HITACHI C28WF540N
Service Manual

VIDEO PATH In this chassis the TDA 8885 video-processor (IC200) is used. The filtered IF signals are processed and sent as CVBS signal to the video switch IC (IC201). In IC201, according to the software and user control, the output CVBS signal is selected whether from the tuner, SCARTS, BAV, BAV or SVHS (or if exists DVD, DVB or else). The video IF signals from the SAW filters are processed in the video-processor, then sent as IF video output from pin 16. This output is again processed in the processor as CVBS signal from pin 24. The switched CVBS signal from IC201 is then processed as an input to pin 29. Then from pins 31/32/33 RGB signals are sent to the CRT baseboard as outputs. If there is an SVHS source the input signals from back or front SVHS jacks are input to pins 20/21 as chroma and luma respectively. If the TV is with comb-filter, both the CVBS and SVHS signals are filtered in the comb-filter IC (IC203). Then the outputs from IC203 are sent to video-processor. SOUND PATH The sound IF inputs (pins 8/9) are processed and sent as QSS output from pin 11 of IC200 to pin 58 of audio-processor IC700 as input. The sources other then IF are direct inputs to IC700. (SCARTS, FAV, BAV; pins 52/53/49/50/46/4743/44) These sound signals are processed and sent as outputs to audio amplifier IC701 (When Dolby Pro-logic or sub-woofer there are two audio-amplifiers.) or direct outputs from SCARTS, BAV, LINE OUT, HEADPHONE or else. If there are much more peripherals to give audio input, IC706 is used as a audio switch IC. In IC701, the main right and left audio signals are amplified and then given to the speakers. If the mute signal from the micro-controller comes, the amplifier is muted with hardware, the sound processor with software as well. R.G.B The R.G.B signals from pins 7,11 and 15 of the SCART connectors (PL207) are fed to the R.G.B input pins (41,42,43) of IC200. R.G.B operation can be enabled by either taking pin 16 of the SCART connector high, this high is fed to Pin 44 of IC200 or via the l²C bus the micro-controller sets IC200 to forced R.G.B mode in which the video processor generates its own fast blank signal. This puts the IC into external R.G.B mode and selects the inputs on pins 41,42 and 43, overriding the video input on pin 24/29. Note: when using R.G.B input the contrast, brightness and colour controls will still operate. DEFLECTION CIRCUIT All the sync signals and drive signals for the deflection part are sent from the videoprocessor. A fly-back pulse is taken from pin1 of the FBT. The east-west (EW) signal from pin 62 of IC200 feeds the EW circuitry and Q604, so the horizontal deflection is enlarged and arranged according to the tube size. Sand (castle) signal from pin57 of IC200 is used for vertical and horizontal synchronisation. The horizontal level is driven by the horizontal-drive-out signal from pin 56 to Q600, through the TR600 horizontal transformer and finally the horizontal transistor Q602 is driven. FBT (TR601) is driven with the B+ supply voltage from the SMPS pin20. The vertical stage is processed by the vertical-deflection IC (IC600). The inverted and non-

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