electrotricks: 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.