Nad L 40 Service Information
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Page 1
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 PAGE 5-99-01
Page 2
PAGE 1-01-01 Service Tip L40 Signal display circuit change PROBLEM: Poor sensitivity of the signal strength bar graph. CAUSE: The polarity of capacitor( C739 10uF/16Vor 25V)and the pcb marking is reversed on the board. SOLUTION: Invert cpacitor( C739 10 uF/16V or 25V) by connecting its negative lead to ground and the positive lead to pin 12 of U701. PRODUCTION: This modification has been implemented in production from serial number:G13L4013553 Contact: NAD Electronics International 633 Granite Court Pickering, ON Canada L1K 3K1 Voice: 905-831-0799 FAX 905-837-6357 NAD@www.NADelectronics.com