SEG CT7800II
Manual de Servicio

AK19 CHASSIS MANUAL ADJUSTMENTS PROCEDURE
In order to enter the service menu, first enter the installation menu and then press the digits 4, 7, 2 and 5 respectively. For ADJUST settings: Select Adjust using VorA button and press Oor<^| button to enter it. To select different adjust parameters, use V^A button. To change the selected parameter, use [> or <] button. WHITE BALANCE ADJUSTMENT: The following three parameters are used to make white balance adjustment. To do this, use a Colour Analyser. Using white point RED, white point GREEN and white point BLUE parameters, insert the + sign in the square which is in the middle of the screen. ADJUST 00 = White Point RED ADJUST 01 = White Point GREEN ADJUST 02 = White Point BLUE AGC ADJUSTMENT: In order to do AGC adjustment, enter a BOdBmV RF signal level from channel C-12. Connect a digital voltmeter to pin 1 of the tuner. Change the, AGC parameter until you see 3.70VDC on voltmeter display. Check that picture is normal at 90dBmV signal level. ADJUST 03 = AGC IF-PLL NEGATIVE ADJUSTMENT (Only with PLL tuner): Connect 38.9 MHz test pattern for PAL B/G, PAL-SECAM B/G, 39.5 MHz test pattern for PAL I or 45.75 MHz test pattern for PAL M/N, NTSC M model to Z401 SAW filter input terminals. Change the IF-PLL Negative parameter until you see IN, DOWN below. If you cannot catch IN, DOWN position this way, using a screwdriver rotate the VIF-COIL LT401 left or right until you see IN, DOWN. ADJUST 04 = IF-PLL Negative IF-PLL POSITIVE ADJUSTMENT (Only with PLL tuner): Connect 33.9 MHz test pattern for SECAM L' model to Z401 SAW filter input terminals. Change the IF-PLL Positive parameter until you see IN, DOWN below. If you cannot catch IN, DOWN position this way, using a screwdriver rotate the VIF-COIL LT401 left or right until you see IN, DOWN. ADJUST 05 = IF-PLL Positive LUMINANCE DELAY ADJUSTMENT (with only TDA 8844 video processor): ADJUST 06 = Y-Delay PAL Enter a PAL B/G colour and black-white bar test pattern via RF. Adjust Y-Delay PAL till the colour transients on the colour bar of the pattern become as sharper and colours between transients do not mix with each other as possible. Note: If the SAW filter is one of the G1965M, J1951M, J3950M, K2958M, K2962M, G3957M, K6256K, K6259K or M1963M, there is constant group delay distortion, so for an equal delay of the luminance and chrominance signal the delay must be set at a value of i60nS. This means the adjustment must be set to the maximum value. ADJUST 07 = Y-Delay SECAM Enter a SECAM B/G colour and black-white bar test pattern via RF. Adjust Y-Delay SECAM till the colour transients on the colour bar of the pattern become as sharper and colours between transients do not mix with each other as possible. Note: If the SAW filter is one of the G1965M, K2958M, K2962M, G3957M, K6256K or K6259K, there is constant group delay distortion, so (or an equal delay of the luminance and chrominance signal the delay must be set at a value of I60nS. This means the adjustment must be set to the maximum value. ADJUST 08 = Y-Delay NTSC Enter an NTSC colour and black-white bar test pattern via RF. Adjust Y-Delay NTSC till the colour transients on the colour bar of the pattern become as sharper and colours between transients do not mix with each other as possible. Note: If the SAW filter is M1963M, there is constant group delay distortion, so for an equal delay of the luminance and chrominance signal the delay must be set at a value of I60nS. This means the adjustment must be set to the maximum value. ADJUST 09 = Y-Delay Other In case of other colour systems, enter this system with colour and black-white bar test pattern via RF. Adjust Y-Delay Other till the colour transients on the colour bar of the pattern become as sharper and colours between transients do not mix with each other as possible. Normally for an equal delay of the luminance and chrominance signal the delay must be set at a value of I60nS. This means the adjustment must be set to the maximum value.

VERTICAL ZOOM ADJUSTMENT (only for 1100 picture tubes):
ADJUST 10 = Vertical Zoom Enter a PAL B/G circle test pattern via RF. Change vertical zoom till you see the upper and lower limit of the circle as close to the upper and lower limit of the picture tube as possible. VERTICAL SCROLL ADJUSTMENT (only for 110e picture tubes): ADJUST 11 = Vertical Scroll Enter a PAL B/G circle test pattern via RF. Change vertical scroll till you see the circle exactly in the middle of the screen. 4:3 HORIZONTAL SHIFT ADJUSTMENT: ADJUST 1 2 = 4 : 3 Horizontal Shift Enter a RED PURITY test pattern via RF.Change horizontal shift till the picture is horizontally centred. Check whether this adjustment is correct after completing Service Mode Adjustment.
4:3 VERTICAL SLOPE ADJUSTMENT:

ADJUST 1 3 = 4 : 3 Vertical Slope Enter a CROSS-HATCH B/G test pattern via RF. Change vertical slope till the size of squares on both the upper and lower part of test pattern become equal to the squares laying on the vertical centre of the test pattern. Check and readjust VERTICAL SLOPE item if the adjustment becomes improper after some other geometric adjustments are done.

20