NAD-T752-avr-sur 维修电路原理图.pdf

Service Information T752 Software Upgrade (Revised) Determine software version. 1. Turn on the unit and then select an input (eg. DVD) 2. Now press the AUDIO and VIDEO buttons at the same time for 1-2 seconds. 3. The version of software will appear in the display eg. 1.06 A7 or 1.19. See note below if upgrading from 1.06 or earlier. 4. The current software in the microprocessors are 1.22 A7. Replacing the microprocessor (see attached photo) 1. Remove the top cover. 2. The front panel is easily removed .The top of the front panel is held in place with four screws on top and five on bottom. 3. Once the screws are removed pull the front panel forward and unplug the ribbon cable on your right side and the four pin connector as well. 4. Unplug the three pin and eight pin cables on the left side. 5. The microprocessor can now be removed. 6. Locate U201 and if required U202, see diagrams for reference. 7. Using a PLCC extractor tool remove the microprocessor. (Dont use a screwdriver as this may crack the socket!) 8. When inserting the microprocessor line up the dot on the top with the arrow on the socket. 9. Reconnect the cables and secure the front panel. NOTE: If you are upgrading from version 1.06 to 1.22 then you will have to replace the VFD microprocessor U202 in addition to U201. The T752 will not turn on if you only replace U201 . See the photo of U202. Reset the T752 after this procedure. RadioFans.CN 收音机爱 好者资料库 - 2 - RESETTING T752 If you experience difficulties with the T752 or are replacing both U201 and U202, then reset the unit as described below: North American units “AH” The T752 can be reset by pressing the VIDEO and the TONE DEFEAT buttons at the same time for 1-2 seconds. ALL Other Countries “C” The T752 can be reset by pressing the VIDEO and the TONE CONTROLS buttons at the same time for 1-2 seconds. Photo of U201(AVR MICROPROCESSOR) Photo of U202(VFD MICROPROCESSOR) NAD Electronics International 10/07/03 RadioFans.CN 收音机爱 好者资料库