Grundig POWERMAX Q2, Руководство по обслуживанию

Страница: 111 / 120

111
FAILURE/ERROR ANALYSES
-------------------------------------------------------------
No audio
In case of any audio problem, not only one but
also various sources, cables and devices should
be checked against the problem. You need
to make sure that volume has not been turned
down from television settings or mute button is
not pressed.
If there is not any problems, check the loud-
speaker cables and loudspeakers on the chas-
sis; fix the problem, if any.
Before starting detailed checks, check if sound
problem is caused by headphone out. As head-
phone amp. is in sound amp., setting can be en-
abled or disabled in service menu and you can
check if the problem is caused by headphone
amp. If no sound is received from Sound IC out,
an oscilloscope can be used to check data lines
I2S and I2C in input. If no signal is observed,
then there is a problem on the main integrated
circuit. If signals are detected, you should check
IC800 and peripheral components against
problems, and check IC800 supply and see if
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 posi-
tion IC600 and peripheral components, and
at IC600 input, the availability of AU_DAC2_L
and AU_DAC2_R signals sent by main inte-
grated circuit should be checked. If you cannot
detect AU_DAC2_L and AU_DAC2_R signals
at the IC600 input, it means no sound signal
comes from main IC. If the scart output has
sound, the problem might be arising from the
audio amplifier or peripherals.
When there is no audio reception, the supply of
sound amplifier on IC800 position is checked
from V_AUDIO voltage on L804. If you cannot
detect supply, power supply should be checked
against problems.
If the amplifier is being supplied with power, Leg
13, 27, 37 of the amplifier should be checked
for 3.3V DC voltage. We should suspect the
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
(POWER_SW signal and main integrated circuit
performs the control).
Audio 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 23 and 24. Here,
the fixed 3.3V gets lower when data is being
transmitted, and thus, audio amplifier and main
integrated circuit communicate. If this value is
constantly 0V, short circuit possibility should
be checked where I2C line is connected. Cur-
rent version of the software should be installed
against software problems.
Pin 25 is the reset pin of the sound amplifier.
This pin should be high (3.3V) during the time
when TV is on. This value can be measured from
C828. If this value is low (0V), RESET_OUT sig-
nal should be checked. If this signal, which can
be checked from R812 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.