McIntosh MAC 1900 Service Manual

Page 1

11101110511

MAC 7.900

AM/FM SOLID STATE STEREO RECEIVER

SERVICE INFORMATION

FROM SERIAL N0. 4x230 T0 AL9999

McINTOSH AUDIO DIVISION, 2 CHAMBERS STREET BINGHAMTON, NEW YORK

0061 DVW

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MAC I900

PERFORMANCE

McIntosh audio power ratings are in accordance with
the Federal Trade Commission Regulation of Novem-
ber 4, 1974 concerning power output claims for ampli-
fiers used in home entertainment products.

POWER OUTPUT
55 watts minimum sine wave continuous
average power output, per channel, both
channels operating into 8 ohm load im-
pedance, which is:

29.98 volts RMS across 8 ohms
30 watts minimum sine wave continuous

average power output, per channel, both
channels operating into 16 ohms, which is:

21.9 volts RMS across 16 ohms

OUTPUT LOAD IMPEDANCE
8 ohms, or 16 ohms

RATED POWER BAND
20 Hz to 20,000 Hz

TOTAL HARMONIC DISTORTION
0.2% maximum harmonic distortion at
any power level from 250 millivolts to
rated power per channel from 20 Hz to
20,000 Hz, both channels operating

INTERMODULATION DISTORTION

0.2% if instantaneous peak power is twice rated con-
tinuous average power or less per channel with both
channels operating for any combination of frequencies
20 Hz to 20,000 Hz

FREQUENCY RESPONSE
20 Hz to 20,000 Hz +0.5 -0.5 dB at rated power

NOISE AND HUM

Power Amplifier: 95 dB below rated output
Tape Input: 90 dB below rated output

Phono Input: 76 dB below 10 mV rated power

RATINGS
DAMPING FACTOR

56 at 8 Ohms output
112 at 16 ohms output

INPUT SENSITIVITY AND IMPEDANCE
Power Amplifier: 2.5 volts, 100,000 ohms
Phono 1 and Phono 2: 2.0 mV, 47,000 ohms
Tape 1 and Tape 2: 250 mV, 250,000 ohms

TAPE OUTPUT:

Tuner: 1.0 volt at 100% modulation (FM)
Tape 250 mV with rated input at 500 Hz
Phono: 1.2 volts with 1 mV at 1000 Hz

BASS CONTROLS
:16 dB at 20 Hz

TREBLE CONTROLS
:16 dB at 20,000 Hz

L. F. FILTER
Active filter, 12 dB per octave roll off below 50 Hz,
down 18 dB at 20 Hz

H. F. FILTER
Active filter, 12 dB per octave roll off above 7,000 Hz,
down 18 dB at 20,000 Hz

PERFORMANCE LIMITS

AM TUNER SECTION
SENSITIVITY
75 UV lHF (external ant.)

SIGNAL TO NOISE RATIO
45 dB minimum lHF; 55 dB at 100% modulation

HARMONIC DISTORTION
Does not exceed 1% at 30% modulation

FREQUENCY RESPONSE
3500 Hz at -6 dB down

ADJACENT CHANNEL SELECTIVITY
30 dB minimum lHF

IMAGE REJECTION
65 dB minimum, 540 kHz-1600 kHz

FM TUNER SECTION
USEABLE SENSITIVITY
2.5 microvolts at 100% modulation (:75 kHz deviation)
for 3% total noise and harmonic distortion

SIGNAL TO NOISE RATIO
70 dB below 100% modulation

HARMONIC DISTORTION

MONO

Will not exceed 0.3% at 100% modulation :75 kHz
deviation

STEREO

Will not exceed 0.7%

AUDIO FREQUENCY RESPONSE
:1 dB 20 HZ to 15,000 Hz with standard de-emphasis
(75,;sec.) and 19,000 Hz pilot filter

CAPTURE RATIO
1.8 dB

SELECTIVITY
55 dB alternate channel selectivity IHM minmum

SPURIOUS REJECTION
90 dB IHF minimum

IMAGE REJECTION
80 dB; 88 to 108 kHz (lHF)

STEREO SEPARATION
34 dB at 1,000 HZ

SCA FILTER
50 dB rejection from 67 kHz to 74 kHz. 275 dB per
octave slope

TRANSISTOR COMPLEMENT
53 silicon field effect or bipolar transistors, 39 diodes,
3 integrated circuits, 4 thyristors

POWER REQUIREMENTS

120 volts, 50/60 Hz, 40 watts at zero signal output, 300
watts at rated output

MECHANICAL SPECIFICATIONS
SIZE
Front panel measures 16 inches wide (40.64 cm) by
5V2 inches high (13.97 cm). Chassis measures 15
inches wide (38.1 cm) by 5V8 inches high (13.02 cm)
by 15 inches deep (38.1 cm) including back panel
connectors. Knob clearance required is 11/2 inches
(3.81 cm) in front of mounting panel
FINISH
Front panel is anodized gold and black
WEIGHT

33 pounds (14.97 kg) net, 46 pounds (20.87 kg) in ship-
ping carton

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LEFT CHANNEL
POWER OUTPUT
PC BOARD 044-4
NOTE l3

RIGHT CHANNEL
POWER OUTPUT
PC BOARD 044-4"
NOTE l3

POWER SUPPLY
PC BOARD
O44 - IBO