Sharp 66CS03H Service Manual page 35

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PREVIOUS NOTES
Since most of the power amplifiers of this TV, works in switching mode (class D) a general explanation of
this system is as follows.
The system is based on moving the duty cycle of a square wave according to a modulater wave of any
shape as is shown in fig. 1 :
The way of working the signal is known as PWM (Pulse With Modulation).
After the modulated signal is amplified, a convertion to the original signal shape is made by using adequate
low pass filters (LC filters), fig. 2:
VERTICAL AMPLIFIER
Horizontal pulses are modulated (PWM mode) with the vertical saw-tooth signal (IC501 A) to get the switching
modulated signal, once it is amplified it is driven out througth the low pass filter (L501) to the deflection
coils.
E/W AMPLIFIER
As in the above case, the horizontal pulses are modulated with the E/W signal generated by the IC201. This
is done by means of the IC501 B and L605.
AUDIO POWER AMPLIFIER
The audio amplifier consists of an oscillator whose frequency and duty cycle moves according to the audio
signal. This is donde by IC303 and the switching signal is converted back into its original shape by means
ofL302/L304.
NEW SOFTWARE TO ASSIST WITH THE ADJUSTMENT OF GEOMETRY IN SERVICE MODE
AND TO SHOW UP FAILURES.
TO ASSIST WITH THE ADJUSTMENT OF GEOMETRY
• On entering the ADJUSTMENT GEOMETRY MENU of Service Mode, a self-generated card appears to
facilitate the adjustment of geometry when an adequate card is not available for this purpose.
THE SHOWING UP OF FAILURES
• If a failure is detected when the set is switched on, the stereo led will pulsate.
- One flash of the stereo led shows vertical deflection failure.
- Two consecutive flashes shows that the reading and or writing of the NVM is impossible.
- Three consecutive flahes shows a failure on MSP.
- Four consecutive flashes shows a failure on IF (1C) / Video Process (One-Chip).
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