NAD-T752-avr-si2 维修电路原理图.pdf

Service Information T752Circuit ChangePROBLEM: Muted audio with certain dvd players using the coaxial/opticalinputs .CAUSE: The incoming digital signal isnt recognized as a valid signal.Certain DVD players set the “v” bit incorrectly.SOLUTION: Upgrade software so the receiver will recognise the incomingsignal. Follow the instructions below for upgrading.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 1-2seconds.3. The version of software will appear in the display like, 1.04 A6 or 1.04 A7.4. The A6 or A7 designation determines which microprocessor to use.5. The current software in the microprocessors are 1.06 A6 or 1.06 A7.6. The receiver will not turn on if you try using A6 microprocessors for unitswhich use A7 software.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 inplace with four screws on top and five on bottom.3. Once the screws are removed pull the front panel forward and unplugthe 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, see diagram 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 thearrow on the socket.9. Reconnect the cables and secure the front panel.RadioFans.CN 收音机爱 好者资料库RESETTING T752If you experience difficulties with the T752 after this procedure thenreset the unit as described below,North American units “AH”The T752 can be reset by pressing the VIDEO and the TONEDEFEAT buttons at the same time for 1-2 seconds.ALL Other Countries “C”The T752 can be reset by pressing the VIDEO and the TONECONTROLS buttons at the same time for 1-2 seconds.Photo of U201Contact:NAD Electronics International633 Granite CourtPickering, ON Canada L1K 3K1Voice: 905-831-0799 FAX 905-837-6357 RadioFans.CN 收音机爱 好者资料库