McIntosh MR-78 Owners manual

THE McINTOSH MR 78 SOLID STATE FM/FM STEREO TUNER

Reading Time 32 Minutes

Price $1.25

Your MR 78 FM/FM Stereo Tuner
will give you many years of
pleasant and satisfactory
performance. If you have any
questions concerning the operation
or maintenance of this instrument,
please contact:

CONTENTS

CUSTOMER SERVICE

Mclntosh Laboratory Inc.
2 Chambers Street
Binghamton, New York 13903
Phone: [phone]

Take Advantage of 3 years
of FREE Factory Service . . .

Fill in the Application NOW.

Mclntosh Laboratory Incorporated guarantees this

Instrument to be capable of performance as adver­tised. We also guarantee the mechanical and elec­trical workmanship and components to be free of
defects for a period of 90 days from date of pur­chase. If such defects occur, Mclntosh Laboratory

GUARANTEE 1

INSTALLATION 2,3

HOW TO CONNECT 4,5

BACK PANEL INFORMATION 6

FRONT PANEL INFORMATION 6,7

LISTENING TO THE MR 78 TUNER 8

PERFORMANCE LIMITS 9

TYPICAL PERFORMANCE CHARTS 10,11

TECHNICAL DESCRIPTION 12,13,14

BLOCK DIAGRAM 15,16

GUARANTEE

or one of its authorized agencies will repair the
defect at no cost to the purchaser. This guarantee
does not extend to components damaged by im­proper use nor does it extend to transportation to
and from the factory or service agency.

THREE YEAR FACTORY SERVICE CONTRACT

An application for a FREE THREE YEAR FACTORY
SERVICE CONTRACT is included with this manual.
The terms of the contract are:

1. Mclntosh will provide all parts, materials and

labor needed to return the measured performance
of the instrument to the original performance
limits free of any charge. The SERVICE CON­TRACT does not cover any shipping costs to and
from the authorized service agency or the factory.

2. Any Mclntosh authorized service agency will re-

pair all Mclntosh instruments at normal service
rates. To receive the free service under the terms
of the SERVICE CONTRACT, the SERVICE CON­TRACT CERTIFICATE must accompany the instru-

ment when taken to the service agency.

3. Always have service done by a Mclntosh author­ized service agency. If the instrument is modified
or damaged, as a result of unauthorized repair the
SERVICE CONTRACT will be cancelled. Damage
by improper use or mishandling is not covered by
the SERVICE CONTRACT.

4. The SERVICE CONTRACT is issued to you as the
original purchaser. To protect you from misrepre­sentation this contract cannot be transferred to a
second owner.

5. The SERVICE CONTRACT is given to purchasers
who live In the 50 United States or Canada only.

6. For your protection Mclntosh selects Its dealers
carefully. Only one dealer in ten qualifies for a
Mclntosh franchise. To receive the SERVICE
CONTRACT your purchase must be made from a
Mclntosh franchised dealer.

7. Your completely filled in application for a SERV­ICE CONTRACT must be postmarked within 30
days of the date of purchase of the instrument.

8. To receive the SERVICE CONTRACT all informa­tion on the application must be filled in. The
SERVICE CONTRACT will be issued when the
completely filled in application is received at
Mclntosh Laboratory Incorporated In Binghamton,

New York. If the application is not received at
Mclntosh Laboratory, only the service offered
under the 90-day guarantee will apply.

Copyright © 1972 By Mclntosh Laboratory Inc.

1

clear any shelves, partitions or existing equipment
located behind the panel. With the template in place
mark the six "A" and "B" holes and four small holes
locating the corners of the cutout. Next, join the

four corner marks with pencil lines; the edge of the
template may be used as a straight edge.

2. DRILL HOLES
Holding a drill perpendicularly to the panel, drill

the six "A" and "B" holes using a 3/16 inch drill.

THE SIX HOLES MUST BE DRILLED BEFORE

MAKING THE CUTOUT.

3. SAW CUTOUT
Using a saw carefully cut the rectangular opening

on the inside of the pencilled rectangle.

4. SECURE MOUNTING STRIPS
Secure mounting strips (supplied in the hardware
package) on the inside of the cabinet panel.

Insert two screws (supplied in the hardware pack­age) into the center holes ("B" holes on the tem­plate). Use the ¾-inch long screws for panels under
½-inch or 1¼-inch screws for panels ½-inch thick
or over. Place a mounting strip on the back of the

cabinet panel as shown. Align it with the three holes

in the panel and tighten the screw. The screw head

should pull slightly into the wood panel. Attach the

other mounting strip by repeating the procedure.

It is recommended that the MR 78 tuner be mounted
in a normal or horizontal position. However, with ade­quate ventilation the tuner can be mounted in any
position.

Adequate ventilation extends the trouble-free life
of electronic instruments. It is generally found that
each 18° F rise in operating temperature reduces the
life of electrical insulation by one half. Adequate
ventilation is an inexpensive and effective means of
preventing insulation breakdown that results from
unnecessarily high operating temperatures. The direct
benefit of adequate ventilation is longer, trouble­free life.

The MR 78 tuner requires a mounting space that is

at least 15 inches deep, 17½ inches wide and 6 inches
high. Provide additional space for the air flow across
the bottom of the tuner and a means for warm air to
escape at the top.

Remove the tuner, shelf brackets, parts bag and the

mounting template from the carton. Remove tuner
from the plastic bag and place the tuner upside down
on the shipping pallet, then remove the four plastic
feet fastened to the bottom of the chassis.

The installation may be accomplished in six easy steps.

5. MOUNT PANLOC SHELF BRACKETS

Attach the Panloc shelf brackets to the cabinet panel

using four screws of the proper length. Place the
template over the mounting screws. The screws
should be centered on the "A" and "B" holes in the
template. If necessary, loosen the screws and push
the mounting brackets into alignment then retighten.

1. POSITION TEMPLATE AND MARK
Position the plastic mounting template over the
area of the cabinet panel where the MR 78 is to be
installed. Be sure that the edges of the template

6. INSTALL THE UNIT
Thread the power cord through the opening on the
cabinet panel. Carefully slide the instrument into
the opening so the rails on the bottom engage the

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track on the mounting brackets. Slide the instru­ment in until it stops at the adjust position latches.

Press the latches in and continue to slide the instru­ment until its front panel is flush with the cabinet
panel. At the bottom front corners of the instrument
are the PANLOC buttons. Depressing the PANLOC
buttons will lock the instrument firmily in the cab-

inet. Depressing the PANLOC buttons a second
time {as with a ballpoint pen) will release the in­strument. You can then slide the instrument forward
to the adjust position. Depressing the adjust position

latches will allow the instrument to be removed
from the cabinet.

3

How to Connect

AUDIO OUTPUTS

Use the FIXED OUTPUT jacks to connect to a stereo

control preamplifier or other equipment which has

its own volume control. The VOLUME CONTROL does
not affect the output of the tuner at the FIXED OUT­PUT jacks.

The output impedance at the FIXED OUTPUTS is
600 ohms. Longer cables than are normally supplied
can be used to interconnect the MR 78 with other
equipment. The length of the cable is limited by the
capacity of the cable. The total capacity must not ex­ceed 1600 pF. For instance: cables with a capacity of

32 pF per foot may be 50 feet long; 16 pF per foot cable

may be 100 feet long.

Use the FRONT PANEL CONTROLLED jacks to con­nect to equipment such as power amplifiers or tape

recorders where control of volume at the tuner is de­sired. The load impedance connected to the FRONT
PANEL CONTROLLED jacks should not be less than
47,000 ohms. There is no difference in the signal
quality or maximum output levels available at either
pair of output jacks.

An outdoor antenna is recommended for optimum

performance in all areas. In fringe (outlying) areas,

best results will be obtained with a highly directional

FM antenna used in conjunction with a rotator. Rotate
the antenna until the best reception is obtained. Con­nect the 300 ohm antenna to the 300 ANT (red)
terminals. A UHF-VHF-FM antenna is often effective
but the antenna must be designed for both FM and TV
reception. Connect the leads from the UHF-VHF-TV
antenna to the 300 ANT (red) terminals.

CONNECTING AN INDOOR DIPOLE ANTENNA

The flexible folded dipole antenna (300 ohm) is for

use in urban or high strength signal areas.

Connect the two leads from the dipole to the 300

ANT (red) terminals. The flexibility of the thin flat

wire assembly permits it to be placed under a rug,
tacked behind the stereo ... or, placed in any other

convenient location. In some cases, it may be neces-

sary to "position" the antenna for best signal recep­tion. This should be done before it is permanently lo­cated. Avoid locating this antenna next to other wires
or metal objects. This antenna may not prove effective
in houses having metal siding or metal-clad insulation.

CONNECTING AN FM ANTENNA

One of three antenna systems can be used: (1) an
outdoor FM antenna, (2) an all channel (UHF-VHF-FM)
antenna, or (3) the indoor dipole supplied with the
MR 78.

CONNECTING A 75 OHM ANTENNA

An unbalanced 75 ohm antenna can be connected to
the MR 78. A "type F" connector is used to connect
the 75 ohm coaxial cable to the back panel 75 ANT

input.

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