Nad C-300 Service Manual

December 2005

NAD

SERVICE MANUAL

C 300

STEREO

C 300

STEREO

AMPLIFIER

AMPLIFIER

”are critical with regard to the risk of fire and electric shock. Replace

TABLE OF CONTENTS

DESCRIPTION PAGE

REAR PANEL/FRONT PANEL VIEW………………………………………...3

SPECIFICATIONS…………………………………………………………….4-5

DISASSEMBLY INSTRUCTIONS……………………………………………..6

ALIGNMENT PROCEDURE……………………………………………………7

PCB LAYOUT………………………………………………………………. 8-9

SCHEMATIC DIAGRAM…………………………………………………..10

WIRING DIAGRAM…………………………………………………………….11

IC BLOCK DIAGRAM…………………………………………………….…...12

ELECTRICAL PARTS LIST………………………………………………13-16

EXPLODED VIEW PARTS LIST……………………………………………..17

EXPLODED VIEW……………………………………………………………..18

PACKING DIAGRAM………………………………………………………….19

_SERVICE SAFETY PRECAUTIONS_

1. Replacing the fuses
CAUTION: FOR CONTINUED PROTECTION AGAINST THE RISK OF FIRE, REPLACE ONLY WITH
DESIGNATED TYPE OF FUSE FOR *AH, *B1, *B AND *C VERSIONS.

Reference No Part Number Description

F701—F702 20-00500-25 T5AL250V Fuse
F703—F704 20-00050-25 T0.5AL250V Fuse

NOTE:
<*AH> : USA, CANADIAN MODEL ONLY.
<*B> : UK MODEL ONLY.
<*B1> : AUSTRALIAN MODEL ONLY.
<*C> : EUROPEAN MODEL ONLY.

2. Safety check out
(Only U.S.A. Model)
Before returning the product to the customer, make leakage current or resistance measurements to
determine that exposed parts are acceptably insulated from the supply circuit.

Parts marked with the symbol “
only with parts recommended by the manufacturer.

!

SPECIFICATIONS

POWER AMPLIFIER SECTION

STEREO MODE
CONTINUOUS AVERAGE POWER OUTPUT INTO 8 OHMS…….…………25W
(Min. Power per channel, 20Hz-20kHz, both channels driven,
with no more than rated distortion)
Rated impedance……………………………………………………………….….4-8ohms
Rated distortion (THD 20Hz-20kHz)………………….………………………….0.03%
Clipping power (maximum continuous power per channel) ..…………………30W
IHF dynamic headroom at 8 ohms………………….……………………………+2.4dB
IHF dynamic power

8 ohms: ………………….…………………………..43W
4 ohms: ………………….…………………………..65W
2 ohms: ………………….…………………………..90W
Damping factor (ref. 8 ohms 50Hz) ………………….…………………………..>100
Peak undistorted O/P current (into 0.1—0.5ohms, both channels running) …40A
Frequency response at 20Hz-20kHz (Tone Control in)…….…………………..0±0.5dB

Frequency response at 10Hz/70kHz………………………....…………………..-2dB

THD…………………………………………….…………………………………….<0.03%
(Total Harmonic Distortion, 20Hz-20kHz, from 250mW to rated output)
SMPTE I.M. …………………………………………….…………………………..<0.03%
(IM distortion, 60Hz + 7kHz, 4:1, from 250mW to rated output)
IHF I.M. (CCIF IM distortion, 19+20kHz at rated output) and DIM 100………<0.03%

PREAMPLIFIER SECTION

Line Level Inputs (Disc, CD, Video, Aux, Tuner, Tape 1, Tape 2)
Input impedance (R and C) …………………………………………….………..210kohms//320pF
Input sensitivity (ref. rated power) ……………………………………….……...200mV
Maximum input level……………………………………….………………………5V rms
Signal /Noise ratio, A-weighted…………………………….……………………..>100dB ref.1W
>114dB ref. rated power
Maximum Output Level (Tape 1&2)…………………………….………………..5V rms

TONE CONTROLS

Treble (at 10kHz)…………………………….…………………………………….±6dB
Bass (at 100Hz) …………………………….……………………………………..±5dB

PHYSICAL SPECIFICATION

Dimensions in mm (Width×Height×Depth) …………………………………...435×95×325
Net weight…………………………….………………………………………….…5.0kg
Shipping Weight……………………….…………………………………………...6.2kg
Power Consumption(at 2×50W/4ohms output) 230V 50Hz………………….185W

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ALIGNMENT PROCEDURE

A. OUTPUT OFFSET VOLTAGE

1.Push Power on, preheat unit for 5 minutes.

2.Connect the DC Millivoltmeter to L Channel speaker output terminals or TP5 and

TP7, adjust VR301 to get a reading of 0V±30mV.

3.Connect the DC Millivoltmeter to R Channel speaker output terminals or TP6 and

TP8, adjust VR401 to get a reading of 0V±30mV.

B. IDLING CURRENT

1.Connect the DC Millivoltmeter across D305, adjust VR302 for 160 -- 180mV reading

on meter.

2.Connect the DC Millivoltmeter across D405, adjust VR402 for 160 -- 180mV reading

on meter.

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