SHARP 20A2
Service Manual

CONVERGENCE ADJUSTMENT
NO. Adjustment part 1 CONVERGENC ADJ. (To be done after the purity adjustment.) Adjusting procedure and conditions 1. Receive the "Crosshatch Pattern" signal. 2. Using the remote controller, call NORMAL mode. Static convergence 1. Turn the 4-pole magnet to a proper opening angle in order to superpose the blue and red colours. 2. Turn the 6-pole magnet to a proper opening angle in order to superpose the green colour over the blue and red colours. Dynamic convergence 1. Adjust the convergence on the fringes of the screen in the following steps. a) Fig. 5-1: Drive the wedge at point "a" and swing the deflection coil upward. b) Fig. 5-2: Drive the wedge at points "b" and "c" and swing the deflection coil downward. c) Fig. 5-3: Drive the "c" wedge deeper and swing the deflection coil rightward. d) Fig. 5-4: Drive the "b" wedge deeper and swing the deflection coil leftward. 2. Fix all the wedges on the CRT and apply glass tape over them. 3. Apply lacquer to the deflection yoke lock screw, magnet unit (purity, 4-pole, 6-pole magnets) and magnet unit lock screw. Finally received the Red-only and Blue-only signals to make sure there is no other colours on the screen.
About 100° Lacquer Wedge "b" Wedge "c" About 100°

CRT CUT-OFF, BACKGROUND AND SUB-CONTRAST ADJUSTMENT
NO. Adjustment part 1
B G R

Waveform and others
BGR

Adjusting procedure and conditions 1. Switch TV to VIDEO mode, BLUE BACK OFF with NO VIDEO signal. 2. Press R/C to set Picture Normal condition. 3. Connect the oscilloscope to Red OUT from IC801.(TP852) Range Sweep : 1 V/Div (DC) : 5 msec/Div
0

Waveform and others
3.0Vdc

CRT CUTOFF ADJUSTMENT (I2C BUS CONTROL)

Fig. 5-1
RGB R G B

1V

4. Adjust SCREEN VR, so that the tip of signal reach 3.0 +0.1 Vdc. 2 SUBBRIGHTNESS ADJUSMENT (I2C BUS CONTROL) 1. Call "SUB-BRI" in service mode. (Receive Crosshatch pattern with 5 black level windows) 2. Adjust the "SUB BRIGHT" bus data in order that the line 1, 2 and 3 have the same darkness wherelse line 4 is slightly brighter than line 1, 2 and 3 and finally line 5 will be the brighter than line 4.

Fig. 6

Fig. 5-2 RGB
B G R

12345

1, 2 and 3 are in same black level. Fig. 7 Refer to Page 7. * 7500°K X : 0.300 Y : 0.310 * 12,300°K X : 0.272 Y : 0.275

Fig. 5-3
R G B BGR

3

WHITE BALANCE SERVICE MODE ADJ. (I2C BUS CONTROL)

1. Receive the "Monoscope Pattern" signal. 2. Press R/C to set Picture NORMAL condition. 3. Connect the DC miliammeter between TP602 (-) and TP603 (+). 4. Check Beam current should be around 1,100 µA. 5. Set it to service mode and adjust the " WPG" (White Point-G), "WPB" (White Point-B) data to have a colour temperature of 12,300°K or 7500°K (white). * Note . 6. When changed back to non-service mode, adjust the Contrast & Brightness control to have a beam current of 200µA. If the colour temperature is not at 12,300°K or 7500°K go back to No. 1. Note: This adjustment must be done after warming up the unit for 30 minutes or longer with a beam current over 700µA). * ADJUST DRI-GC/GW, DR-BC/BW AS FOLLOWING DATA, AFTER FIHISHING DRI-GS AND DRI-BS. DRI-GC/GW DATA: "DRI-GS"-7 DATA DRI-RC:27 DRI-BW DATA: "DRI-BS" -5 DATA DRI-BC=DRI-BS

Fig. 5-4
Wedge "a"

(MINOLTA COLOUR ANALYZER CA-100) *Note: Above Data can be UP/ DOWN by Volume key.

9

Fig. 5-5
4-pole magnet 6-pole magnet CRT neck

4
Lacquer Purity magnet
20cm

Maximum beam check

Fig. 5-6

1. Receive the "Monoscope Pattern" signal. 2. Press R/C to set Picture NORMAL condition. 3. Connect the DC miliammeter between TP603 (+) and TP602 (�). (Full Scale: 3 mA Range) 4. Beam current must be within 1,100 ±100 µA.

20A1/2, 20AG1/2 21A1/2, 21AG1/2

9-1

9-2