Device Specifications; Analogue Signal Processing (Front-End); Tuner (Td1716); Master If (Tda9898) - Philips 32PFL9432/98 Service Manual

Circuit Descriptions, Abbreviation List, and IC Data Sheets
9.6.1

Device specifications

Tuner (TD1716)

The tuner has the following specifications:
• Hybrid tuner with symmetrical IF output.
• Down conversion from RF to IF frequency (picture carrier
39.875 MHz at analogue reception, centre frequency
36.166 MHz at digital reception).
• AGC control signal is coming from master IF device
(TDA9898).
• Only 5 V external supply needed (internal DC-DC
conversion to 3.3 V).
• 4 MHz output is used by channel decoder (TDA10048) and
master IF device (TDA9898).
The application in this chassis is as follows:
2
• I C address C0.
• Broadband AGC, no IF section.
2
• I C communication buffered via MUX.
• Gain to obtain optimised Master IF input level; AGC control
is completely inside the tuner.
• Output level ca. 110 dBμV (for strong input signal).
Repair tip: after replacement of the tuner, the option code
should be checked, even when the set appears to function
correctly! Refer also to chapter 5 "Service Modes, Error Codes,
and Fault Finding".

Master IF (TDA9898)

• Down conversion from IF to low-IF frequency.
• Down conversion from IF to SIF.
• CVBS output.
The application in this chassis is as follows:
2
• I C address 0x86.
• Down conversion from IF to low-IF frequency (5.166 MHz
centre frequency).
• Advanced filtering (for further rejection of adjacent
channels).
• Gain to obtain optimised channel decoder level. Control
signal is coming from channel decoder.
SAW filter
X6766D or X6872D
• Analogue sound for BG, I, DK, L, L'.
• DVB-T (digital reception sound and video).
For digital reception, the application in this chassis is as
follows:
• Rejection of adjacent channels.
• Switching is done by Master IF (3 inputs).
• One SAW covering both 7 and 8 MHz channels.
X6768D
• Analogue video for BG, I, DK, L, L'.
Channel decoder (TDA10048)
The channel decoder has the following specifications:
2
• I C address 0x10.
• Decoding from low-IF to MPEG transport stream.
• During decoding: de-modulation, de-interleaving and error
correction.
• External clock buffer required.
• No start-up requirements.
• AGC monitor.
9.6.2

Analogue signal processing (front-end)

Refer to figure "PAL/SECAM video broadcast reception block
diagram" and "PAL/SECAM audio broadcast reception block
diagram" for details of analogue signal processing.
Q528.1A LA 9. EN 173