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perfect copy, im very satisfied, i was need the diagram over the powersupply and
the copy was very sharp
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This is exactly the service manual I needed.
Complete with all schematics, partslists, PCB layouts and alignment instructions.
This manual covers both the T-4970 en T-488F Onkyo tuner.
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IF PRINTED CIRQUIT BOARD WIRING VIEW WAS ONE TONE LIGHTER, THEN 5 STAR RANK HAS TO BE MY CHOISE.
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Very usefull, good quality drawings !
Muito útil encontrei todas as informações necessárias.
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Wanting to repair a neighbours tape recorder I needed the necessary information, it makes it easier. Although the service manual is described as "Language : English" To my dismay I found that it is entirely written in German, a language I do not understand. At least I now have the schematics which will help of sorts. I may not use this service again due to the laguage difficulty after all when it states English you do not expect it to be entirely in another language.
8-1
8-1
6-channel class-D amplifier
Basic operation of a class-D amplifier Basically, the output stage of a class-D amplifier outputs a continuous square wave swinging between positive and negative power supplies with a fixed frequency (�clock� frequency) far beyond the audible range. The duty cycle of this square wave is modulated with the audio signal. The output is followed by a low-pass filter which eliminates the clock frequency and allows only the audio signal going to the speaker. See simplified drawing below.
AMPLIFIER BOARD
TABLE OF CONTENTS Class-D Amplifier circuit description ................................................. 8-1 Exploded view + mechanical parts ................................................... 8-2 Amplifier circuit .................................................................................. 8-3 Clock Generator & connector - circuit ............................................... 8-4 Bottom view ....................................................................................... 8-5 Top view ............................................................................................. 8-6 Bottom view Part A ............................................................................ 8-7 Bottom view Part B ............................................................................ 8-8 Top view Part C ................................................................................. 8-9 Top view Part D ............................................................................... 8-10 Electrical parts list - Amplifier board ............................................... 8-11 The main disadvantage of this concept is: � The amplifier is operating with a high-frequency square wave at high amplitude and currents. This requires special precautions to prevent excessive electromagnetic radiation (EMC). Compared to a conventional power amplifier the benefits of the Class-D amplifier are: � higher effiency � lower power dissipation � smaller heatsink required � smaller mains transformer required
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