Chrysler 4469106 User manual

4.
Voltaae Tuned AM Circuits - The capacitances of
varactors Dl, D2, and D3, in 'the AM tuner module
U2,
change when the DC voltage applied across them
changes
and
the resonant frequencies of their
associated L-C circuits are
changed. When a
varactor fails,replace the U2 module.
5.
Voltaue Tuned FM Circuits - The capacitances of the
FM varactors,located in module
lJ4, change when the
DC voltage applied across them changes and the
resonant frequencies of their associated L-C
circuits are changed.
When a varactor fails,
replace the U4 module.
E. CLEANING
Because of
the
combination head inaccessibility of the Tape Mechanism, a and capstan cleaning tape should be used. If
the radio is disassembled, the heads,pinch rollers and capstan
shafts may be cleaned with isopropyl (rubbing) alcohol.
III. CIRCUIT DESCRIPTION
A. LOGIC AND CONTROL CIRCUITS
The logic and control functions of the receiver are performed
primarily on the Audio/Logic PC Board, by the microprocessor
UlOO (see Table l-3),
and the frequency synthesizer U102. The
microprocessor accepts commands from the pushbutton switches
located on the front of the radio and status signals from the
RF
board, cassette module
and compact
(INFINITY ONLY). disc (CD) player
instructions to It processes the information and generates
the display module and the
synthesizer. frequency
The display driver controls
the
vacuum
fluorescent display and is located in the VF display module on
the control PC board. The frequency synthesizer controls the
local oscillator frequency and,
radio.
thereby, the tuning of the
The synthesizer will tune either 200 kHz/lO
kHz for
U.S.
use or 100 kHz/9 kHz steps for European use.
U.S. mode selection is accomplished by software. European or
operating mode, To change the
press the SET key then the SEL key and press
the memory one button three times in succession. For a
description of synthesizer pin functions, see Table l-4.
1-13

TABLE 1-3. MICROPROCESSOR (UlOO) PIN DESCRIPTIONS
PIN NUMBER
DESCRIPTION
1
Key Input KO
2
Key Input Kl
3 Key Input K2
4 Key Input K3
5 Radio Test Pin
6 Frequency Synthesizer Enable - Allows data
transfer to the Frequency Synthesizer
7 Beep Output
8 Soft mute goes low to turn on Q102
9 Reset Input
- A high on this pin for 6
usec. while the oscillator is running
resets the device.
10
Serial data input and output - Provides
serial data to the display driver and
frequency synthesizer.
11 Serial Clock
- The serial data clock.
12
Tape Reel Input - Internally pulled up.
13
Off/On Key Input
14 CD "On" Input
- Goes low for CD in.
15 I2 C Data
16
I2 C Clock
17
Power antenna on
18
N/C
19
External Oscillator - 1.98 MHz fed from
the synthesizer
20
Ground
21
Used for display blanking
l-14

TABLE 1-3. MICROPROCESSOR
(UlOO) PIN DESCRIPTIONS (Cont.)
PIN NUMBER DESCRIPTION
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Cassette read enable
Cassette write enable
AM Mono - Goes low for force to mono
Station detect
- goes low for station
Joystick enable
Stereo Detect - goes low for stereo
Display Driver Enable
- Allows data to be
transferred to the vacuum fluorescent
display driver.
N/C
WC
External access connected to Vcc
Goes low for hard mute output to turn on
QlOl
Power Switch Input - Goes high for
ignition on
Goes high for FM
Goes high for AM
Strobe 3
Strobe 2
Strobe 1
Strobe 0
Voltage Supply, Vcc + 5VDC
l-15

TABLE l-4.
SYNTHESIZER (U102) PIN DESCRIPTIONS
1-16
PIN NUMBER
DESCRIPTION
1
Goes high during the search mode, to
desensitize the front end to very weak
stations.
2
Noise Reduction (high = NR on)
3 Serial data from the microprocessor
4 Data clock from the microprocessor
5
Data enable from the microprocessor
6 Switched supply voltage which is
regulated by
U103,
a 5 volt regulator.
7 Input from the AM local oscillator
8 External bypass capacitor for the phase
detector
9 Input from the FM local oscillator
10 Ground
11 Unswitched supply voltage (Vcc) for
the clock keep alive. Keeps the
synthesizer oscillator and dividing chain
active when the remaining functions of
the
synthesizer are powered down. Provides a
low power microprocessor clock driver and
a time-of-day indication.
12, 13
Reference oscillator which is controlled
for stability by a quartz crystal (X101),
capacitors and trimmer capacitor, for
accurate setting of the clock.
14 Reference oscillator frequency divided by
two from which the microprocessor derives
the instruction time.
15
16
Clock signal (50 Hz) used in the program
loop timing.
Resistor R124 sets the gain of the phase
locked loop.

TABLE l-4.
SYNTHESIZER (U102) PIN DESCRIPTIONS (CONT.)
PIN NUMBER
DESCRIPTION
17
Charge pump output develops tuning
voltages and op-amp input.
18
Operational amplifier output - Supplies
the tuning voltage for the RF circuits.
19
Operational amplifier ground.
20
Switched supply voltage, 10 volts.
1.
Power-On-Reset - The power-on-reset is controlled
by
UlOl,
see Table l-5. Input pin 2 is always high
except when the battery voltage is disconnected.
When the ignition voltage is applied, the RC time
constant of Cl16 and R107 causes a pulse to be
applied to pins 8 and 9,which causes pin 10 to go
to a logic low.
Pin 10 is hard wired to pin 1.
With a logic high on pin 2 and a logic low on pin
1,
the output pin 3 goes high.
When pin 3 goes
high,
the microprocessor resets and pins 8 and 32
of the microprocessor go high.
This turns on QlOl
and QlO2,
which causes the mute pin 11 of the audio
output IC'S to go low, therefore,
muting the
output.
TABLE 1-5.
QUAD 2 INPUT NAND SCHMITT-TRIGGER
INPUT A INPUT B OUTPUT
2. Analog to Digital Converter - The joystick provides
a balance and fader input to A/D converter U202
which places information on the Bus to allow the
microcomputer to control U105 for these functions.
1-17

B.
AM CIRCUIT
1.
RF Stage - The AM signals received by the antenna
are coupled through the series choke Ll, which
presents
a high impedance to FM and shortwave
broadcast frequencies,
and Cl to AM antenna coil Tl
which transformer couples the RF signal to the gate
of Ql a J-FET RF amplifier. Transistor Q2 the
second RF amplifier has its conduction controlled
by the RF amplifier AGC pin 1 of Ul. The RF output
of Q2 is applied to pin 1 of U2 which contains a
varactor diode, fixed capacitor,
trimmer capacitor
and transformer tuned to resonate at the selected
frequency.
2. Local Oscillator - The local oscillator tuning is
accomplished through pin 20 of Ul. The local
oscillator is controlled by the synthesizer and
tuned by the combination of
fixed capacitors,
trimmer capacitor,
transformer and a varactor diode
in U2. The output of the oscillator goes directly
to the mixer and also the synthesizer.
3. Mixer Staae - The mixer input is tuned by a
varactor diode, fixed capacitor, trimmer capacitor
and transformer contained in U2. The RF and
oscillator are heterodyned in the mixer. The mixer
output pin 7 of Ui is tuned to resonate at the IF
or difference frequency by FL1 and applied to the
IF input pin 9 of Ul through C8.
4. IF Stage - Pin 9 of Ul is the IF input which is
amplified internally in Ul, and outputted on pin 10
of Ul.
The stage gain of the IF amplifier is
controlled by the IF AGC pin 17 of Ul.
The IF out
is tuned by T2 and coupled by Cl7 to the base of
Q3.
Transistor Q3 and Q4 are in the cascade
configuration with the output being taken off the
collector of
Q4 and applied to the AM stereo
decoder U3.
5.
AM Station Detect - When an AM signal is received,
the signal meter or station detect output pin 16 of
Ul will cause Q7 to conduct which will result in
Jl-11 going
low. When an AM station is
not
received,
Q7 will be cut off and Jl-11 will go
high.
6.
Detector and AM Stereo Decoder - The AM stereo
decoder chip, U3,contains circuitry to detect and
decode AM stereo from stations using the Motorola
C-Quam AM stereo system. This system uses a
modified form of quadrature modulation which is
l-18

6.
Detector and AM Stereo Decoder (Cont.)
compatible with monaural
receivers. The phase
modulation components of a quadrature signal are
extracted and used to phasemodulate the broadcast
transmitter.
The (L-R) information is contained in
this quadrature phase modulation. The (L+R) is
transmitted as normal AM. The chip automatically
switches to decode stereo when a 25 Hz, 4%
modulated pilot signal is received.
Stations
transmitting other systems of AM stereo
are
received in monaural,as are non-stereo stations.
The 450 kHz AM intermediate frequency is applied to
pin 3 of u3. The chip contains an envelope
detector which detects the (L+R) portion of the
signal. A phase locked loop (PLL) detector,
utilizing an
external resonator controlled
oscillator, which operates at eight times the IF
frequency, to detect the (L-R) portion of the
signal. The frequency of the oscillator is 3600
kHz and is applied to pin 17 with pin 18 being the
feedback pin.
The stereo pilot signal is contained in the phase
modulated (L-R) portion of the signal. This signal
is controlled by an internal AGC and outputted on
pin 11. A low pass filter is formed by R19 and
C20, from which point the signal goes to pin 13,
the input of a 25 Hz
bandpass filter. The output
of the bandpass filter appears at pin 14, which is
also the pilot detector input. The pilot detector
has two modes of operation. With a good signal it
will switch to stereo
after seven consecutive
cycles of the 25 Hz pilot. When interference is
present the pilot detector requires 37 consecutive
cycles of pilot to switch to stereo. Pin 12 of U3
is the interference
detector input. If
the
detected low frequency phase modulated interference
exceeds a certain level,
the pilot detector will be
prevented from switching to stereo. A greater
level of interference is required to switch back to
monaural if the pilot detector is already in
stereo.
The most common type of interference that
would require the circuitry to switch to monaural
mode,
would be the
reception of more than one
station on the selected frequency.
Pin 15 goes low
to indicate stereo.
The decoder can be forced to
monaural by holding pin 9 low.
When any tuning
function is operated,
pin 9 is hold low by the
microprocessor to switch the decoder to monaural
for approximately 1 second.
l-19

6. Detector and AM Stereo Decoder (Cont.)
During AM operation,
transistors Q5 and Q6 conduct
to apply the regulated 10 volts to pin 6 of U3.
The AM audio outputs pin 7 (left) and pin 8 (right)
are applied to the filter/Amp IC (U7).
C. FM CIRCUIT
1. FM Front End - The completely integrated FM front
end, U4,
performs the following functions AGC, RF
amp,
mixer,
oscillator and IF. Increased quality
and reliability are achieved by integrating the
discrete components.
The signal from the antenna
is hard wired to pin 13 and the output on pin 6 is
the intermediate frequency.
Tuning voltage is
applied to pin 10 to
determine the resonant
frequencies of the varactor diodes, capacitor and
coil combinations,
for the RF, mixer and oscillator
stages. Search sensitivity is controlled by pin 4
and the AGC input is applied to pin 3. Pin 1
supplies the IF output to the synthesizer.
During
FM operation, switched supply voltage will be
applied to pin 5 because of the conduction of
Q9
and Q8.
2. Audio Detection and Station Detector - The IF
output out of the front end is applied to pin 2 of
u5. The IF amplifier output has two outputs, one
to the level detector for AGC output pin 6 and the
other to a buffer amplifier. The buffered IF
output on pin 16 is connected to pin 15 by R37.
Pins 14 and 15 are the inputs to the peak detector
which has two outputs, one for the AF amplifier and
the other to the frequency change detector. The
detected audio is amplified and outputting on pin
10. Operation of the frequency change detector is
determined by R39, C48 and C49. Station detect
sensitivity is determined by R36 and C47. The
station detect output pin 7 turns on Q7 when a
station is
detected. An internal regulator
regulates the Vcc voltage level.
3.
Stereo Decoder and Blend - The separation of the
left and right audio is accomplished in the FM
stereo decoder U6.
The multiplexed audio signal
goes in on pin 3 and is outputted as left and right
audio pins 4 and 6. The frequency of the PLL 19
kHz pilot detector is set at pin 16. The internal
Vco frequency can be measured at pin 11 with a
sufficiently high impedance counter through a 56K
resistor or greater.
The IC also contains a stereo
l-20