NAD-C540-cd-mod50001 电路图 维修手册.pdf

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1、PAGE 5-00-01 NAD 522/524/C520/C540 MODIFICATION PROBLEM: CD Player does not read disc, skips, produces scratching noise. CAUSE: The cable tie that ties the two cables to the laser together scrapes over the bottom of the unit. SOLUTION: Relocate the cable tie as shown in the below picture, its advisa

2、ble to relocate the other cables as well to avoid any contact with the other cables. Its advisable to perform this modification whenever a unit comes in for service. PRODUCTION: This modification will be implemented in production, there is no serial number information known at this moment. RadioFans

3、.CN 收音机爱 好者资料库 NAD 522/524 SERVICE HINT PROBLEM: CD Player does not read disc, skips, produces scratching noise only on some specific CDs CAUSE: The so called “playability” is affected by the use of low quality discs, scratched discs and CDRs. The problem here is not the true jitter performance of t

4、he unit itself but the capability of handling the poor quality discs without audible effects. POSSIBLE SOLUTIONS: 1) Add a ceramic capacitor 100pF at C309 position. 2) Change C122 from 1pF(NAD 522) or 5pF (NAD524) to optimum value between 2.2 and 8 pF. Note that higher value will result in lower jit

5、ter with normal CD but practically worse performance on CDRs Best balance is usually 3.3 pF 3) Re-route the cables J5 and J10; make sure they have minimal interaction with J1 and J2. THE FOLLOWING HINTS MUST NOT BE PERFORMED WITHOUT SPECIAL MEASURE EQUIPMENT. 4) Adjust TILT-screw on the laser unit f

6、or minimal Jitter with help of a Jitter meter. This is the lower mounted screw at the yellow metal plate in the corner. 5) If the laser power is above 24mW the unit will malfunction after playing for some hours. A Laser power meter is required here. Adjust laser power down to 18-22 mW. PAGE 5-99-02 RadioFans.CN 收音机爱 好者资料库