Grundig 40VLE630BH, Service Manual

Page: 86 / 180

TP CHASSIS / TELEVISION
86 September 2011
there is a problem on the main integrated circuit. If signals are detected, you should
check IC500 and peripheral components against problems, and check IC500 supply
and whether MUTE is pressed on.
Besides, scart output of TV should be checked for sound. If there is no sound in scart
output, power supply of the integrated circuit at position IC900 and peripheral
components, and at IC900 input, the availability of AU_DAC0_L and AU_DAC0_R
signals sent by main integrated circuit should be checked. If you cannot detect
AU_DAC0_L and AU_DAC0_R signals at the IC900 input, it means no sound signal
comes out of the main IC. If the scart output has sound, the problem might be arising
from the sound amplifier or peripheral materials.
When there is no sound reception, the supply of sound amplifier on IC501 position is
checked from 24V of VCC_AUDIO voltage on L504. If you cannot detect power,
power supply should be checked against problems.
If the amplifier is being supplied with power, Leg 23 of the amplifier should be
checked for 3.3V DC voltage. We should suspect about main integrated circuit if
there is no 3.3V. This voltage drops down to 0V and ensures switching the amplifier
off in Stand-By mode (AMP_STB signal and main integrated circuit performs the
control).
Sound amplifier has I2C communication lines to communicate with the main
integrated circuit. Roughly, the voltage level should be below 3.3V and variable at the
Pins 33 and 34. Here, the fixed 3.3V gets lower when data is being transmitted, and
thus, sound amplifier and main integrated circuit communicate. If this value is
constantly 0V, short circuit possibility should be checked where I2C line is
connected. Current version of the software should be installed against software
problems.
Pin 31 is the reset pin of the sound amplifier. This pin should be high (3.3V) during
the time when TV is on. This value might be measured from C539 condenser. If this
value is low (0V), RESET_OUT signal should be checked. If this signal, which can be
checked from R521 resistance, is low, you may suspect that the problem rests in
software or main integrated circuit.
If all these inspections don't give any results, you may suspect that amplifier
integrated circuit has failure.