone
“4
'
4
sy
Ji
ral
PRA-40014
bL----
AC OUTLET
+ _

LL
9) FUSE P.C BOARD PRA-4005 (2ED) (CEE, UK, SAA)
-, Mgzumneeeen naar enenemmneren eee!
€3 0.047/4Q0(K)
soor-vag @
BSS
~
ivi
a5
8
4
AC
220v.
AC
240V
PRA~4001A
5OHz
SOHz
a
AC
INLET
A TOI
PR-AO4T- 40 (CEE)
PR-AO4T-5O (UK)
WARNING: AINDICATES SAFETY CRITICAL COMPONENTS. FOR CONTINUED SAFETY,
REPLACE SAFETY CRITICAL COMPONENTS ONLY WITH MANUFACTURER'S
RECOMMENDED PARTS 7 :
AVERTISSEMENT: AIL INDIQU LES COMPOSANTS CRITIQUES DE SURETE. POUR
MAINTENIR LE DEGRE DE SECURITE DE L' APPAREIL NE REMPLACER LES
CONPOSANTS DONT LE FONCTIONNEMENT EST CRITIQUE POUR LA SECURITE
QUE PAR DES PIECES RECOMMANDEES PAR LE FABRICANT
15

MEMO

Lo
$< 28
SECTION 2
DC
STEREO
POWER
AMPLIFIER
ove.
PA-
WO4
ALSO APPLICABLE TO BLACK PANEL MODEL
TABLE OF CONTENTS
TECHNICAL
DATA...
1...
ee
ete
teens
18
DISMANTLING
OF
UNIT...
2...
ee
ee
eee
19
CONTROLS
.....
2...
ccc
ce
eee
eee
eee
etter
e
ene
20
PRINCIPAL
PARTS
LOCATION
..........
200
ee
eee
eee
cert
eeees
21
VOLTAGE
CONVERSION
..........
2c
eee
eee
eee
eee
ee
eens
22
ADJUSTMENT
........
2.
cece
eee
eee
eee
terre
ee
tenets
23
.
CLASSIFICATION
OF
VARIOUS
P.C
BOARDS
.........---0
2
eee
24
1.
P.C
BOARD
TITLES
AND
IDENTIFICATION
NUMBERS
..........-
24
2.
COMPOSITION
OF
VARIOUS
P.C
BOARDS
..........----
500055
25
17

I. TECHNICAL DATA
RATED
POWER
OUTPUT
48
watts
per
channel.
minimum
RMS.
at
8
ohms
from
20
to
20,000
Hz
with
no
more
than
0.008%
total
harmonic
distortion.
TOTAL HARMONIC DISTORTION 0.008% at rated power output
INTERMODULATION DISTORTION 0.008% at rated power output
SIGNAL TO NOISE RATIO (IHF “‘A”’) 115 dB
RESIDUAL NOISE (IHF ‘‘A’’) | Less than 0.05 mV at 8 ohms
POWER BANDWIDTH (IHF) | 6 Hz to 60 kHz at 8 ohms
(Total Harmonic Distortion 0.05%)
DUMPING FACTOR (IHF) More than 100 (1 kHz, 8 ohms)
FREQUENCY RESPONSE DC to 100 kHz +0 dB, —-0.5 dB
INPUT SENSITIVITY/IMPEDANCE 1 V/47 kohms
OUTPUT
SPEAKERS A, B (4 to 16 ohms)/A+B (8 to 16 ohms)
HEADPHONE 8 to 16 ohms
SUBSONIC FILTER 12 dB/oct. at 5 Hz
MISCELLANEOUS
SEMICONDUCTORS Transistors 27, Diodes 47, FETs 2. ICs 7
POWER REQUIREMENTS 120 V, 60 Hz for U.S.A. and Canada Models
220 V, 50 Hz for Europe except UK Models
240 V, 50 Hz for UK and Australia Models
110/120/220/240V, 50/60 Hz internally Switchable for
other countries Models
POWER CONSUMPTION 300 W
DIMENSIONS (W x H x D) 440 x 78 x 373 mm (17.3 x 3.1 x 14.7 inches)
WEIGHT 6.7 kg (14.7 lbs)
* For improvement purposes, specifications and design are subject to change without notice.

I. DISMANTLING OF UNIT
Inc: of trouble, etc. necessitating dismantling, please dismantle in the order shown in the photographs. Reassemble
in reverse order.
SCREWS
SCREWS
FRONT PANEL
SCREWS
SCREWS
UPPER COVER
SCREWS
19

20
CONTROLS
aa BEMAL NUMBER
sa ao a wu
: ACANELIIN COLD ADE
AKA! ELECTRIC CO,, LID.
mone. No RPA-WOG
* MADE IN JAPAN
SPEAKER A.B (4-162), A+B (8-160)
an OFT
SHOCK MAZARG- BE NET OPENS
MSOBE BE Cue ~ WE PAS BMEVER !
CAUTION: 10 case of use outside o
SERVQUUMESGEFANR- WICKT DRFWER / power source er@z, consult our
eses reo PON on swn op
= N
Shap for necessary conversion
Fig. 1 Controls
POWER SWITCH
HEADPHONE JACK
SPEAKER SYSTEM SELECTOR SWITCHES
METER SWITCH
FLD BAR METER
CLIPPING INDICATOR
DC OPERATION INDICATOR
DC/LOW CUT OPERATION SWITCH
INPUT JACKS
SPEAKER OUTPUT JACKS FOR A, B SPEAKER SYSTEMS
EXTRA AC OUTLETS (Some models are not equipped with
this facility)
AC CORD (Some models are equipped with an AC Inlet
instead of an AC cord. Connect with an appropriate power cord.)