CCE HPS-1407, Service Manual, Page: 7 / 52

HPS-2007
6
2 . 1.2 Audio Residual
a) TV setup in “PP” condition.
b) Apply 60dB
µ
V signal (frequency and channel factory defined) to antenna input modulated
with white pattern at 88% and audio signal with 1kHz frequency modulated in FM with
25kHz deviation.
c) Connect an oscilloscope to power amplifier output (connect for the speaker).
d) Adjust volume to minimum.
e) Use the oscilloscope to measure peak-to-peak voltage, in Volt peak-to-peak (Vpp).
Minimum Nominal Maximum Unit
- 25 500 mVpp
2.1.3 Audio frequency response in TV’s without tone control
a) TV setup in “PP” condition.
b) Connect a color bar generator (PAL-M system) to video-in.
c) Connect to the audio input TV - an audio generator adjust to 500 mVac level, and sine
wave 1kHz.
d) Connect to the output power amplifier a resistive load with the same value of the
impedance speaker.
e) Connect na AC voltmeter over the resistive load and adjust volume control until obtain 1
Vac
) .
f) Realign the audio generator to 100 Hz sine wave at the same level ( 500 mVac).
g) Read the new voltage in the resistive load and calculate the change in dB through next
equation:
A
(100Hz)
=20 log(V
LF
/V
REF
)
The result is defined in “Decibel units “
h) Readjust the audio generator frequency to 10 kHz at the same level.
i) Read the new voltage Vh at the resistive load and calculate the change in dB through the
next equation:
A
(10kHz)
=20log(V
HF
/V
REF
)
Condition Minimum Nominal Maximum Unit
100Hz -4,00 0,00 +2,00 dB
10kHz -5,00 -1,00 +3,00 dB