Zenith H19F34DT Series Service Manual

Also see for H19F34DT Series: Installation and operating guide, warranty

SR25-3828VD0171B 3-5 CL - SERVICINGSERVICE ADJUSTMENTS (continued)SWITCHING PROCESSVideo switching is done between the CV inputs and theY/C inputs. There are three CV signals to consider:CAMPORT VIDEO enters at pin 7 of IC2901.REAR VIDEO enters at pin 5 of IC2901.IF Video enters at TV pin 12 of IC2901.These signals exit from VOUT1 (pin 11) to be processedand returned to the switch as Y/C signals (Y-COMB andIC2902).The second part of the switching is between:Y/C COMB signals enter at pins 10 and 7 of IC2902 andY/C EXT signals entering at pins 12 & 5 of IC2902.The selected Y/C signals exit from pins 11 & 8 to besent to the video processor as main signals.Close caption is achieved by taking a signal from theYSW-OUT pin (31) of the video processor.SENSING AND PRIORITIESCL-Series 34 & 39 models do not have a source menu.Software sensing the inputs based on their prioritiesdoes switching between sources.The camport input always has first priority, it is senseddirectly through the microprocessor. The S-Video inputhas the second level. The Y/C connector does the S-Video sensing. The third level corresponds to rear videoand antenna signal (RF), they would be selected byremote control.VIDEO PROCESSING & SWITCHING WITH Y/C INPUT63642627141516ICM2200M61250FP58VIDEO OUT“CAMPORT” JK PK inputsV R L“REAR” JK PK inputsC-INY-INYSW-OUTFBLNKROSDGOSDBOSD3124252627AudioTrapY-Main for MICROMicroProcessorIC29028115712105IC2400COMB FILTERTRAP3.58BPF3.58Y EXITC EXITYC SENSE LINEY/C INSCLSDAROUTGOUTBOUTPIFINVideo Sense LineC-MAINY-MAINMain BoardVR LTunerIFSAW Filter2ToVideoOutputBoardFSC 29TC90 A45P7384198IC2901