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/L40
MODIFICATION
Adding Protection circuit after changing the laser mechanism This will prevent further damage by ESD, power surges etc.
MODIFICATION:
After changing the laser mechanism (partno: 4102-5002-0) please perform the following modification:
1)Change R137 from 10 Ohm to 20 Ohm 1/8 W min.
2)Add a diode 1N4148 between LD and GND on J2 (cable connection to laser unit), Kathode to LD.
3)Cut trace just after collector Q101.
4)Add coil 10uH in between here.
The required parts are available from FED in a small kit, partno: 522-LASER-PROT-KIT
PRODUCTION:
Please note this modification is being implemented in running production.
The Nad 524 already has this modification except for: 1) Change R137
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