Daewoo DV-K88 series, Руководство по обслуживанию, Страница: 16 / 129

14 CIRCUIT
4. TM BLOCK
The TUNER and MODULATOR which is separated to each module conventionally, is presently united to one block
(TM block)
(a) PLL METHOD AND I 2 C-BUS CONTROL
The RF OUTPUT channel can be varied from 22CH to 69CH by remote control using PLL method and I 2 C-BUS
control.
Moreover, SYSTEM(PAL, MESECAM), SOUND CARRIER FREQUENCY, AND TPSG(TEST PATTERN SIGNAL
GENERATOR) can be changed by remote control as well.
The P/S ratio, white clip, power saving, etc., also can be controlled only by changing a I
2 C-BUS data according to
the designer’s intention.
(b) DIGITAL AFT METHOD
Conventionally, when the frequency deviates, the variation of AFT output from IF circuit was compensated by
feedbacking it to TUNER AFT input.
On the other hand, if AFT, which is currently adopted to these models from IF circuit deviates the window range,
the VT value is changed to maintain the AFT voltage to be within window range by checking AFT(+) and AFT(-) on
MICOM.
VOLTAGE
AFT(+)
3V
WINDOW
2V
FREQ.
AFT(-)