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4
INTRODUCTION
This service manual
was prepared for use by Authorized
Warranty Stations and contains
service information for Marantz Model 2240 Stereo-phonic Receiver.
Servicing information and voltage data included in this manual are intended for use by the
knowledgeable and experienced technician only. All instruction should be read carefully. No
attempt
should
be made
to proceed
without a good understanding
of the operation
in the
receiver.
The parts list furnish information by which replacement part may be ordered from the
Marantz Company. A simple description is included for parts which can be usually be obtained
through local suppliers.
1. SERVICE
NOTES
As. can be seen from the circuit diagram the chassis of Model 2240 consists of the following
units. Each unit mounted on a printed circuit board is described within the square enclosed by a
bold dotted line on the circuit diagram.
1:
(FMiFront Ends
0 ecb
ee oa
peed
ie kaeee en
ce
teas
Mounted on P.W. Board, P100
2iy
ANIME THUR ceviseicte at iceltitear boca: Sats eater pice deviated echus ameteseueye
Mounted on P.W. Board, P150
Si
CRM =P a xvetie S osadwdinns oa0 0 witha Jented
asad
ie wie
Mounted on P.W. Board, P200
Gis
MP Xistediccsies
astound ohh a h i BoraslaraPera
de oid wana o3te. pdcetet
Mounted on P.W. Board, P300
5.
ANT-ATT.
MutingUR.........
0.0.0 cece
ee eee
Mounted on P.W. Board, PU0Q1
6:.
Dolby: Level vs. ciciices una 4 Hike
oe See Bvrbine wield Wea
WA
Mounted on P.W. Board, PCO1
72
"PRONO:AMDP 42%. os aie Boel e eas, olen wae
Sie ea ee as
Mounted on P.W. Board, P400
83.
{Dial Lamp iacteiice deectae hale @ hob we ek Sols erie
eee es
Mounted on P.W. Board, PZ01
9.
Monitor, SW...
. cc
eee
eee eee een
Mounted on P.W. Board, PTO1
10.
Function Lamp ........0..
0. cee cece
eee ee eee
Mounted on P.W. Board, PY01
The.
(Pre-TOme: Amps
ie c2d os elaare. 8 «i dhe Sn ane ace eter ee SE
Mounted on P.W. Board, PEO1
AZ
"Filter SBeSW cs 5.55, ane, oie eis eek eae Cece Me, Bia avelalalonet wes
Mounted on P.W. Board, PHO1
13:
Power AMD
e:aecad ee
cee
bb ae
ew eee
en eed
eee
e's
Mounted on P.W. Board, P700
14.
Power Supply
«2.0... cee eee
eee cece eee eee eens
Mounted on P.W. Board, P800
2. AM
TUNER
The
AM
TUNER
postion
of the
2240
is composed
of one
IC circuit
(including
RF
amplifier, local oscillator, mixer, IF amplifier, and detector) and three transistors. One of them
is a signal strength indication amplifier, while the other two are amplifiers for detected audio
signals.
All components except Tuning capacitor and ferrite bar antenna are mounted on a printed
circuit board P150.
The AM signals induced in a ferrite bar antenna are applied to the input of RF amplifier (pin
12) and amplified to the level required for overcoming the conversion noises, thus giving good
S/N performance. The tuned circuits inserted in both output and input circuit of RF amplifier
assure very high image and spurious rejection performance.
Thus amplified and selected AM signals are then applied to one input of Mixer section (pin
1}. While the local oscillator voltage is injected to the other input of the section (pin 16]
through
a capacitor
C157.
Then
both
AM
signals
and
oscillating voltage
are mixed
and
converted
into 455 KHz
intermediate frequency.
The resulting IF signal is applied to the IF
transformer L153 consisting of one ceramic filter and two tuned circuits.
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