Nad 524 Service Manual

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, it’s advisable to relocate the other cables as well to
avoid any contact with the other cables.

It’s 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.

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NAD 522/524

SERVICE HINT

PROBLEM:

CD Player does not read disc, skips, produces scratching noise only on some specific CD’s

CAUSE:

The so called “playability” is affected by the use of low quality discs, scratched discs and CDR’s.
The problem here is not the true jitter performance of the 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 jitter with normal CD but practically worse performance on
CDR’s
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 for 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.

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