Hitachi C28W440N, Service Manual

Page: 11 / 63

11
(1). Enough margin is available to tune down to 45.25 MHz.
(2). Enough margin is available to tune up to 863.25 MHz.
Noise
Typical Max.
Gain
Min. Typical Max.
Low band : 5dB 9dB All channels : 38dB 44dB 52dB
Mid band : 5dB 9dB
Gain Taper (of f- air channels) : -
-
8dB
High band : 6dB 9dB
Channel Coverage UV1336:
BAND
CHANNELS FREQUENCY
RANGE (MHz)
Low Band 2 to D 55.25 to 139.25
Mid Band E to PP 145.25 to 391.25
High Band QQ to 69 397.25 to 801.25
Noise is typically 6dB for all channels. Gain is minimum 38dB and maximum 50dB for all channels.
4. VIDEO SWITCH TEA6415C
In case of three or more external sources are used, the video switch IC TEA6415C is used. The main function of
this device is to switch 8 video-input sources on the 6 outputs.
Each output can be switched on only one of each input. On each input an alignment of the lowest level of the
signal is made (bottom of sync. top for CVBS or black level for RGB signals).
Each nominal gain between any input and output is 6.5dB.For D2MAC or Chroma signal the alignment is
switched off by forcing, with an external resistor bridge, 5VDC on the input. Each input can be used as a normal
input or as a MAC or Chroma input (with external Resistor Bridge). All the switching possibilities are changed
through the BUS.
Driving 75ohm load needs an external resistor.
It is possible to have the same input connected to several outputs.
5. MULTI STANDARD SOUND PROCESSOR
The MSP 34x1G family of single-chip Multistandard Sound Processors covers the sound
processing of all analog TV-Standards worldwide, as well as the NICAM digital sound
standards. The full TV sound processing, starting with analog sound IF signal-in, down to pro-
cessed analog AF-out, is performed on a single chip. signal conforming to the standard by
the Broadcast Television Systems Committee (BTSC).
The DBX noise reduction, or alternatively, MICRONAS Noise Reduction (MNR) is performed
alignment free.
Other processed standards are the Japanese FM-FM multiplex standard (EIA-J) and the FM
Stereo Radio standard.
6. SOUND OUTPUT STAGE WITH TDA 7265
TDA7265 is a class AB dual Audio power amplifier assembled in the multiwatt package.
Mute stand-by function of the audio amplifier can be described as the following; the pin 5
(MUTE/STAND-BY) controls the amplifier status by two different thresholds, referred to +Vs. When
Vpin (5) higher than (+Vs - 2.5V) the amplifier is in Stand-by mode and the final stage generators are
off. When Vpin (5) is between (+Vs – 2.5V) and (+Vs – 6V) the final stage current generators are
switched on and the amplifier is in mute mode. When the Vpin (5) is lower than +Vs – 6V the amplifier
is play mode.