NAD 3020B User manual

SERVICE
MANUAL

BS aes i os
CONTENTS
3020B AND 3120 REAR PANEL CONNECTIONS
SPECIFICATION
INSIDE VIEW & BLOCK DIAGRAM
ALIGNMENT
3020B PCB PARTS LOCATION AND WIRING DIAGRAM
3020B SCHEMATIC DIAGRAM
3120 PCB PARTS LOCATION AND WIRING DIAGRAM
3120 SCHEMATIC DIAGRAM
3020B EXPLODED VIEW
3020B PARTS LIST
3120 PARTS LIST
PACKING DIAGRAM
3120 EXPLODED VIEW
PAGE
PAGE
PAGE
PAGE
PAGE
_ PAGE
PAGE
PAGE
PAGE
PAGE
PAGE
PAGE
PAGE
ao oO WwW
9-10
11-12
13-14
15-16
17-18
19-22
23-29
30
31-32

3020B
AND
3120
REAR
PANEL
CONNECTIONS
ENGLISH
Ground
Phono
MM/MC Phono Selector
Tuner
Aux
. Tape Play/Record
PR a eN
GROUND
1 3
'. Pre-Amp Out. Normal in, Lab In
. Speakers
). Soft Clipping
. AC Convenience Outlets
. impedence
2S3enn
| eo heme
PHONO TUNER AUX
_6—o—o—.
PLAY
2 4 5
FRANCAS
1, Mosse 8. Bornes pour haut-perlours
2. Entree phono 8. Ecretage on doucour
3. Selectour Bobins mobile/Aimant mobile 10. Prises de courant CA
4, Entree tuner 11. Impedance
5. Entree aux
6. Entrees/Sorties-Magnetophone-
7. Sortie preampli,
entree ampli de puissance - normeal-
entree empli de puissance - labo-
SWITCHED
100W MAX
UNSWITCHED:
150W MAX
NORMAL PRE-AMP LAB SOFT
PLAY/REC REC 4N CLIPPING
3020B FRONT PANEL CONTROLS
. Treble
. Balance
} Aux/Tuner/Phono
= Somn
Stereo Amplifier 30208
PHONES
3
TREBLE
TUNER
3120 FRONT PANEL CONTROLS
Stereo Amplifier 3120
PHONES
TUNER
DEUTSCH
Erde
. Plattenspioler-Eingang
. MM/MC-Schaiter
. Rundfunkeingang
. Zusatzeingang
. Tonband-Wiedorgabe/Aufnahme
PO PONs
BNIHIGH! 40(NORMAL}
IMPEDANCE
SPEAKERS
FRANCAIS DEUTSCH
Tape
1.
Alimentation
7,
Magnetophone
1,
Netz
z
Mono
2.
Casque
decoute
8,
Mono
2.
Kopthorereusgeng
8.
.
Loudness
3.
Graves
8.
Compensateur
physiotogique
3.
Bafregier
9.
Volume
4.
Agus
10.
Volume/Equilibrage
4,
Hohenregier
10,
.
LED
Power
Meter
5,
Balance
entre
canaux
11,
indiceteur
de
puissance
par
diodes
photoluminescentes
5.
Balanceregier
nv
6. Aux Tuner/Phono 6. Zusatzgerat, Radio, Platrenspieier
PHONO TAPE
PHONO TAPE
MON:
}. _Monoschsiter
. Gehorichtige Lautstarkenregelung
MONO
Vorverstarker-Ausgang, Normal-Eingang, Labor-Eingang
. Lautsprecheranschlup
. Leutsprecherimpedenzschaiter
. Notzkabet
» Impedance
=Bopn
NAD crcconeces voraswem
MOdEL seuumeR 3120
POWER RATING 150W ac
N20V Gory Ne
i A A
a
RISQUE DE CHOC
ELECTRIQUE:
NE PAS OUVRIR
CAUTION: TO REDUCE
THE RISK OR ELECTRIC
SHOCK, DO NOT REMOVE
COVER (OR BACK),
NO USER-SEAVICEABLE
PARTS INSIDE. REFER
SERVICING TO QUALIFIED
SERVICE PERSONNEL
Tonbendschaiter
, Leutsterke
. LED.
tungsanzeige
POWER (W/8n)
5 1 20
eee
36
1
e e
VOLUME
LOUDNESS
VOLME
L-~+
(O ~=LOUDNESS

SPECIFICATIONS
POWER AMPLIFIER SECTION
Continuous average power output at 8 ohms
(minimum RMS power per channel, both channels
driven, with no more than the rated distortion)
Rated distortion (THD) 20Hz—20 KHz
Dynamic Headraam: at 8 ohms
Dynamic power (maximum short-term power Per channel)
8 ohms
4 ohms
2 ohms
T.H.D and SMPTE I.M, distortion from 250
mW to rated output
IHF I.M. (CCIF IM) and T.1.M. distortion at
rated output
Input impedance NORMAL input
LAB input
Input sensitivity for 1 Watt/25 Watts out
Frequency Response, LAB Input
Audio bandpass filtering, NORMAL input
PREAMPLIFIER SECTION
Phono input
Input impedance
Input Sensitivity (1 KHz) for 1 Watt/
25 Watts out
Signal-to-Noise Ratio with cartridge
connected, A- weighted
Input Overload
RIAA Accuracy
HIGH-LEVEL INPUTS (TUNER, AUX, TAPE)
Input Impedance
Input Sensitivity for 1 W/25 Watts out
Signal-to-Noise ratio, A-weighted
Input Overload
Frequency Response
PHYSICAL SPECIFICATIONS
Height
Width
Depth
Net Weight
Shipping Weight
Power Consumption
25 W (14 dBW)
0.02%
+3.0 dB
50W
55 W
70 W
< 0.02%
<0,02%
11.Kohm
22 Kohm
200 mV/1.0V
10 Hz—70 KHz
—3 dB at 15 Hz and
35 KHz, 12 dB/octave
47 Kohm, 100 pF
MM 0.55 mV/2.7 mV
MC 35 uV/180 nV
MM 75 dB re5mvV
MC 73 dB re 0.5 mV
MM 250 mV
MC 18 mV
+0.5 dB
20 kohm, 220 pF
35 mV/180 mV
90 dB re 1 W out
104 dB re 25 W out
>25V
20Hz—20KHz + 0.5 dB
9.6 cm (3.8 in)
42 cm (16.5 in)
24 cm (9.5 in)
5.26 Kg (11.6 Ibs.)
6.7Kg (14.7 Ibs.)
50—60 Hz, 110—120 VAC
60 Hz, 220 VAC
50 Hz, 240 VAC
150 VA

INSIDE VIEW
(4) (3)
PHONE
SW
PHONES
4
o—
FILTER
PHONO ©) ) 0 4 ow
a _| @ Ae
2° 2
TUNER ay 2
ay
Ak
x
HEADPHONE
r
Ptay
©
TAPE
SPEAKER
DIN JACK
TERMINAL
LEVEL
INDICATOR
MONO
2 mm Oo
BALANCE
q
HEADPHONE
PLay
©
| TUNER
eer > 6 |
ee

ALIGNMENT
R653
RX1
VR6
RX2
ALIGNMENT INSTRUCTIONS
GENERAL:
When servicing, in addition to checking output power, THD etc., the power output stages IDLING
CURRENT and DC OFFSET should also be checked.
if ANY WORK has been performed on the output section, checking and adjusting of IDLING
CURRENT and DC OFFSET must be done.
A. IDLING CURRENT:
Checking:
1. Set Volumecontrol to minimum, disconnect any output loads.
2. Locate and remove soldershorts across sensing resistors-R 653 (left) and R 654 (right).
3. Connect DMM or VOM (with sensitivity better than 100 mV full scale) across R 653 and R
654.
4. Turn on and read voltage. Reading should be 5 — 20mV, typically it would be around 12 mV.
1F NOT WITHIN TOLERANCES GO TO ADJUSTING:
10.
11.
12.
If within turn-on tolerances, allow unit to warm up for 5 minutes.
The voltage should then be 30 mV, tolerances + 10mV.
IF NOT WITHIN TOLERANCES GO TO ADJUSTING:
If OK, reconnect the soldershorts across R 653 and R 654.
Adjusting:
Turn off, remove bias adjusting resistors RX 1 (left) and RX 2 (right) and temporary replace
with variable resistors 2 Kohms to 5 Kohms, set the variable resistors to maximum resistance.
Turn on and read voltage acress R 653 and R 654. It should be less than 10 mV. If too high,
turn off unit immediately and check the output amplifier section, especially Q609-0611-
0613-0615-0617 left channel or Q610-0612-0614-0616-0618 right channel.
If voltage is OK upon turn-on, adjust variable resistors to read approximately 12 mV on VOM.
Leave unit on for 5 minutes and reset voltage to 30 mV. Note that it takes a little time for
readings to stabilize.
Turn off and remove variable resistors and replace with fixed resistance with exatly the same
measured value. Use resistors in series or paralell if necessary.
Recheck idling current,
Reinstall soldershorts across R 653 and R 654.
ALIGNMENT INSTRUCTIONS (continued)
Notes:
1. Failure to re-install soldershort across R653 and R 654 will result in failure at high volume.
2. Decreasing value of RX 1 and RX 2 will cause idling current to increase.
3. Too little idling current will cause ‘“Crossouer” distortion. Too much idling current will result
in overheating.
B DC OFFSET: :
1. Set Volumecontrol to minimum, disconnect any outputloads.
2. Connect DMM or VOM across each channel’s speaker terminals. eres
3. Turn on and read VOM. Reading should be 0 V.DC. Tolerance + 50mV.
Adjust VR 5 (left) or VR 6 (right) as necessary.
Notes:
1. Before adjusting VR 5 or VR 6 soften the lock paint with laquer thinner to avoid destroying
them. Secure with lock paint (nail polish) when adjustment is completed.
2. Incorrect adjustment of DC offset can create pop when inserting/removing Headphone plug.
3. Offset more than 3 V is caused by defective parts, not by misadjustments.

3020B PCB PARTS LOCATION AND WIRING DIAGRAM
240V /50Hz FOR VERSION B. BL
220V/50Hz FOR VERSION CCl
TIA/250V
\se re
_. at. r656
5 @JHe eet 220V /50Hz FOR VERSION C2
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eon
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3020B SCHEMATIC DIAGRAM
NOTES!
1 ALL RESISTORS ARE 1/6W!5%% CARBON UNLESS OTHERWISE SPECIFIED.
2 ALL DIODES ARE BAW62 UNLESS OTHERWISE SPECIFIED.
3 CAPACITANCE ARE IN uF UNLESS OTHERWISE SPECIFIED.
4 MEANS RESISTOR WITH CERAMIC TUBE STAND UPON THE P.CB.
S CIIMEANS MOUNT ON COMMON HEAT SINK.
6 XX MEANS R653 R654 WILL BE SHORTED AFTER IDLE CURRENT ALIGNMENT.
7 THE VOLTAGE SHOWN AT EACH POINTS ARE TESTED ON STATIC CONDITON.
8 ALL SW ARE ATOFF POSITION.
ChOt
427 gn2
1k
27K
@509 = PRE OUT
NOTES 2 NOTE 4: FUSES RATING
1 SW-10,bcd: POWER SW
2 SW-2a.b :PHONO SW, UL, CA SO,FL,OM
32 SW-3a.b :TUNER SW. FOR: SI, HK UK.AS.IL
\ 4 SW-La.b :AUX SW. EC,SA.
5 SW-Sa.b ‘TAPE MONITOR SW. F1,F2: 1A/250V TIA/250V.
! 6 SW-6a.b : LOUDNESS SW. F3,F4: T3A/250V 1315A/250V.
i w 7 SW-7 MONO
\ Z 8 SW-Bab :SOFT CLIPPING, .
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SW—9a.b
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3120 PCB PARTS LOCATION AND WIRING DIAGRAM
SPEAKERS
240V/50Hz FOR VERSION 8, BL
220V /50Hz FOR VERSION C,Cl
TAPE
PLAY/REC NORMAL PRE- ANP LAB
iN OUT
GROUND PHONO TUNER AUX PLAY REC IN
AC
A TIA/250V Fi
“oo 0 0} (of
B TIA/250V F2
bi o oo] [o 4%
¢ 144/250 F3
, =
1 a0 |
144/250 Fa
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0 0 0 0 3
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LOUDNESS MONO TAPE PHONO TUNER AUX
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