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XR-4890 SERVICE MANUAL US Model Canadian Model Photo: XR-4890 Model Name Using Similar Mechanism XR-C5100 Tape Transport Mechanism Type MG-25F-136 SPECIFICATIONS – Continued on next page – FM/AM CASSETTE CAR STEREO MICROFILM...
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SECTION 6 DIAGRAMS • IC Block Diagrams – MAIN Board – IC301 CXA2509AQ-T4 IC21 TB2118F (EL) IC351 LB1930M-TLM BUFFER 24dB 24 23 22 21 16 15 14 13 OUT1 MOTOR 120µ/70µ CONTROL DRIVE CIRCUIT CIRCUIT + – OUT2 MSMODE – BUFFER NR BIAS S-GND...
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XR-4890/4900 6-2. SCHEMATIC DIAGRAM — MAIN (1/2) SECTION — • Refer to page 15 for IC Block Diagrams. • Waveforms 2.8Vp-p 18.432MHz IC501 !™ OSC2 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.
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.
6-4. SCHEMATIC DIAGRAM — PANEL SECTION — (Page 22) Note on Schematic Diagram: • All capacitors are in µF unless otherwise noted. pF: µµF • Power voltage is dc 14.4V and fed with regulated dc power • Voltages are taken with a VOM (Input impedance 10 MΩ). •...
6-6. IC PIN FUNCTION DESCRIPTION • IC501 MASTER U-COM (MN101C12GTA1/MN101C12GTB) Pin No. Pin Name Function AVREF- – Basic voltage (- side) of AD conversion input FM/AM common signal meter A/D conversion input terminal KEYIN1 KEY (AD conversion) input KEYIN0 DBAS IN Position detecting AD input terminal of D-BASS DSTSEL Terminal for setting to select the value of destination...
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Pin No. Pin Name Function Not used AMSON “L” is output in AMS mode NROUT FOR/REV control output MTLON Metal control input/output TAPMUT Tape mute control output DOLON Dolby control input/output AMSIN Input to detect existence of song during AMS mode 57 to 75 Not used Combination stereo input and monaural output...