Chrysler 4469198, 4469109, 4469108, 4469107, 4469106 Service Manual

Voltaae Tuned AM Circuits - The capacitances of varactors

U2,

changes associated

varactor fails,replace the U2 module.

change when the DC voltage applied across them

Dl,

D2, and D3,

and

the resonant frequencies of their

L-C circuits

in 'the AM tuner module

are

changed.

When a

E. Because of

combination head the radio is disassembled, the heads, shafts may be cleaned with isopropyl (rubbing) alcohol.

III.

The logic and control functions of the receiver are performed

primarily on the Audio/Logic PC Board, by the microprocessor UlOO microprocessor accepts commands

located on the front of the radio and status signals from the RF

(INFINITY ONLY). instructions to synthesizer.

fluorescent display and is located in the VF display module on

the control PC board.

local oscillator frequency and,

radio.

U.S. U.S. mode selection is accomplished by software.

operating mode,

the memory one button three times in succession. description of synthesizer pin functions, see Table l-4.

CLEANING

CIRCUIT DESCRIPTION LOGIC AND CONTROL CIRCUITS

(see Table

board,

use or 100

Voltaue Tuned FM Circuits -The capacitances of the

FM varactors, DC voltage applied across them changes and the resonant frequencies of circuits are replace the U4 module.

the

cassette

The synthesizer will tune either 200 kHz/lO

inaccessibility of the Tape Mechanism, a

and capstan cleaning tape should be used. If

l-3),

It processes the information and generates

the display

The display driver controls

kHz/9 kHz

press the SET key then the SEL key and press

located in module

changed.

and the frequency synthesizer

from the pushbutton switches

module

The frequency synthesizer controls the

steps for European use.

and

When a varactor fails,

pinch rollers and capstan

compact

module and the

thereby,

lJ4,

change when the

their

associated

U102.

disc (CD) player

frequency

the

the tuning of the

European or

To change the

vacuum

kHz

for

For a

L-C

The

1-13

TABLE 1-3.

MICROPROCESSOR

(UlOO)

PIN DESCRIPTIONS

PIN NUMBER

2 3 4 5 6

Key Input KO Key Input Key Input Key Input K3 Radio Test Pin Frequency Synthesizer Enable - Allows data

transfer to the Frequency Synthesizer 7 8 9

Beep Output

Soft mute goes low to turn on

Reset Input

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.

DESCRIPTION

Kl K2

A high on this pin for 6

Q102

11 12 13 14 15 16 17 18 19

Serial Clock

Tape Reel Input - Internally pulled up.

Off/On Key Input

C Data

C Clock

Power antenna on

N/C

External Oscillator - 1.98 MHz fed from

the synthesizer 20 21

Ground Used for display blanking

"On"

Input

The serial data clock.

Goes low for CD in.

l-14

TABLE 1-3.

MICROPROCESSOR

(UlOO)

PIN DESCRIPTIONS (Cont.)

PIN NUMBER

22 23 24

25 26 27

Cassette read enable

Cassette write enable

Mono - Goes low for force to mono Station detect Joystick enable Stereo Detect - goes low for stereo

Display Driver Enable

transferred to the vacuum fluorescent

display driver.

30 31

N/C WC

External access connected to Vcc

DESCRIPTION

goes low for station

Allows data to be

34 35 36 37 38 39 40

Goes

low for hard mute output to turn on

QlOl Power

Switch

Input - Goes high for

ignition on

Goes high for

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

PIN NUMBER

5 6

9 10

Goes high during the search mode, to

desensitize the front end to very weak stations.

Noise Reduction (high = NR on)

Serial data from the microprocessor Data clock from the microprocessor Data enable from the microprocessor Switched supply voltage which is

regulated by Input from the AM local oscillator

External bypass capacitor for the phase

detector Input from the FM local oscillator Ground

DESCRIPTION

U103,

a 5 volt regulator.

12, 13

Unswitched the clock keep alive. Keeps the

synthesizer oscillator and dividing chain active when the remaining functions of synthesizer are powered down. low power microprocessor clock driver and a time-of-day indication.

Reference oscillator which is controlled

for stability by a

capacitors and trimmer capacitor, for

accurate setting of the clock.

Reference oscillator frequency divided by two from which the microprocessor derives the instruction time.

Clock signal (50 Hz) used in the program

loop timing.

Resistor R124 sets the gain of the phase

locked loop.

supply voltage (Vcc) for

Provides a

quartz

crystal

(X101),

the

1-16

TABLE l-4.

SYNTHESIZER

(U102)

PIN DESCRIPTIONS (CONT.)

PIN NUMBER

19 20

Power-On-Reset - The power-on-reset is controlled

except when the battery voltage is disconnected.

When the ignition voltage is applied, the RC time

constant of

applied to pins 8 and 9, to a logic low. With a logic high on pin 2 and a logic low on pin

high,

of the microprocessor go high.

and

output

output.

DESCRIPTION

Charge pump output develops tuning

voltages and op-amp input. Operational amplifier output - Supplies

the tuning voltage for the RF circuits. Operational amplifier ground.

Switched supply voltage, 10 volts.

UlOl,

the output pin 3 goes high.

QlO2,

see Table l-5. Input pin 2 is always high

Cl16

and R107 causes a pulse to be

which causes pin 10 to go

Pin 10 is hard wired to pin 1.

When pin 3 goes

the microprocessor resets and pins 8 and 32

This turns on

which causes the mute pin 11 of the audio

IC'S

to go low,

therefore,

muting the

QlOl

TABLE 1-5.

INPUT A

Analog

a balance and fader input to A/D converter which places information on the Bus to allow the microcomputer to control

QUAD 2 INPUT NAND SCHMITT-TRIGGER

INPUT B

to Digital Converter - The joystick provides

OUTPUT

U105

for these functions.

U202

1-17

AM CIRCUIT

RF Stage - The AM signals received by the antenna are coupled through the series choke presents broadcast frequencies, 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

of Q2 is applied to pin 1 of U2 which contains a

varactor diode,

and transformer tuned to resonate at the selected

frequency.

Local Oscillator accomplished through pin 20 of oscillator is controlled by the synthesizer and tuned by the combination of trimmer capacitor,

in U2.

to the mixer and also the synthesizer.

Mixer varactor diode,

and transformer contained in U2. The RF and oscillator are heterodyned in 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.

Ll,

which

a high impedance to FM and shortwave

and Cl to AM antenna coil

Ul.

fixed capacitor,

The local oscillator tuning is

trimmer capacitor

The RF output

Ul.

The local

fixed capacitors,

transformer and a varactor diode

The output of the oscillator goes directly

Staae

The mixer input is

fixed capacitor,

tuned by a

trimmer capacitor

The mixer

l-18

IF amplified internally in of controlled by the IF AGC pin 17 of is tuned by T2 and coupled by Cl7 to the base of

Q3.

configuration with the output being taken off the collector of decoder U3.

AM Station Detect - When an AM signal is received, the signal meter or station detect output pin 16 of Ul Jl-11 received, high.

Detector and AM Stereo Decoder - The AM stereo

decoder chip, U3,

decode AM stereo from stations using the Motorola C-Quam

modified form of quadrature modulation which is

Stage -

Ul.

Transistor Q3 and Q4 are in the cascade

will

going

Pin 9 of Ul is the IF input which is

Ul,

and outputted on pin 10

The stage gain of the IF amplifier is

and applied to the AM stereo

cause Q7

to conduct which will result in

low.

When an AM station is

will be cut off and

Ul.

Jl-11

The IF out

will go

contains circuitry to detect and

AM stereo system.

This system uses a

not

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. this quadrature phase modulation. transmitted as normal AM.

switches to

modulated pilot signal is received.

transmitting

The (L-R) information is contained in

The (L+R) is

The chip automatically

decode stereo

when a 25 Hz, 4%

Stations

other

systems of

AM stereo

are

received in monaural,as are non-stereo stations.

The 450 pin

kHz

AM intermediate frequency is applied to

3 of u3. The chip contains an envelope

detector which detects the (L+R) portion of the

signal.

utilizing an

oscillator,

frequency, signal. kHz

and is applied to pin 17 with pin 18 being the

A phase locked loop (PLL) detector,

external

resonator controlled

which operates at eight times the IF

to detect the (L-R) portion of the

The frequency of the oscillator is 3600

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.

C20,

from which point the signal goes to pin 13,

the input of a 25 Hz

of the also the pilot detector input.

A low pass filter is formed by

bandpass

filter appears at pin 14, which is

filter.

The pilot detector

R19

and

The output

has two modes of operation. With a good signal it will

cycles of the 25 Hz pilot.

switch to stereo

after seven consecutive

When interference is present the pilot detector requires 37 consecutive cycles of pilot to switch to stereo.

the

interference

detector

input. If

Pin 12 of U3

the

detected low frequency phase modulated interference

exceeds a certain level,

prevented from switching to stereo.

the pilot detector will be

A greater

level of interference is required to switch back to

monaural if

stereo.

The most common type of interference that

the pilot

detector is already in

would require the circuitry to switch to monaural mode, station on the selected frequency. to indicate stereo.

monaural by holding pin 9 low.

function is operated,

would be the

reception

of more than one

Pin 15 goes low

The decoder can be forced to

When any tuning

pin 9 is hold low by the

microprocessor to switch the decoder to monaural

for approximately 1 second.

l-19

Detector and AM Stereo Decoder (Cont.)

During AM operation, 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).

FM CIRCUIT

FM Front End - The completely integrated FM front end, U4,

amp, and reliability are achieved by integrating the

discrete components. is hard wired to pin 13 and the output on pin 6 is the intermediate frequency. applied to frequencies of the varactor diodes, capacitor and coil combinations, stages. and the AGC input is applied to pin 3. supplies the IF output to the synthesizer. FM operation, applied to pin 5 because of the conduction of and

Q8.

performs the following functions AGC, RF

mixer,

Search sensitivity is controlled by pin 4

transistors Q5 and Q6 conduct

oscillator and IF. Increased quality

The signal from the antenna

Tuning voltage is

pin 10 to

determine the resonant

for the RF, mixer and oscillator

Pin 1

During

switched

supply

voltage

will be

Audio Detection output out of the front end is applied to pin 2 of u5. 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, the other to the frequency change detector. detected audio is amplified and outputting on pin

10.

determined by R39, C48 and C49. sensitivity is determined by R36 and C47. station detect output pin 7 turns on Q7 when a station is regulates the Vcc voltage level.

Stereo Decoder and Blend - The separation of the left and right audio is accomplished in the FM stereo decoder U6. goes in on pin 3 and is outputted as left and right audio pins 4 and 6.

kHz Vco frequency can be measured at pin 11 with a sufficiently high impedance counter through a 56K resistor or greater.

and Station Detector- The IF

The IF amplifier output has two outputs, one

one for the AF amplifier and

Operation of the frequency change detector is

Station detect

detected.

An internal

regulator

The multiplexed audio signal

The frequency of the PLL 19

pilot detector is set at pin 16.

The internal

The IC also contains a stereo

The

l-20

Stereo Decoder and Blend (Cont.)

AUDIO CIRCUIT

blend and high frequency by the IF AGC voltage at pins 7 and 5.

rolloff

circuit controlled

This

feature improves the S/N of a very weak stereo

station by gradually reducing the separation and high frequency response.

The blend threshold is

set by R43.

Filter/Amplifier

The filter/amplifier IC, U7, contains an active high pass-low pass filter which is utilized in the AM mode using input pins 15 and

17.

Internal diodes allow the chosen audio to pass but the other mode is blocked by reverse biased diodes. AM and

Dynamic accomplished in

which

reduction by varying the audio bandwidth.

The dual audio amplifier is used for both

FM.

Noise Reduction - The noise reduction is

U106.

gives up to

The IC contains circuitry

10 db of effective

noise

When there is no program material present, the audio bandwidth is electronically narrowed to cut out the mid and high frequency component of the noise. When music or speech with high frequency material

is present, the audio fidelity is not noticeably affected. opening of the bandwidth takes only 500 the bandwidth is open,

program material.

msec

after the high frequency material in the

program is

the audio bandwidth is widened so that

The

usec.

When

the noise is masked by the

The bandwidth closes back down

removed.

The program material is distinguished from the noise by a dynamic level threshold detector. the

separated from turned off, ground,

threshold at

noise.

pin 2 of

causing a constantly wide audio bandwidth, and no noise reduction. reduction is greatest on

Resistors R132 and R133 set

which

the

desired

audio is

When noise reduction is

U102

pulls pin 9 of

U106

The effect of the noise

program

material

containing quiet spots and low modulation.

Electronic - Volume, Tone, Balance and Fader - The audio inputs to the Audio Control Circuit, come selector selects the proper source and rejects the others.

(Infinity only) is applied through Cl63 to pin 8 and through Cl62 to pin 21. the tape player is applied direct to pin 12 and to pin 17.

from three sources.

The

The input

input

source

source from the CD player

for the radio is applied

U105,

The internal

source

The input source from

l-21

Electronic - Volume. Tone, Balance and Fader (Cnt)

through Cl06 to pin 10 and through The chosen input source is passed through external capacitors and on pins 13 and 16 to the DNR chip

and it comes back in on pins 14 and 15 through

C120,

is software controlled using a two wire I2 C Bus

connected to pins 1 and 28.

Bass control capacitor for the left channel as

is for the right.

control capacitor for the left channel as Cl06 is

for the right. supply voltage filtering. The internal volume, tone and balance stages are variable depending on the data on the

The

3 and 4 and two outputs for the right channel pins 25 and 26 and the variable fader control in the IC responds to the data from the microprocessor.

Power Amplifiers -

U108,

coupled to pins 2 and 13.

by the DC voltage level on pin 11. power is applied to pins 6 and 8 for bootstrapping

a feedback technique to improve linearity and also

pin 10 for +vp (supply voltage).

dual amplifiers to be used in the Bridge-Tied-Load (BTL) configuration.

is the output return.

Cl07

to pin 19.

C122; and

C119,

C121.

Capacitor

Capacitors Cl07 and

12C

Bus sent by the microprocessor.

U105

has two outputs for the left channel pins

The operation of Capacitor

Cl05

is the treble

Cl17

Cl08

are for

The audio power amplifiers

U109

and

UllO

have their inputs capacitively

Muting is accomplished

The switched

The devices are

audio

integrated

Class B

hi-fi power

Pin 9 is the output feed and pin 5

U105

is the

Cl18

U107,

E. There are four power inputs to the radio.

P107

POWER

The battery line

pin 1 maintains the memory and clock functions.

ANY INTERRUPTION OF THE UNSWITCHED POWER WILL CAUSE THE CLOCK TO REVERT BACK TO 12:00 AND THE RADIO TO REVERT TO 530

kHz

IN THE U.S. MODE.

The switched voltage is applied to L102

provide filtering and isolate power for the left side

audio outputs from the right side audio outputs.

P107

pin 2.

Chokes

LlOl

The switched

and

voltage is necessary to get a clock display and operate the

radio. controllable dimming

fluorescent display by varying the voltage. input

The rheostat dimming line

P107

pin 3 provides a

of the incandescent lamps and vacuum

The side marker

P107

pin 4 is used to lower the brightness of the vacuum

fluorescent display. 1-22

CLOCK

The osc

(X100). the clock accuracy. was 392 Hz low (196 Hz low at the clock to lose one minute per week. error oscillator.

clock function is derived from the synthesizer on-chip

illator which is stabilized by a 3.96 MHz quartz crystal

Capacitor Cl31 is a fine tuning trimmer for setting

As an example,

if the oscillator frequency

U102

14),

this would cause

This same degree of

would show up as only 79 Hz low on the AM local

See Section IV for the oscillator alignment

procedure.

Because of the surface mounted devices/components recommended that board

MECHANISM CONTROL BOARD

level maintenance

(SMD),

it is

be performed instead

of component level.

PREAMPLIFIER

Because of the surface mounted devices/components (SMD), it is recommended that board level maintenance be performed instead of component level.

IV.

ALIGNMENT

CLOCK REFERENCE FREOUENCY SETTING

Standard Method - The reference oscillator can be set without opening the radio by following this

method. a.

Turn the radio on and tune to 540 on the display.

Connect an accurately calibrated counter to pin 7 top cover, see Fig. 1-4. the AM local oscillator frequency,

(TPl)

which is accessible through the

This should display

990

kHz

when the radio is tuned to 540.

Adjust

Cl31

give a

frequency of exactly 990 capacitor board,

C131,

which is on the audio logic

can be adjusted with a long tuning tool

local

kHz +/-

oscillator

Hz.

Trimmer

through a hole in the top cover and RF board, see Fig. l-4.

l-23

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