Panasonic CT-27D10B Service Manual

Also see for CT27D10DB - 27" COLOR TV: User guide

Panasonic CT-27D10B Service Manual Manual pdf 24 page image

- 24 -Service Adjustments (Electronic Controls)Sub-BrightnessServiceman DAC Adjustment (B2)Adjustment of this control is important for setting properoperation of customer brightness and picture controls.This adjustment must be made after Sub-Contrast orColor Temperature adjustments are made. Do notadjust SCREEN after the Sub-Brightness is set.Preparation:Apply a color bar signal wit 100 IRE white and 7.5IRE black. (Switch Color to “OFF” on the signalgenerator.) Operate the Receiver for a minimum of10 minutes prior to performing this adjustment.Procedure:In the Serviceman Mode for making electronicadjustments, select the DAC adjustment (B2) andadjust until the black starts to look gray. Thendecrease the level to the point where gray turnsto black.Note: You may set the accurate value following thePreparation steps and the Procedure step No.2 of the Sub-Contrast adjustment describedbelow.Sub-ContrastServiceman DAC Adjustment (B3)This adjustment is factory set. Do not adjust unlessrepairs are made to associated circuit, the CRT Boardor when the CRT is replaced.Preparation:1. Apply a color bar signal pattern with 87.5%modulation, 70% saturated color bar with a 100IRE white and 7.5 black.Note: The pattern used in this procedure is an EIA colorbar pattern with 87.5% modulation with 100 IREwhite and 7.5 black. Correlate the information in thisprocedure to the pattern used if another signalis used.2. Preset the following controls:• Brightness. . . . . . . . Center.• Color . . . . . . . . . . . . Min.• Picture . . . . . . . . . . Max.• Sharpness . . . . . . . Center.3. Connect the oscilloscope to TP47R. Set the scopetime base to 20μs (horizontal).4. Connect a jumper from TPD2 to ground ( )..Procedure:1. In the Serviceman Mode, select DAC Sub-Brightness Adjustment (B2) and adjust for 1.5-1.9Vp-p between blanking and 7.5 IRE level. (Seevideo waveforms detail, Fig. 19)2. In the Serviceman Mode for electronicadjustments, select DAC Sub-Contrast Adjustment(B3) and adjust for 2.0Vp-p ±0.1V white level toblack level on video waveform (see videowaveforms detail, Fig. 19).3. Remove the jumper (Preparation step 4).Tint/Color AdjustmentServiceman DAC Adjustment (B1) (B0)Preparation:1. Apply a rainbow color bar signal.2. Preset the following controls:• Brightness . . . . . . . Min.• Color . . . . . . . . . . . . Center.• Tint . . . . . . . . . . . . . Center.• Picture . . . . . . . . . . Max.• Sharpness . . . . . . . Min.3. Connect the oscilloscope to TP47B (A-Board).4. Connect a jumper from TPD2 to GND ( ).5. Change the value of DAC S3 from 1 to 0.Procedure:1. In the Serviceman Mode for making electronicadjustments, select DAC Sub-Tint Adjustment(B1). Adjust until the waveform measured is as theone shown in Fig. 20.2. Connect the oscilloscope to TP47G (A-Board).3. Select DAC Sub-Color Adjustment (B0) and adjustfor peak to peak amplitude to be 0.65Vp-p ±0.05Vfor 27” models as shown in Fig. 21.4. Remove the jumpers (Preparation steps 4 & 5).Figure 19. TP47G waveformWhiteYellowCyan GreenMagentaRedBlueBlackSYNCTIP1.5V - 1.9V p-p2.0Vp-p ±0.1VA to B = 1 unitAC1 2 3 104 5 6 7 8 9BB to C = 2 unitsFigure 20. TP47B waveformTP47B (A-Board)1 2 3 4 5 67 8 9 10Figure 21. TP47G waveformTP47G (A-Board)0.65Vp-p±0.05V