Sanyo AVM-1901S Schematic

AS

FILE NO.

SERVICE MANUAL Remote Control Color

Television

AVM-1901S (U.S.A.)

(CANADA)

ORIGINAL VERSION

Chassis No. G6V-1901S0

NOTE: Match the Chassis No. on

the unit’s back cover with
the Chassis No. in the
Service Manual.

If the Original Version
Service Manual Chassis
No. does not match the
unit’s, additional Service

Literature is required. You
must refer to “Notices” to the
Original Service Manual
prior to servicing the unit.

Contents

Safety Instructions. . . . . . . . . . . . . . . . . . . . . . . 2

Service Adjustments. . . . . . . . . . . . . . . . . . . 3 - 7

Purity and Convergence Adjustments . . . . . 8 - 9

Service Hints . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Mechanical Disassemblies. . . . . . . . . . . . . . . . 11

Chassis Electrical Parts List. . . . . . . . . . . 12 - 17

Cabinet Parts List . . . . . . . . . . . . . . . . . . . . . . 18

Component and Test Point Locations. . . . 19 - 21

Schematic Diagrams . . . . . . . . . . . . . . . . 25 - 32

Block Diagram . . . . . . . . . . . . . . . . . . . . . 26 - 27

Voltage Charts . . . . . . . . . . . . . . . . . . . . . 26 - 27

Waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Specifications

Power Rating . . . . . . . . . . . . . . . . . . . . . . 120V, 60Hz

68W (Avg), 1.4A(Max)

Antenna Input Impedance . . . . . . . . . . . . . . . . . . 75Ω

UHF/VHF/CATV

Receiving Channel. . . . . . . . . . . . . . . . . 2 - 13 (VHF),

14 - 69 (UHF),

01, 14-94, 95-125 (CATV)

Remote Ready . . . . . . . . . . . 23 Key Remote Control

Sound Output . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 W

Intermediate Frequency

Picture IF Carrier . . . . . . . . . . . . . . . . . . 45.75MHz

Sound IF Carrier. . . . . . . . . . . . . . . . . . . 41.25MHz

Color Sub Carrier . . . . . . . . . . . . . . . . . . 42.17MHz

Picture Tube . . . . . . . . . . . A48AAB37X/A48AGD12X

Semiconductors

Integrated Circuits. . . . . . . . . . . . . . . . . . . . . . . . . 7

Transistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Except within Tuner and RC Pre-Amp.

Cabinet Dimensions

Width. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 488mm

Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452mm

Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467mm

REFERENCE No.

SM5110190

AVM-1901S, G6VMM, PRODUCT CODE 111340691

A

S

— 2 —

SAFETY PRECAUTIONS

WARNING: The chassis of this receiver has a floating ground
with the potential of one half the AC line voltage in respect to
earth ground. Service should not be attempted by anyone not
familiar with the precautions necessary when working on this
type of equipment.
The following precautions must be observed:

1. An isolation transformer must be connected in the power line
between the receiver and the AC line before any service is
performed on the receiver.

2. Comply with all caution and safety-related notes provided on
the side of the cabinet, inside the cabinet, on the chassis, and
the picture tube.

3. When replacing a chassis in the cabinet, always be certain
that all the protective devices are installed properly, such as
control knobs, adjustment covers, shields and barriers.

DO NOT OPERATE THIS TELEVISION RECEIVER
WITHOUT THE PROTECTIVE SHIELD IN POSITION AND
PROPERLY SECURED.

4. Before replacing the back cover of the set, thoroughly inspect
the inside of the cabinet to see that no stray parts or tools
have been left inside.
Before returning any television to the customer, the
service technician must perform the following safety checks
to be sure that the unit is completely safe to operate without
danger of electrical shock.

ANTENNA COLD CHECK

Remove AC plug from the 120 VAC outlet and place a jumper
across the two blades. Connect one lead of an ohmmeter to the
jumpered AC plug, and touch the other lead to each exposed
antenna terminal (UHF and VHF antenna terminals). The resis­tance must measure between 1M ohm and 5.2M ohm. Any
resistance value below or above this range indicates an abnor­mality which requires corrective action.

LEAKAGE CURRENT CHECK

Plug the AC line cord directly into a 120 VAC outlet. (Do not use
an isolation transformer for this check.) Use an AC voltmeter,
that has 5000 ohms per volt or more sensitivity. Connect a 1500
ohm 10 watt resistor, paralleled by a 0.15 µF 150 VAC capacitor,
between a known good earth ground (water pipe, conduit, etc.)
and all exposed metal parts of the cabinet (antennas, handle
bracket, metal cabinet, screw heads, metal overlays, control
shafts, etc.). Measure the AC voltage across the 1500 ohm
resistor. The AC voltage should not exceed 750 mV. A reading
exceeding 750 mV indicates that a dangerous potential exists.
The fault must be located and corrected. Repeat the above test
with the receiver power plug reversed.

NEVER RETURN A RECEIVER TO THE CUSTOMER
WITHOUT TAKING THE NECESSARY CORRECTIVE
ACTION.

X-RADIATION PRECAUTION

The primary source of X-RADIATION in solid-state receivers is the
picture tube. The picture tube is specially constructed to limit X-Ray
emission. For continued X-RADIATION protection, the replacement
tube must be the same type as the original (including the suffix let­ter in the part numbers). Excessive high voltage may produce
potentially hazardous X-RADIATION. To avoid such hazards, the
high voltage must be maintained within specific limits. Refer to the X­RADIATION WARNING NOTE on the CHASSIS SCHEMATIC in
this service manual for specific high voltage limits. If the high volt­age exceeds specified limits, check the components specified on
the chassis schematic diagram and take the necessary corrective
action. Carefully follow the instructions for the +B Voltage Check
and the High Voltage Check to maintain the high voltage within the
specified limits.

HIGH VOLTAGE HOLD-DOWN TEST

To prevent X-RADIATION from the picture tube due to excessive
high voltage, a HOLD-DOWN circuit is provided in the high volt­age circuit. Every time the receiver is serviced, the high voltage
HOLD-DOWN circuit must be tested for proper operation. Refer
to the HIGH VOLTAGE HOLD-DOWN TEST in service adjust­ments.

PRODUCT SAFETY NOTICE

When replacing components in a receiver, always keep in mind
the necessary product safety precautions. Pay special attention
to the replacement of components marked with a star (★) in the
parts list and in the schematic diagrams. To ensure safe product
operation, it is necessary to replace those components with the
exact same PA RTS.

SAFETY INSTRUCTIONS



READING SHOULD NOT EXCEED 750 mV.

AC VOLTMETER

(5000 ohms per volt or more sensitivity)

TELEVISION

RECEIVER

Good earth ground
such as a water pipe,
conduit, etc.

AC OUTLET

1500 ohm

10 watt

0.15 µF 150V AC

To be touched to all of exposed metal parts.
Voltmeter Hook-up for Leakage Current Check.

GENERAL

This set has an On-screen Service Menu system included in the CPU that allows remote operation for most of the service adjustments.

ON-SCREEN SERVICE MENU SYSTEM

1. Enter the Service Menu:

• While pressing the MENU key, reconnect the AC power cord. The Service Menu Display will now appear. (See Figure 1 below.)

2. Service Adjustments:

• Press the ▲or ▼ key to select the desired service menu you want to adjust. (See page 4 for On-screen Service Menu.)

• Use the + or – key to adjust the data.

3. Exit from the Service Menu:

• Press the MENU key to turn off the Service Menu display.

SERVICE ADJUSTMENTS

— 3 —

IC802 (EEPROM) REPLACEMENT

When IC802 (EEPROM) is replaced, IC801 (CPU) will automatically write the initial reference data into IC802 for basic TV opera­tion. However, the bus data should be checked and some bus data should be set up before attempting the service adjustments.
(See pages 4 – 5 for detailed information.)

INITIAL BUS DATA SETUP

Note: When IC802 (EEPROM) is replaced, the Service Menu No. 007 VLN (V Linearity), No. 010 VSC (V S-Correction), No. 021 SBI

(Sub-Bias), No. 023 POS (Pre/Over-Shoot), No. 028 PRE (Pre-Shoot Width), No. 037 AF (AutoFlesh), No. 041 RYA (R-Y/B-Y
Angle) and No. 055 STI (Sub-Tint) should be set up for proper TV operation before attempting the service adjustments.

1. Disconnect the AC power cord (AC 120V line).

2. While pressing the MENU key, reconnect the AC power cord. The Service Menu display will now appear.

3. Select No. 007 VLN (V Linearity) with ▲ or ▼ key. Adjust the data with + or – key for 16.

4. Select No. 010 VSC (V S-Correction) with ▲ or ▼ key. Adjust the data with + or – key for 7.

5. Select No. 021 SBI (Sub-Bias) with ▲ or ▼ key. Adjust the data with + or – key for 60.

6. Select No. 023 POS (Pre/Over-Shoot) with ▲ or ▼ key. Adjust the data with + or – key for 1.

7. Select No. 028 PRE (Pre-Shoot Width) with ▲ or ▼ key. Adjust the data with + or – key for 3.

8. Select No. 037 AF (AutoFlesh) with ▲ or ▼ key. Adjust the data with + or – key for 1.

9. Select No. 041 RYA (R-Y/B-YAngle) with ▲ or ▼ key. Adjust the data with + or – key for 2.

10. Select No. 055 STI (Sub-Tint) with ▲ or ▼ key. Adjust the data with + or – key for 18.

11. Press the MENU key to turn off the Service Menu display.

No. Data
XXX XXX XXX XXXXXXXX

DECIMAL DATA
(ZERO SUPPRESSED)

Figure 1. Service Menu Display

No. 001-046, 053-057, 59, 63, 74-146

TITLE

BINARY DATA
(8 bit)

No. Data

72 DRV R XXX B XXX

No. 072

TITLE

OR

DECIMAL DATA
(ZERO SUPPRESSED)

DECIMAL DATA
(ZERO SUPPRESSED)

— 4 —

Table 1. ON-SCREEN SERVICE MENU

When IC802 (EEPROM) is replaced, check the bus data to confirm they are the same as below. The shaded menu should be checked
and be set up or readjusted according to the procedures described in the following pages. Initial Setup Data marked with an * should
be changed from Initial Reference Data. (See page 3 for Initial Bus Data Setup.)

No. TITLE

INITIAL REFERENCE INITIAL SETUP

RANGE OF DATA FUNCTION

DATA DATA

001 HFR 30 30 0~63 Align Horizontal Frequency
002 AFC 0 0 0, 1 Select Horizontal First Loop Gain & H-Sync Gating On/Off
003 HP 13 13 0~31 Align Sync to Flyback Phase (Horizontal Phase)
004 VS 50 50 0~127 Align Vertical Amplitude (Vertical Size)
005 VPO 5 5 0~63 Align Vertical DC Bias (Vertical Position)
006 VSP 0 0 0, 1 Select Vertical Sync Separation Sensitivity
007 VLN 19 16* 0~31 Align Vertical Linearity
008 CRS 0 0 0~3 Service Test Mode (Normal/Black/White/Cross)
009 GRY 1 1 0, 1 OSD Gray Tone Enable
010 VSC 8 7* 0~31 Align Vertical S-Correction
011 HBR 3 3 0~7 H-Blanking Control for Right Side Edge on Screen
012 HBL 4 4 0~7 H-Blanking Control for Left Side Edge on Screen
013 CDM 0 0 0, 1 Select Count Down Mode
014 VC 7 7 0~7 Align Vertical Size Compensation
015 RB 0 0 0~255 Align Red OUT DC Level (Red Bias)
016 GB 0 0 0~255 Align Green OUT DC Level (Green Bias)
017 BB 0 0 0~255 Align Blue OUT DC Level (Blue Bias)
018 RD 64 64 0~127 Align Red OUT AC Level (Red Drive)
019 GD 8 8 0~15 Align Green OUT AC Level (Green Drive)
020 BD 64 64 0~127 Align Blue OUT AC Level (Blue Drive)
021 SBI 64 60* 0~127 Align Common RGB DC Level (Sub-Bias)
022 OSD 2 2 0~3 Align OSD AC Level
023 POS 0 1* 0, 1 Select Control for Pre/Over-Shoot Adjustment
024 FLS 1 1 0~7 Select Y/C Filter Mode
025 CKO 3 3 0~7 Select Color Killer Operational Point
026 GYA 0 0 0, 1 Select G-Y Angle
027 CRG 2 2 0~3 Select Coring Gain (w/Defeat)
028 PRE 1 3* 0~3 Select Pre-Shoot Width
029 WP 1 1 0~3 Select White Peak Limitter Operating Point
030 FSW 0 0 0, 1 Enable RGB Blanking or FBP
031 VBL 0 0 0, 1 Select Vertical Blanking Period
032 BSG 1 1 0~3 Select Black Stretch Gain
033 BSS 1 1 0~3 Select Black Stretch Start Point (w/Defeat)
034 DCR 1 1 0~3 Select Luma DC Restoration
035 YGM 1 1 0~3 Select Y Gamma Start Point
036 CBP 0 0 0, 1 Select Chroma BPF Bypass
037 AF 0 1* 0, 1 Enable AutoFlesh Function
038 BAT 4 4 0~7 Align Brightness ABL Threshold
039 MSD 0 0 0, 1 Disable Brightness Mid Stop
040 ABL 0 0 0, 1 Disable Brightness ABL
041 RYA 4 2* 0~15 R-Y/B-YAngle
042 RAD 15 15 0~63 Align RF AGC Threshold (RF-AGC Delay)
043 IAS 0 0 0, 1 Disable IF and RF AGC (IF AGC Switch)
044 FMM 0 0 0, 1 Disable FM Outputs (FM Mute)
045 FL 15 15 0~31 Align WBA Output Level (FM Level)
046 VL 4 4 0~7 Align IF Video Level
053 SB 32 32 0~63 Align Sub-Brightness
054 SCO 10 10 0~31 Align Sub-Color
055 STI 22 18* 0~31 Align Sub-Tint
056 SSH 18 18 0~15 Align Sub-Sharpness
057 OPT 0 0 0~255 Option (Program Codes) (See Note 1 page 5.)
059 HR 13 13 0~31 Align OSD H-Position
063 SBO 5 5 0~255 Sub-Bright Offset

072 DRV

0~127 Red Drive Adjustment (See Note 2 page 5.)
0~127 Blue Drive Adjustment (See Note 2 page 5.)

– 0 0 0~255 Red Bias Adjustment (See Note 3 page 5.)

073 – 0 0 0~255 Green Bias Adjustment (See Note 3 page 5.)

– 0 0 0~255 Blue Bias Adjustment (See Note 3 page 5.)

074 R00 0 0 0~255 N/A

↓↓ ↓ ↓ ↓ ↓

146 R48 0 0 0~255 N/A

SERVICE ADJUSTMENTS (Continued)

— 5 —

PROGRAM CODES

The microprocessor used in this model is a multi-purpose type
and is used in several different models. To ensure proper
operation and the correct features for your particular model, the
Program Codes must be correct.

Note 1. Option Data 1 (No. 057 OPT) should be decimal 0
(00000000 binary). See page 3 INITIAL DATA SETUP for set

up procedure. If this program code is wrong the TV will not
operate properly.

Note 2. Red/Blue Drive Adjustments in Service Menu No.
072 DRV: Adjust Red and Blue Drive Levels alternately with 1,

3, 7, and 9 keys on the remote control. (See figure 2.) The Drive
Level adjustment data will be written in the Service Menu No.
018 and 020 automatically.

1

2

3

4 5 6

7 98

RB(–)

RB(+)

BB(–)

BB(+)

(N/A)

GB(–)

(N/A)

GB(+)

(N/A)

FOR RED BIAS ADJUSTMENT

FOR BLUE BIAS ADJUSTMENT

FOR GREEN BIAS ADJUSTMENT

Figure 2.

Figure 3.

1

2

3

4 5 6

7 98

RD(–)

RD(+)

BD(–)

BD(+)

(N/A)

(N/A)

(N/A)

(N/A)

(N/A)

FOR RED DRIVE ADJUSTMENT

FOR BLUE DRIVE ADJUSTMENT

BIT FUNCTION

DATA

01

0 TV/HOTEL TV HOTEL
1 NOT USED N/A
2 NOT USED N/A
3 NOT USED N/A
4 NOT USED N/A
5 NOT USED N/A
6 NOT USED N/A
7 NOT USED N/A

Note 3. Red/Green/Blue Bias Adjustments in Service Menu
No. 073: Adjust each Bias Level with 1, 3, 4, 6, 7, or 9 key on

the remote control. (See figure 3.) The Bias Level adjustment
data will be written in the Service Menu No. 015 ~ 017
automatically.

SERVICE ADJUSTMENTS (Continued)

— 6 —

ANTENNA CONNECTIONS

This receiver is designed for UHF/VHF reception. A 75 ohm
terminal is provided for UHF and VHF receptions. When
connecting a CATV antenna system, connect the 75 ohm
coaxial cable directly to the 75 ohm terminal. For 300 ohm VHF
antenna, use an adapter (not included with the TV set).

CIRCUIT PROTECTION

Fuse F601 (4A) is included in the AC line. This fuse must be
replaced with the proper fuse (see Parts List).

+B VOLTAGE CHECK

Connect Voltmeter + lead to TJ1 135V and – lead to ground
(TE7). Connect receiver to AC 120V line. Tune receiver to an
active channel. Set the picture controls to the Auto levels.
Voltage must measure between +133.0V and 136.1V. If the
voltage is out of this range, the power circuit must be checked.
No +B adjustment is provided on this chassis.

HORIZONT AL CENTERING ADJUSTMENT

1. Tune receiver to an active channel.

2. Check that picture is in the horizontal center of TV screen.
If picture is not centered horizontally, perform steps 3 ~ 6.

3.Turn off the receiver and disconnect the AC power cord
(120V AC line).

4. While pressing the MENU key, reconnect the AC power cord.
The Service Menu display will now appear.

5. Select No. 003 HP (Horizontal Phase) with ▲ or ▼ key.

6. Adjust the data with + or – key for proper horizontal center.
To turn off the Service Menu display, press the MENU key.

VERTICAL SIZE ADJUSTMENT

1. Tune receiver to an active channel.

2. Check the vertical size of the picture. If the vertical size is too
large or small, perform steps 3 ~ 6.

3.Turn off the receiver and disconnect the AC power cord
(120V AC line).

4. While pressing the MENU key, reconnect the AC power cord.
The Service Menu display will now appear.

5. Select No. 004 VS (Vertical Size) with ▲ or ▼ key.

6. Adjust the data with + or – key for full scan. To turn off the
Service Menu display, press the MENU key.

VERTICAL CENTERING ADJUSTMENT

1. Tune receiver to an active channel.

2. Che ck that picture is in the vertical center of TV screen. If pic­ture center is too low, replace resistor R513 (2.2K ohm, 1/2W)
with 470 ohm, 1W resistor. If picture center is too high, connect
resistor R512 (470 ohm, 1W).

GRA YSCALE ADJUSTMENT

1. Set the picture controls to the Auto levels.

2. Turn off the receiver and disconnect the AC power cord
(120V AC line).

3. While pressing the MENU key, reconnect the AC power
cord. The Service Menu display will now appear.

4. Select No. 015 RB (Red Bias), No. 016 GB (Green Bias),
and No. 017 BB (Blue Bias) with ▲ or ▼ key and set each
data to 0 with + or – key.

5. Select No. 018 RD (Red Drive) and No. 020 BD (Blue Drive)
with ▲or ▼ key and set each data to 64 with + or – key .

6. Set No. 019 GD (Green Drive) data to 8, No. 053 SB (Sub­Brightness) data to 32, No. 054 SCO (Sub-Color) data to
10, No. 055 STI (Sub-Tint) to 18 and No. 056 SSH (Sub­Sharpness) data to 18 with ▲ or ▼, and + or – keys.

7. T urn Screen Control (T402) to minimum (fully counterclock­wise).

8. Select the Service Menu No. 073 (Bias Adjustments) with ▲
or ▼ key.

9. Advance Screen Control (T402) clockwise to obtain just
visible one color line. If line does not appear, place this
control to maximum (fully clockwise).

10. Raise each Bias Level with 3, 6, and 9 keys to obtain just
visible white line. (See Figure 4 below.)

11. Select the Service Menu No. 072 DRV (Drive Adjustments)with
▲ or ▼ key.

12. Adjust Red and Blue Drive Levels alternately with 1, 3, 7, or
9 key to produce normal black and white picture in highlight
areas. (See figure 5 below.)

13. Check for proper grayscale at all brightness levels.
To turn off the Service Menu display, press the MENU key.

Note: If Grayscale Adjustment is made after picture tube

replacement, check Brightness Level Adjustment.

FOCUS ADJUSTMENT

Adjust focus control (T402) for well defined scanning lines.

CAUTION

FOR CONTINUED PROTECTION AGAINST A RISK
OF FIRE, REPLACE ONLY WITH THE SAME TYPE
4A, 125V FUSE.

ATTENTION : POUR MAINTENIR LA PROTECTION
CONTRE LES RISQUES D’ INCENDIE UTILISER UN
FUSIBLE DE RECHANGE DE MEME TYPE 4A, 125V

.

1

2

3

4 5 6

7 98

RB(–)

RB(+)

BB(–)

BB(+)

(N/A)

GB(–)

(N/A)

GB(+)

(N/A)

FOR RED BIAS ADJUSTMENT

FOR BLUE BIAS ADJUSTMENT

FOR GREEN BIAS ADJUSTMENT

Figure 4. Remote Control Number keys’ function in Service

Menu No. 073

1

2

3

4 5 6

7 98

RD(–)

RD(+)

BD(–)

BD(+)

(N/A)

(N/A)

(N/A)

(N/A)

(N/A)

Figure 5. Remote Control Number keys’ function in

Service Menu No. 072 DRV

FOR RED DRIVE ADJUSTMENT

FOR BLUE DRIVE ADJUSTMENT

4A 125V

— 7 —

VCO ADJUSTMENT

Note: VCO must be adjusted after IC101 (Signal Processor),

IC802 (EEPROM) or T151 (PLL VCO Coil) is replaced.

1. Connect digital voltmeter + lead to IC101 pin 58 (C153 (+))
on main board and – lead to main board ground.

2. T une receiver to an active channel. Set the picture controls
to Auto levels.

3. Confirm voltmeter reading of 3.6 ± 0.2 VDC.

4. If the voltage is out of this range, adjust PLL VCO Coil
(T151) for 3.6 ± 0.2 VDC.

5. Disconnect voltmeter from chassis.

RF-AGC ADJUSTMENT

1. Tune receiver to strongest VHF station in your area.

2. Set contrast and brightness controls for maximum.

3. Turn off the receiver and disconnect the AC power cord
(120V AC line).

4. While pressing the MENU key, reconnect the AC power
cord. The Service Menu display will now appear.

5. Select No. 042 RAD (RF-AGC Delay) with ▲ or ▼ key.

6. Adjust the data with + or – key in the direction which
causes snow to appear; then in the opposite direction until
the snow just disappears.

7. To turn off the Service Menu display, press the MENU key.

VIDEO LEVEL ADJUSTMENT

1. Connect a color-bar generator to the antenna terminal.
Switch the generator to a white field (100 IRE).

2. Set the picture controls to the Auto levels.

3. Turn off the receiver and disconnect the AC power cord
(120V AC line).

4. Connect oscilloscope + lead to terminal TP16 (C211(–)) on
main board and – lead to main board ground.

5. While pressing the MENU key, reconnect the AC power
cord. The Service Menu display will now appear.

6. Confirm voltage reading of 1.0 ± 0.1 Vp-p. If voltage is
within this range, Skip to Step 9. If voltage is out of this
range, go to step 7.

7. Select No. 046 VL(IF Video Level) with ▲ or ▼ key.

8. Adjust the data with + or – key for 1.0 ± 0.1 Vp-p at TP16.
To turn off the Service Menu display, press the MENU key.

9. Disconnect oscilloscope from chassis.

BRIGHTNESS LEVEL ADJUSTMENT

Note: Grayscale, RF-AGC, Video Level and High Voltage Check

must be adjusted before attempting Brightness Level
Adjustment.

1. Connect a color-bar generator to the antenna terminals.

2. Switch the generator to the crosshatch pattern.

3. Set the picture controls to the Auto levels.

4. Turn off the receiver and disconnect the AC power cord
(120V AC line).

5. Connect voltmeter (high impedance) + lead to terminal
TP51 and – lead to terminal TP50 on main board. Set
voltmeter for 1.5V ~ 3V range.

6. While pressing the MENU key, reconnect the AC power
cord. The Service Menu display will now appear.

7. Select No. 053 SB (Sub-Brightness) with ▲ or ▼ key.

8. Adjust the data with + or – key for 730 mVDC.

9. Press the MENU key to turn off the Service Menu display.

10. Check brightness level on every active channel, readjust
(repeat steps 5 ~ 9) if necessary.

Note: Do not set to excessive brightness level, otherwise the

contrast level will be suppressed.

HIGH VOLTAGE CHECK

Note: +B (+135V) Voltage Check and Grayscale Adjustment

must be completed before attempting High Voltage Check.

1. Connect high voltage voltmeter negative lead to ground,
and connect + lead to anode of picture tube.

2. Tune receiver to an active channel and confirm TV is
operating properly.

3. Eliminate the beam current by adjusting the contrast and
brightness controls to minimum.

4. Confirm high voltage is within 25.0 KV and 27.0 KV. If read­ing is not within range, check horizontal circuit.

No high-voltage adjustment is provided on this chassis.

HIGH VOLTAGE HOLD-DOWN TEST

Every time the receiver is serviced, the HIGH VOLTAGE
HOLD-DOWN circuit must be tested for proper operation by
following these steps:

1. Connect receiver to 120V AC line. Tune receiver to active
channel. Set the picture controls to the Auto levels.

2. Check that the voltage measured between TP7 and TE7
(ground side) is within 16.5 VDC to 21 VDC. If the voltage
is out of this range, the Hold-Down Circuit must be checked.

3. Connect a DC Voltage supply to TP7 and TE7 through a
100 ohm 1/4W resistor. Adjust the DC voltage to 23 VDC.
The receiver should shutdown, losing raster and sound.
Then the receiver should turn off automatically. This reac­tion indicates that the Hold-Down circuit is functioning
properly. If the receiver does not shutdown, a malfunction
is indicated and its cause must be found and corrected.

4. To obtain picture again, remove the DC Supply and wait a
few minutes. Now turn on the receiver.

FM LEVEL ADJUSTMENT

1. Select a channel with audio of 1 KHz 100% modulation. Set
the picture controls to the Auto levels.

2. Turn off the receiver and disconnect the AC power cord
(120V AC line).

3. Connect oscilloscope + lead to terminal TP21 (IC101 pin

75) on main board and – lead to main board ground.

4. While pressing the MENU key, reconnect the AC power
cord. The Service Menu display will now appear.

5. Confirm voltage reading of 1.5 ± 0.2 Vp-p. If voltage is
within this range, Skip to Step 8. If voltage is out of this
range, go to step 6.

6. Select No. 045 FL(FM Level) with ▲ or ▼ key.

7. Adjust the data with + or – key for 1.5 ± 0.2 Vp-p at TP21.
To turn off the Service Menu display, press the MENU key.

8. Disconnect oscilloscope from chassis.

— 8 —

PURITY AND CONVERGENCE ADJUSTMENTS

PURITY ADJUSTMENT

1. When replacing picture tube or deflection yoke, mount
deflection yoke and purity-convergence magnets assembly
properly. See Figure 1. Position the picture tube facing east
or west. Demagnetize the picture tube and receiver using
an external degaussing coil. Set receiver to Service Menu
No. 073 (no vertical sweep) while degaussing.

2. Place the yoke on tube neck fully against glass.

3. Connect a color bar generator to the antenna terminal.
Switch the generator to a white field. Move yoke backward
on the neck until a uniform white field is obtained.

4. Allow 30 minutes warm up on a blank white field (high
intensity grayscale).
Note: If white field cannot be obtained, check Grayscale

Adjustments on page 6.

5. Set the picture controls to the Auto levels. Select a green
raster, either with the signal generator or by adjusting the
bias controls. If a signal generator is used for this step, Skip
to Step 10. If the bias controls will be used, go to step 6.

6. Adjust Service Menu No. 015 RB (R-Bias), No. 016 GB (G­Bias), and No. 017 BB (B-Bias) data to 0 each.

7. Select Service Menu No. 073 (no vertical sweep).

8. Adjust the screen control counterclockwise until the
horizontal scan lines is no longer visible.

9. Select Service Menu No. 016 GB (G-Bias) and raise the
data to produce green raster. If retrace lines appear,
reduce screen control slightly.

10. Pull yoke back on the tube neck to obtain three-color raster
(blue, green and red).

11. Adjust the angle between the two purity magnet tabs to
center the vertical green belt in the picture tube. Do not
rotate tabs. See Figure 3.

12. Slowly slide the deflection yoke forward until a uniform
green screen is obtained.

13. Check the purity of the red and blue screens for uniformity.
Turn off other colors to check (use bias controls) or use
generator. If necessary, readjust the yoke position until all
screens are pure.

14. If bias controls and screen control were used to set purity,
reset Grayscale and Brightness Level. Refer to Grayscale
Adjustment on page 6 and Brightness Level Adjustment on
page 7.

15. Confirm that the yoke is not tilted. Tighten the yoke
mounting screw. Adjust convergence next.

CAUTION: Purity and Convergence adjustments have been made at the factory. Readjustments should be made
only after the picture tube or deflection yoke is replaced. Follow the steps below for the necessary readjustments.

Figure 1. Deflection Yoke Movement

Figure 2. Purity and Convergence Magnets

Figure 3. Adjusting Magnet

RUBBER
WEDGE

FOUR-POLE
MAGNET TABS

1

2

ANGLE
OF TABS

PURITY
MAGNET
TABS

DEFLECTION YOKE

SIX-POLE
MAGNET TABS

4

3

DEFLECTION YOKE
MOUNTING SCREW

ANGLE OF MAGNET TABS

MAGNET TABS