JVC AV 20D303 – HOW TO ENTER SERVICE MODE – SCHEMATIC

JVC  AV-20D303 HOW TO ENTER THE SERVICE MODE, SERVICE MODE ADJUSTMENTS AND SCHEMATIC

When erecting the chassis, be careful so that there will be no contacting with other PW Board.
Before turning on power, make sure that the wire connector is properly connected.
When conducting a check with power supplied, be sure to confirm that the CRT EARTH WIRE (BRAIDED ASS’Y) is connected to the CRT SOCKET PW board.

CCIR(M)
NTSC-M
BTSC System (Multi-Channel Sound)

23-3/8”×18”×19-1/4” (592mm×456m m×487mm), 120V AC, 60Hz 87W

20” (51cm) Measured Diagonally
26.5kV±1kV (at zero beam current)

Speaker: 2“×3-1/2” (5×9cm) Oval type×2.  1.2W + 1.2W

REMOTE CONTROL UNIT [RM-C253]

How to enter the SERVICE MENU.
Press the SLEEP TIMER key and set the SLEEP TIMER for 0 MIN.
Then press the DISPLAY key and VIDEO STATUS key of the remote control unit at the same time to enter the SERVICE MENU screen.

SERVICE MENU screen selection
In SERVICE MENU, press the MENU▼/▲(CH-/+) key to select any of the SUB MENU items.
(The letters of the selected items are displayed in yellow.)

Enter the any setting ( adjustment ) mode
1.V/C (S), 2.DEF (D), 3.SOUND (A), 4.OTHERS (F), 5.PIP (P), 6.3L Y/C (LYC), 7.LOW LIGHT, 8.HIGH LIGHT, 9.RF AFC 10.VCO 11.I2C BUS and 12.SYSTEM (SYS) mode.

If select any of 1.V/C (S) / 2.DEF (D) / 3.SOUND (A) / 4.OTHERS (F) / 5.PIP (PIP) / 6.3L Y/C (LYC) / 7.LOW LIGHT / 8.HIGH LIGHT / 9.RF AFC / 10.VCO / 11.I2C BUS /12.SYSTEM (SYS) items, and the MENU / (VOL-/+) key is pressed from SERVICE MENU ( MAIN MENU ), the each screens will be displayed.

Then the settings or verifications can be performed.

Setting method
1) MENU ▼/▲ (CH-/+) key.
Select the SETTING ITEM.
2) MENU / (VOL-/+) key
Setting (adjust) the SETTING VALUE of the SETTING ITEM.
When the key is released the SETTING VALUE will be stored (memorized).
3) EXIT key
Returns to the previous screen,

Releasing SERVICE MENU
1) After returning to the SERVICE MENU upon completion of the setting (adjustment) work, press the EXIT key again.

★ The settings for LOW LIGHT and HIGH LIGHT are described in the WHITE BALANCE page of ADJUSTMENT.
★ The setting for MAIN VCO are described in the VCO page of ADJUSTMENT,

INITIAL SETTING VALUE OF SERVICE MENU

Adjustment of the SERVICE MENU is made on the basis of the initial setting values ; however, the new setting values which set the screen in its optimum condition may differ from the initial setting.

Do not change the initial Setting Values of the Setting (Adjustment) items not listed In “ADJUSTMENT”.

B1 POWER SUPPLY adjustment

1. Receive the black-and-white signal. (color off)
2. Connect the DC voltmeter to【B1】connector【1】pin (TP-91) and TP-E(#) (B1 connector【3】pin).
3. Confirm that the voltage is DC134V±2V

ADJUSTMENT OF VCO

It must not adjust without signal.
1. Select a receivable broadcast .
2. Push the MENU▼/▲(CH-/+) key, and select the 10.VCO mode from the SERVICE MENU.
3. Push the MENU / (VOL-/+) key, and select MAIN.
4. Confirm that the color change from ｢HIGH LEVEL｣ to ｢LOW LEVEL｣ by CW TRANSF T111 at MAIN PWB, and check the ｢SYNC : YES｣.
5. Adjust until ｢REFFERENCE LEVEL｣ mark turns green.
And then confirm that the ｢SYNC : YES｣ again.

ADJUSTMENT OF RF AGC, ADJUSTMENT OF FOCUS & ADJUSTMENT OF DEFLECTION CIRCUIT

RF AGC

Receive a black and white signal (colour off).
2. Select S45 AGC ADJ of the V/C MODE.
3. Press the MUTING key and turn off color.
4. With the MENU (VOL-) key to get the noise in the screen picture (zero s ide of setting value).
5. Press the MENU (VOL+) key several times and step when noise disappears from the screen ( at that time, not to increase the value too much).
6. Change to other channels and make sure that there Is no irregularity.
7. Press the MUTING key and get color out.

Focus

1. Receive the cross-hatch signal.
2. While looking at the screen, adjust the FOCUS VR to the vertical and horizontal lines will be clear and in fine detail.
3. Make sure that the picture is in focus even when the screen gets darkened.

Deflection circuit

1. Receive the cross-hatch signal.
2. Select the D05 V PHASE of the DEF (D) mode, and it checks that the value of D05 V PHASE is 0.
3. Adjust the vertical screen size of the screen top to 92% with the D07 V SIZE and V CENTER SW S401

1. Receive the cross-hatch signal.
2. Select D03. H POSI from DEF (D) mode.
3. Adjust by H POSITION to be same size at both sides.

White balance adjustment

1. Receive the black and white signal ( color off ).
2. Select the [LOW LIGHT] MODE from the SERVICE MENU.
3. Set the initial setting value of “R CUTOFF”, “G CUTOFF” “B CUTOFF” and BRIGHT.
0. Display a single horizontal line by pressing the ① key of the remote control unit.
5. Turn the screen VR all the way to the left.
6. Turn the screen VR gradually to the right from the left until either one of the red, blue or green colors appears faintly.
7. Adjust the two colors which did not appear until the single horizontal line that is displayed becomes white using the ④ to ⑨ keys of the remote control unit.
8. Turn the screen VR until the single horizontal line is displayed faintly.
9. Press the ② key to cancel the single horizontal line mode.
10. Adjust the BRIGHT level to become the black component shines white slightly.
11. Confirm that whether the color ingredient of R,G,or B is visible to the black component, which shines white slightly
12. When the color ingredient can be seen, two colors other than a visible color are adjusted, and it is made to look white.
13. Return the value of BRIGHT to initial setting value.
●The ③ EXIT key is the cancel key for the WHIT E BALANCE.

Sub-color adjustment

Sub-tint adjustment

MTS circuit adjustment

Schematic

 

STR G5624-F8 – CXA2134AQ-X – TM8812CSANG3PF2 – TA1218AN – TC90A49P – M52342SP – AT24C04 – 20D303

ADJUSTMENT OF B1 POWER SUPPLY).
The high voltage applied to the picture tube must conform with that specified in Service manual. Excessive high voltage can cause an increase in X-Ray emission, arcing and possible component damage, therefore operation under excessive high voltage conditions should be kept to a minimum, or should be prevented. If severe arcing occurs, remove the AC power immediately and determine the cause by visual inspection (incorrect installation, cracked or melted high voltage harness, poor soldering, etc.). T o maintain the proper minimum level of soft X-Ray emission, components in the high voltage circuitry including the picture tube must be the exact replacements or alternatives approved by the manufacturer of the complete product.
Do not check high voltage by drawing an arc. Use a high voltage meter or a high voltage probe with a VTVM. Discharge the picture tube before attempting meter connection, by connecting a clip lead to the ground frame and connecting the other end of the lead through a 10kΩ 2W resistor to the anode button.
1. Receive the black-and-white signal. (Color off)
2. Connect the DC voltmeter to[B1]connector [1] pin (TP-91) and TP-E(Ground) (B1 connector [3] pin).
3. Confirm that the voltage is DC134V±2V.
Circuit (Schematic) Diagram

How to enter the SERVICE MENU.
Press the SLEEP TIMER key and set the SLEEP TIMER for [0 MIN].
Then press the DISPLAY key and VIDEO STATUS key of the remote control unit at the same time to enter the SERVICE MENU screen.

SERVICE MENU screen selection
In SERVICE MENU, press the MENU ▼/▲(CH-/+) key to select any of the SUB MENU items.  (The letters of the selected items are displayed in yellow.)

Enter the any setting ( adjustment ) mode
1.V/C (S),

2.DEF (D),

3.SOUND (A),

4.OTHERS (F),

5.PIP (P),

6.3L Y/C (LYC),

7.LOW LIGHT,

8.HIGH LIGHT,

9.RF AFC

10.VCO

11.I2C BUS

12.SYSTEM (SYS) mode.

1) If select any of 1.V/C (S) / 2.DEF (D) / 3.SOUND (A) / 4.OT HERS (F) / 5.PIP (PIP) / 6.3L Y/C (LYC) / 7.LOW LIGHT / 8.HIGH LIGHT / 9.RF AFC / 10.VCO / 11.I2C BUS /12.SYSTEM (SYS) items, and the MENU / (VOL-/+) key is pressed from SERVICE MENU ( MAIN MENU ).

The settingsSetting method

1) MENU ▼/▲ (CH-/+) key. Select the SETTING ITEM.
2) MENU / (VOL-/+) key.  Setting (adjust) the SETTING VALUE of the SETTING ITEM.
When the key is released the SETTING VALUE will be stored (memorized).
3) EXIT key.  Returns to the previous screen.

Releasing the SERVICE MENU

1) After returning to the SERVICE MENU upon completion of the setting (adjustment) work, press the EXIT key again.

[1. Adjustment of the SERVICE MENU is made on the basis of the initial setting values ; however, the new setting values which set the screen in its optimum condition may differ from the initial setting.

2. Do no t change the initial Setting Values of the Setting (Adjustment) items not listed In “ADJUSTMENT”.]

BASIC OPERATION OF SERVICE MENU

In general, basic setting (adjustments) items or verification are performed in the SERVICE MENU.
(1) V/C (S) ･････････････････････ This set the setting values (adjustment values) of the VIDEO/CHROMA circuits.
(2) DEF (D) ････････････････････ This set the setting values (adjustment values) of the DEFLECTION circuit.
(3) SOUND (A) ･････････････････ This set the setting values (adjustment values) of the AUDIO circuit.
(4) OTHERS (F) ････････････････ This is used when the OTHERS MODE is verified. [Do not adjust]
(5) PIP (PIP) ･･･････････････････ This set the setting values(adjustment values) of the PICTURE-IN-PICTURE
(6) 3L Y/C (LCY) ････････････････This is used when the 3L Y/C MODE is verified.
(7) LOW LIGHT ･････････････････This sets the setting values (adjustment values) of the WHITE BALANCE circuit.
(8) HIGH LIGHT ････････････････ This sets the setting values (adjustment values) of the W HITE BALANCE circuit
(9) RF AFC ････････････････････ This is used when the RF AFC MODE is verified. [Do not adjust]
(10)VCO ･･･････････････････････ This is used when the IF VCO is adjusted.
(11)I 2C BUS ････････････････････ This is used when ON/OFF of the I2C BUS CTRL is set. [Fixed ON]
(12)SYSTEM (SYS) ･･････････････ This is used when the SYSTEM is verified.

 12.SYSTEM (SYS) do not adjust normally. [The adjustment should not be done without signal.]

MEMORY IC REPLACEMENT

The memory IC stores data for proper operation of the video and deflection circuits.  When replacing the memory IC, be sure to use an IC containing this (initial value) data.

Power off.  Switch off the power and disconnect the power cord from the outlet.
Replace the memory IC.  Be sure to use a memory IC written with the initial setting data.
Power on.  Connect the power cord to the outlet and switch on the power.

Confirm the system constant value.

How to enter the SYSTEM (SYS).
1) Press the SLEEP TIMER key and set SLEEP TIMER for [0 min].
2) Before disappear the display of SLEEP TIMER settings, simultaneously press the DISPLAY key and VIDEO STATUS key of the remote control unit.
3) The SERVICE MENU screen of Fig.1 is displayed.
4) While the SERVICE MENU is displayed, select the SYSTEM(SYS) item with MENU▼/▲ (CH-/+) keys, and the MENU / (VOL-/+) keys is pressed, the screen will be displayed.
5) Refer to the SYSTEM (SYSTEM CONSTANT) TABLE 1 and check the setting items. If the value is different, select the setting item with the MENU ▼/ ▲ (CH-/+) keys and adjust the setting with the MENU / (VOL-/+) keys. (The letters of the selected item are displayed in yellow.)
6) When adjustment has completed, the values store into memory IC automatically
7) Press the EXIT key twice to return the normal screen.