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1. MODIFICATION

• Countermeasure for distortion and white noise.

Improvement of MDR-RF940R Increase the value of C65 of RX
board.
Add a 22 pF capacitor in parallel with C65.
Please use the following part.
Chip ceramic capacitor 22 pF
1-163-235-11 or 1-163-235-91

SCHEMATIC  DIAGRAM

• Original Service Manual page 7.

(Location C – E, 6 – 8)

!

: Added portion

 [RX Board]

PRINTED  WIRING  BOARD

• Original Service Manual page 6.

(Location D – F, 9 – 11)

!

: Added portion

[RX Board]  – Side B –

^

@

C65

22 pF

RX Board

Содержание MDR-RF940R

Страница 1: ...nected chip component Notice that the minus side of a tantalum capacitor may be dam aged by heat Flexible Circuit Board Repairing Keep the temperature of the soldering iron around 270 C during repairing Do not touch the soldering iron on the same conductor of the circuit board within 3 times Be careful not to apply force on the conductor when soldering or unsoldering ...

Страница 2: ... 2 This section is extracted from instruction manual SECTION 1 GENERAL ...

Страница 3: ...ARD Page 4 SET 1 ear pad 2 four screws P 2 6 4 front plate R 5 housing R 3 two bosses HOUSING L SW BOARD 2 two screws P 2 6 3 screw P 2 6 5 front plate L 6 housing L 7 SW board 4 two bosses 1 ear pad HANGER R RX BOARD 5 screw PWH 2 6 6 2 two screws P 2 10 1 two screws P 2 6 3 hanger R 4 RX board 6 two head bands 7 suspender ass y HANGER L 4 screw PWH 2 6 6 2 two screws P 2 10 1 two screws P 2 6 5 ...

Страница 4: ......

Страница 5: ......

Страница 6: ... from the original one Color Indication of Appearance Parts Example KNOB BALANCE WHITE RED Parts Color Cabinet s Color Ref No Part No Description Remark Ref No Part No Description Remark 1 HEADPHONE R SECTION 11 10 9 8 7 6 5 4 3 2 1 SP2 1 1 2 3 MDR RF940R 1 4 966 797 11 PLATE R FRONT 2 4 966 794 11 HOUSING R 3 4 966 800 11 CAP R 4 4 967 909 01 SCREEN CAP 5 4 980 054 01 HANGER R 6 A 4542 441 A RX B...

Страница 7: ...SPRING BATTERY COIL 58 4 966 806 01 COVER HANGER L 59 4 966 795 01 BAND HEAD 60 4 980 053 01 HANGER L 61 4 987 590 01 TERMINAL BATTERY 62 4 987 592 01 TERMINAL COMMONNESS BATTERY 63 4 966 799 11 CAP L 64 4 966 793 11 HOUSING L 65 4 966 796 11 PLATE L FRONT 66 1 663 968 21 SW BOARD 67 4 967 909 01 SCREEN CAP 68 3 722 156 01 SPRING COMPRESSION SP1 1 505 117 21 DRIVER L CH 2 HEADPHONE L SECTION SP1 1...

Страница 8: ...5PF 5 50V C32 1 163 098 00 CERAMIC CHIP 16PF 5 50V C33 1 163 253 11 CERAMIC CHIP 120PF 5 50V C34 1 163 253 11 CERAMIC CHIP 120PF 5 50V C35 1 163 120 00 CERAMIC CHIP 130PF 5 50V C36 1 163 251 11 CERAMIC CHIP 100PF 5 50V C37 1 164 232 11 CERAMIC CHIP 0 01uF 50V C38 1 164 232 11 CERAMIC CHIP 0 01uF 50V C39 1 163 120 00 CERAMIC CHIP 130PF 5 50V C40 1 163 121 00 CERAMIC CHIP 150PF 5 50V C41 1 163 224 1...

Страница 9: ...TRANSISTOR XN1504 TX Q66 8 729 200 63 TRANSISTOR 2SC2712L TE85R Q67 8 729 200 63 TRANSISTOR 2SC2712L TE85R Q68 8 729 200 63 TRANSISTOR 2SC2712L TE85R RESISTOR CHIP CONDUCTOR R01 1 216 093 00 METAL CHIP 68K 5 1 10W R02 1 216 091 00 METAL CHIP 56K 5 1 10W R03 1 216 073 00 METAL CHIP 10K 5 1 10W R04 1 216 001 00 METAL CHIP 10 5 1 10W R05 1 216 001 00 METAL CHIP 10 5 1 10W R08 1 216 125 00 METAL CHIP ...

Страница 10: ...VARIABLE RESISTOR RV61 1 238 857 11 RES ADJ CERMET 22K RV91 1 241 853 11 RES VAR CARBON 10K 10K VOL SWITCH S41 1 692 729 21 SWITCH SLIDE CH1 CH2 VIBRATOR X01 1 767 457 11 VIBRATOR CRYSTAL 14 1875MHz 1 663 968 21 SW BOARD SWITCH S1 1 572 467 61 SWITCH PUSH 1 KEY POWER MISCELLANEOUS SP1 1 505 117 21 DRIVER L CH SP2 1 505 117 21 DRIVER R CH HARDWARE LIST 1 7 685 104 19 SCREW P 2X6 TYPE2 NON SLIT 2 7 ...

Страница 11: ...SERVICE MANUAL MDR RF940R SUPPLEMENT 1 File this supplement with the service manual AEP Model Subject 1 Modification 2 Electrical Adjustments Ver 1 0 1998 05 ...

Страница 12: ...a 22 pF capacitor in parallel with C65 Please use the following part Chip ceramic capacitor 22 pF 1 163 235 11 or 1 163 235 91 SCHEMATIC DIAGRAM Original Service Manual page 7 Location C E 6 8 Added portion RX Board PRINTED WIRING BOARD Original Service Manual page 6 Location D F 9 11 Added portion RX Board Side B C65 22 pF RX Board ...

Страница 13: ... a pick up coil See the figure 1 for measuring the local oscillation frequency of RX board Figure 1 2 Turn on the power of the adjusted transmitter 3 Input a signal of 1 kHz 50 mVrms to Lch of the transmitter for avoiding AUTO OFF 4 Set the pick up coil to the RX board as the figure 2 Figure 2 5 Confirm and adjust the frequency by the spectrum analyzer CH1 Adjust CH1 to be the following value by t...

Страница 14: ... into TMR RF940R and place the unit the point where is far from MDR RF940R and place the unit in a location where is far from by 5 m 2 Measure the DC voltage at the test point TP2 of RX board of MDR RF940R This DC voltage corresponds to the S curve voltage of FM detection characteristics as shown below If tuned frequency is in the area covered by AFC the center voltage changes when CT41 channel 1 ...

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