Grundig COREMAX M1 PROJECT GM, Service Manual

Page: 72 / 98

ENGLISH 72
OPERATING PRINCIPLES OF THE CIRCUIT COMPONENTS
IC900 Analog-digital tuner inte-
grated circuit
(IC-SMD Si2151-A10-
GMR)
IC900 Analog-digital tuner IC has two different
blocks. It communicates with Main IC using I2C
protocol. Thus, it locks into two set channels.
Tuner 1 block in IC is used for analog broadcast
and CVBS mark is sent to Main IC by demodu-
lation. Both tuner blocks can be used for digital
broadcasts. IF signal of desired channel is sent
to demodulator IC. IC900 integrated circuit is
supplied by 3.3V_TUN.
IC902 Satellite tuner integrated
circuit
(IC-SMD AV2018-S85QFG)
IC902 satellite tuner IC obtains inter frequency
signal of digital broadcast, similar to the tuner
in our chassis; filters this carrier frequency from
other frequencies and sends video and audio
data on it to the demodulator after loading IF on
inter-frequency. This DVB-S2 compatible tuner
also enables viewing HD broadcast from the
satellite. It operates with 3.3 V supply. And its
outputs are directly sent to the demodulator.
IC903 LNB regulator
This integrated circuit adjusts LNB voltage ac-
cording to the data received from IC through
I2C line. High band-low band, vertical-horizon-
tal selection, DiSEqC selection are all done ac-
cording to the data this integrated circuit sends
to LNB. It is supplied 12 V power.
IC800, IC801 USB supply inte-
grated circuit
(IC-SMD TPS2530D-
BVR, IC-SMD TPS2065CDBVR-2)
It is the integrated circuit that switches USB volt-
age and limits USB current. Data lines in USB
socket are directly connected to main integrated
circuit.