Technics-RSM225-tape-sm 电路图 维修手册.pdf

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1、RadioFans.CN 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 RS-M225 ITEM Head azimuth adjustment Condition: Playback mode Equipment: VTVM Oscilloscope Test tape (azimuth) QZZCFM (j Tape speed Condition: Playback mode Equipment: Digital electronic counter or frequency counter Test tape- Q

2、ZZCWAT MEASUREMENT Adjustment :Adjustment : When the curve exceeds the overall frequency When the cu-ve falls below the overall frequency response chart specifications (fig. 11) as shown response chart specifications (fig. 11) as shown in fig. 14. in fig. 15. +6d8 - +4.5d8 +4dB +2d8 -. OdB l.5d8 2d8

3、 4dB 6d8 1 kHz 2kHz BdB 4kHz 8 kHz kHz Fig.14 1) Increase bias current by llXning VR7 (L-CH) and VR8 (R-CH). (See fig. 1 on page 3.) 2) Repeat steps 6 and 7 to confirm. (Proceed to steps 8, 9 and 10 if the curve is now within the charted specifications in fig. 11.) 3) If the curve still exceeds the

4、specifications (fig. 1 I), increase bias ctXrent further and repeat steps 6 and 7. 8. Place UNIT into Cr(., tape mode. 9. Ctmge test tape to QZZCRX, aid record 50Hz, lOOHz, 200Hz, 500Hz, 1 kHz, 4kHz, 8kHz, lOkHz and 12.5kHz signals. Then, playback the signals and check if the ctXve is within the lim

5、its shown in the overall frequency response chart for Cr02 tapes (fig. 16). . I kHz 2kHZ . 4kHz +6d8 +4.5dB +4d8 +2d8 OdB l.5dB -2d8 4d8 6d8 8d8 BkHz kHz Fig. 15 1) Reduce bias Cl,Jlrent by turning VR7 (L-CH) and VR8 (R-CH). 2) Repeat steps 6 and 7 to confirm. (Proceed to steps 8, 9 and 10 if the cu

6、rve is now within the charted specifications in fig. 11.) 3) If the curve still falls below the charted specifications (fig. 11), reduce bias current further and repeat steps 6 and 7. Overall frequency response chart Cr02, Metal) +4 +2 +I d8 . 0 d_B dB -2 -, (-6 -1 d8 d - iiii SO Hz 10 Hz 20 Hz / / i., . SOOHz I kHz 2kHz Flg.16 +S.Sd81 +4d8 +2dB OdB ( 2d8 2.5d 4d8 6d8 4kHz BkHz I. SkHz JO kHz