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XR-4890
SERVICE MANUAL
US Model Canadian Model

Photo: XR-4890

Model Name Using Similar Mechanism Tape Transport Mechanism Type

XR-C5100 MG-25F-136

SPECIFICATIONS

­ Continued on next page ­

FM/AM CASSETTE CAR STEREO
MICROFILM

SECTION 6 DIAGRAMS
· IC Block Diagrams ­ MAIN Board ­

IC301 IC351 LB1930M-TLM

CXA2509AQ-T4
LINEOUT2 TAPEIN2 PBOUT2 AUXIN2 PBEQ2 MSSW DIREF

IC21

TB2118F (EL)
AM CP OUT FM CP OUT A-GND D-GND AM IN FM IN

GND

NC
24dB

VCC 1 NC 2 IN1 3 IN2 4

VDD

REG

VCC

IFC

VT

10 NC BUFFER CONTROL CIRCUIT BUFFER MOTOR DRIVE CIRCUIT 9 OUT1 8 NC 7 OUT2 6 P-GND

24 23

XI

30

29

28 27

26

25

24

23 22 21

22 21

20

19

18

17 AMP

16 15 14 13

120µ/70µ T2 ­ + PBFB2 31 PBRIN2 32 PBREF2 33 F2 TAPE EQ FWD/RVS NR BIAS X1 TAPE/AUX + ­

+
VCC 4BIT SWALLOW COUNTER SEEK/RECP PRESCALLER 12BIT PROGRAMMABLE COUNTER ­ + + ­

VDD AMP

NC

20 MSMODE MS MODE 19 DRSW 18 TAPESW 17 INSW 16 NC

S-GND 5

REGULATOR SEEK/RECP

AMP

+

PBFIN2 34

PHASE COMPARATOR

SIG

VCT 35 PBGND 36
20BIT IF COUNTER

VCT + LPF

VCC + ­ F3 X1

REF

MS ON/ 15 NC OFF DETECT 14 MSOUT

OSCILLATOR

REFERENCE DIVIDER

40BIT SHIFT REGISTER 18BIT 22BIT

PBFIN1 37 PBREF1 38 PBRIN1 39 PBFB1 40 T1 ­ + + ­ F1

13 DGND

ON/OFF BUFFER

18BIT

12 MSTC 11 G1FB

VDD2

SERIAL INTERFACE

I/O PORT

OUTPUT PORT

120µ/70µ 1 2 3 4 5 6 7

24dB 8 9 10

TAPEIN1 AUXIN1

LINEOUT1

PBOUT1

MSLPF

PBEQ1

1

2

3 4 5 6

7

8

9

10 11

12

CE DIN CK DOUT

I/O-1

XO

SR

I/O-2

OUT-1

OUT-2

VDD2

OSC

IC661 IC331 TDA7462D
28 27 26 25 24 23 SE3L SE3R MUTE SDA SCL PAUSE

BA3918-V2

REGULATOR

PAUSE DETECT INPUT GAIN & AUTO ZERO TREBLE/ BASS CONTROL CIRCUIT FRONT FADER

HP

LP FRONT FADER 21 OUT FR

INPUT MULTIPLEXER & MIXING STAGE

COMPANDER
1 2 3 4 5 6 7 8 9 10 11 12

MODE2 MODE1 STB

REAR SIDE SELECTOR

REAR FADER LOUDNESS CONTROL CIRCUIT

COM

AMP

20 OUT RL

INPUT GAIN

REAR FADER

19 OUT RR

IC751

TDA7385

BEEP

SUBWOOFER LP

FADER 18 SUBOUT+ 17 SUBOUT­ SDA

SUBWOOFER OUT IIC BUS

DIGITAL CONTROL CIRCUIT

SCL 16 VDD 15 GND
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

­ 15 ­

TAB PW-GND OUT2­ ST-BY OUT2+ Vcc1 OUT1­ PW-GND1 OUT1+ SVR IN1 IN2 S-GND IN4 IN3 AC-GND OUT3+ PW-GND3 OUT3­ Vcc2 OUT4+ MUTE OUT4­ PW-GND4 DIAGNOSTICS OUT

CREF 14

POWER SUPPLY

­ 16 ­

GND

VDD

NC

VCC

ANT

AM

FM

+ ­

+ ­

+ ­

+ ­

SE1L SE1R MD+ MD­ CDL+ CDL­ CDR­ CDR+ PDR PDGND PDL SE2L SE2R

1 2 3 4 5 6 7 8 9 10 11 12 13

FRONT SIDE SELECTOR

LOUDNESS CONTROL CIRCUIT

VOLUME CONTROL CIRCUIT

SOFT MUTE

VOICE BANDPASS

22 OUT FL

OVER VOLTAGE PROTECT

G2FB

NC

VCC

NC

XR-4890/4900

6-2. SCHEMATIC DIAGRAM -- MAIN (1/2) SECTION -- · Refer to page 15 for IC Block Diagrams.

· Waveforms

1
2.8Vp-p

18.432MHz

IC501 !TM OSC2

2
5.0Vp-p

32.768MHz

IC501 !§ XO

Note on Schematic Diagram: · All capacitors are in µF unless otherwise noted. pF: µµF 50 WV or less are not indicated except for electrolytics and tantalums. · All resistors are in and 1/4 W or less unless otherwise specified. ˘ · : internal component. · C : panel designation. · U : B+ Line. · Power voltage is dc 14.4V and fed with regulated dc power supply from ACC and BATT cords. · Voltage and waveforms are dc with respect to ground under no-signal conditions. no mark : FM < > : TAPE PLAYBACK : Impossible to measure · Voltages are taken with a VOM (Input impedance 10 M). Voltage variations may be noted due to normal production tolerances. · Waveforms are taken with a oscilloscope. Voltage variations may be noted due to normal production tolerances. · Circled numbers refer to waveforms. · Signal path. F : FM f : AM (MW) E : TAPE PLAYBACK

(Page 21, 22)

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XR-4890/4900
6-3. SCHEMATIC DIAGRAM -- MAIN (2/2) SECTION -- · Refer to page 15 for IC Block Diagrams.

(Page 19, 20)

Note on Schematic Diagram: · All capacitors are in µF unless otherwise noted. pF: µµF 50 WV or less are not indicated except for electrolytics and tantalums. · All resistors are in and 1/4 W or less unless otherwise specified. ˘ · : internal component. · C : panel designation. · U : B+ Line. · Power voltage is dc 14.4V and fed with regulated dc power supply from ACC and BATT cords. · Voltage and waveforms are dc with respect to ground under no-signal conditions. no mark : FM < > : TAPE PLAYBACK : Impossible to measure · Voltages are taken with a VOM (Input impedance 10 M). Voltage variations may be noted due to normal production tolerances. · Waveforms are taken with a oscilloscope. Voltage variations may be noted due to normal production tolerances. · Circled numbers refer to waveforms. · Signal path. F : FM f : AM (MW) E : TAPE PLAYBACK · Abbreviation CND : Canadian model.

(Page 25)

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6-4. SCHEMATIC DIAGRAM -- PANEL SECTION --

(Page 22)

Note on Schematic Diagram: · All capacitors are in µF unless otherwise noted. pF: µµF 50 WV or less are not indicated except for electrolytics and tantalums. · All resistors are in and 1/4 W or less unless otherwise specified. ˘ · : internal component. · C : panel designation. · U : B+ Line.

· Power voltage is dc 14.4V and fed with regulated dc power supply from ACC and BATT cords. · Voltage and waveforms are dc with respect to ground under no-signal conditions. no mark : FM < > : TAPE PLAYBACK : Impossible to measure

· Voltages are taken with a VOM (Input impedance 10 M). Voltage variations may be noted due to normal production tolerances. · Waveforms are taken with a oscilloscope. Voltage variations may be noted due to normal production tolerances. · Circled numbers refer to waveforms.

· Signal path. F : FM f : AM (MW) E : TAPE PLAYBACK

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6-6. IC PIN FUNCTION DESCRIPTION
· IC501 MASTER U-COM (MN101C12GTA1/MN101C12GTB) Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 Pin Name AVREFVSM KEYIN1 KEYIN0 DBAS IN DSTSEL FUNC-SEL NCO RCIN0 AVREF+ VDD OSC OUT OSC IN GND XT IN XT OUT GND RCIN1 SYSRST BUSON UNISO UNISI UNICKO UNICKI NCO KEYACK NOSESW BU_IN SIRCS TELMUT TESTIN RAMBU RESET VOLMUT BEEP AMPMUT AMPON PLLCKD PLLCE PLLSO PLLSI LCDSD LCDCE LCDCKD VOLSO NCO VOLCKO ACCIN MUT I/O ­ I I I I I I O I I ­ ­ ­ ­ ­ ­ ­ I O O O I O I O I I I I I I I I O O O O O O O I O O O O O O I O Function Basic voltage (- side) of AD conversion input FM/AM common signal meter A/D conversion input terminal KEY (AD conversion) input Position detecting AD input terminal of D-BASS Terminal for setting to select the value of destination Function selecting (AD conversion) input Not used Rotary commander (AD conversion) input Basic voltage (+side) of AD conversion input Power supply Radiator (18.432 MHz) connecting terminal Ground Sub clock (for clock) radiator (32 kHz) connecting terminal Ground Rotary commander shift input SYSTEM RESET control output BUS ON control output Serial data output Serial data input Serial clock output Serial clock input Not used Key input acknowledge Removing/attaching front panel detection input BACK-UP detection input terminal Remote control input TELEPHONE MUTE detection input Test mode setting input terminal Reset detection input of RAM Reset input terminal Not used Control output for buzzer Power amplifier mute control output terminal Power amplifier STANDBY control terminal PLL CLK output terminal PLL CE output terminal PLL DATA output terminal PLL DATA input terminal LCD serial data output LCD chip enable output terminal LCD serial clock output Electrical volume serial data output Not used Electrical volume serial data output Accessory power supply detection input System MUTE control output

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Pin No. 50 51 52 53 54 55 56 57 to 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 to 99 100 NCO

Pin Name AMSON NROUT MTLON TAPMUT DOLON AMSIN NCO ST SD_IN REIN 1 REIN 0 AD ON PW SEL ILLON REL POS3 POS2 POS0 POS1 LM LOD LM EJ TAPON CM ON PW ON FM ON TUNON DAVSS NCO DAVDD

I/O O O O I/O O I/O I O I/O I I I O I O I I I I I O O O O O O O ­ O ­ Tape position signal detection input Not used "L" is output in AMS mode FOR/REV control output Metal control input/output Tape mute control output Dolby control input/output

Function

Input to detect existence of song during AMS mode Not used Combination stereo input and monaural output SIGNAL DETECTOR input terminal Rotary encoder input terminal Power supply control output of AD conversion Power selection initialise Illumination power supply control output Input to detect rotation of reel table

Loading motor control output (to a direction of loading) Loading motor control output (to a direction of ejection) TAPE power supply control output When `on' is output, "H" is output, otherwise when `off' is output, "L" is output. Capstan motor control signal output terminal of TAPE System power supply control output FM power supply control output terminal TUNER power supply control output terminal Ground Not used Not used (Power supply for DA converter)

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