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Very quality copy of original service manual, which contains the circuit diagrams, PCB and lists of components, well as recommendation for calibration procedures of device, also everything else, that need for repair, tuning and use this oscilloscope.
All presented copies have high-resolution, so you can view all in detail.
This manual will very useful for simple owners and for repairers.
I recommend these manual, because myself is owner of Philips PM3216 and I need sometimes servicing these oscilloscope (principally calibrating).
Also, these document is an example of excellent design of technical documentation.
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Excellent printing quality.
A complete and very usefull service manual with all details.
GREAT SERVICE AT VERY LOW PRICE!
A+++++++++++++++++++++++++
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manual excelente completo , diagramas y esquemas bien presentados y buena calidad de imagen.
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muy buen manual completo de buena calidad de impresion preciso y detallado , muy útil para la reparación.
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The service manual is a good quality scan of the Panasonic NV-850, which is electrically identical to the Philips VR 6920, but mecanically just nearly.
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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