GE 32GT720 Schematic

SAFETY PRECASAFETY PRECA

SAFETY PRECA

SAFETY PRECASAFETY PRECA

SERSER

VICE VICE

SER

SERSER

Only qualified service technicians who are familiar with safety checks and guidelines should perform service work. Before replacing parts, disconnect power source to protect electrostatically sensitive parts. Do not attempt to modify any circuit unless so recommended by the manufacturer. When servicing the receiver, use an isolation transformer between the line cord and power receptacle.

SERSER

SER

SERSER

Use EXTREME CAUTION when servicing the high voltage circuits. To discharge static high voltage, connect a 10K ohms resistor in series with a test lead between the receiver ground and CRT anode lead. DO NOT lift the CRT by the neck. Always wear shatterproof goggles when handling the CRT to protect eyes in case of implosion.

X-RAX-RA

X-RA

X-RAX-RA

Be aware of the instructions and procedures covering X-ray radiation. In solid-state receivers and monitors, the CRT is the only potential source of X-rays. Keep an accurate high voltage meter available at all times. Check meter calibration periodically. Whenever servicing a receiver, check the high voltage at various brightness levels to be sure it is regulating properly. Keep high voltage at rated value, NO HIGHER. Excessive high voltage may cause X-ray radiation or failure of associated components. DO NOT depend on protection circuits to keep voltage at rated value. When troubleshooting a receiver with excessive high voltage, avoid close contact with the CRT. DO NOT operate the receiver longer than necessary. To locate the cause of excessive high voltage, use a variable AC transformer to regulate voltage. In present receivers, many electrical and mechanical components have safety related characteristics which are not detectable by visual inspection. Such components are identified by a # on both the schematic and the parts list. For SAFETY, use only equivalent replacement parts when replacing these components.

GENERAL GUIDELINESGENERAL GUIDELINES

GENERAL GUIDELINES

GENERAL GUIDELINESGENERAL GUIDELINES

Perform a final SAFETY CHECK before returning receiver to customer. Check repaired area for poorly soldered connections, and check entire circuit board for solder splashes. Check board wiring for pinched wires or wires contacting any high wattage resistors. Check that all control knobs, shields, covers, grounds, and mounting hardware have been replaced. Be sure to replace all insulators and restore proper lead dress.

WARNINGWARNING

VICE

WARNING

VICE VICE

WARNINGWARNING

VICING VICING

VICING

VICING VICING

Y RADIAY RADIA

Y RADIA

Y RADIAY RADIA

THE HIGH THE HIGH

THE HIGH

THE HIGH THE HIGH

TION AND HIGH TION AND HIGH

TION AND HIGH

TION AND HIGH TION AND HIGH

OLOL

GE AND CRGE AND CR

GE AND CR

GE AND CRGE AND CR

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GE LIMITSGE LIMITS

GE LIMITS

GE LIMITSGE LIMITS

UTIONSUTIONS

UTIONS

UTIONSUTIONS

SAFETY CHECKS — FIRE AND SHOCK HAZARDSAFETY CHECKS — FIRE AND SHOCK HAZARD

SAFETY CHECKS — FIRE AND SHOCK HAZARD

SAFETY CHECKS — FIRE AND SHOCK HAZARDSAFETY CHECKS — FIRE AND SHOCK HAZARD

Cold LeakaCold Leaka

Cold Leaka

Cold LeakaCold Leaka

Unplug the AC cord, connect a jumper across the plug prongs, and turn the power switch on (if applicable). Use an ohmmeter to measure the resistance between the jumped AC plug and any exposed metal cabinet parts such as antenna screw heads, control shafts, or handle brackets. Exposed metal parts with a return path should measure between 1M ohms and 5.2M ohms. Parts without a return path must measure infinity.

Hot LeakaHot Leaka

Hot Leaka

Hot LeakaHot Leaka

Plug the AC cord directly into an AC outlet. DO NOT use an isolation transformer. Use a 1500 ohms, 10W resistor in parallel with a .15µF capacitor to connect between any exposed metal parts on the receiver and a good earth ground. (See figure below.) Use an AC voltmeter with at least 5000 ohms per volt sensitivity to measure the voltage across the resistor. Check all exposed metal parts and measure voltage at each point. Voltage measurements should not exceed .75VAC, 500µA. Any value exceeding this limit constitutes a potential shock hazard and must be corrected. If the AC plug is not polarized, reverse the AC plug and repeat exposed metal part voltage measurement at each point.

e Chece Chec

e Chec

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ks fks f

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e Current Chece Current Chec

e Current Chec

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or Receiveror Receiver

or Receiver

or Receiveror Receiver

s with Isolated Grs with Isolated Gr

s with Isolated Gr

s with Isolated Grs with Isolated Gr

oundound

ound

oundound

4679

SET 4679SET 4679

SET 4679

Error Codes Chart .................................. 1

GridTrace Location

High Voltage Shutdown Test .................. 1

IC Functions ........................................... 2

Important Parts Information ................... 1

Miscellaneous Adjustments .................... 1

Parts List ................................................. 4

Placement Chart ..................................... 1

Safety Precautions .................................. 1

Schematic Component Location ............ 3

Schematic Notes ..................................... 2

Schematics

Test Equipment....................................... 1

Tuner Information .................................. 1

INDEXINDEX

INDEX

INDEXINDEX

Main Board ..................................... 4

Audio ............................................... 3

Comb Filter ..................................... 3

Power Supply .................................. 2

System Control ................................ 3

Television ........................................ 2

Technical Service Data

GEGE

Model 32GT720YX4 (Chassis CTC203CF1)Model 32GT720YX4 (Chassis CTC203CF1)

Model 32GT720YX4 (Chassis CTC203CF1)

Model 32GT720YX4 (Chassis CTC203CF1)Model 32GT720YX4 (Chassis CTC203CF1)

Representative Model

or seror ser

or ser

or seror ser

Essential coEssential co

Essential co

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vision receivervision receiver

vision receiver

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HIGH HIGH

OLOL

HIGH

HIGH HIGH

Momentarily short BC14901 (see Q14901 base) to ground. The receiver should lose raster and sound. If receiver does not lose raster and sound, the shutdown circuit should be repaired. To resume normal operation, remove AC power for approximately 30 seconds and then turn the receiver on.

The listing of any available replacement part herein in no case constitutes a recommendation, warranty, or guarantee by SAMS Technical Publishing as to the quality and suitability of such replacement part. The numbers of the listed parts have been compiled from information furnished to SAMS Technical Publishing by the manufacturers of the specific type of replacement part listed.

Reproduction or use, without express permission, of editorial or pictorial content, in any manner, is prohibited. No patent liability is assumed with respect to the use of the information contained herein.

5436 West 78th Street Indianapolis, IN 46268-4149

Printed in the United States of America 5 4 3 2 1

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SET 4679 SET 4679

SET 4679

SET 4679 SET 4679

GE SHUTDOGE SHUTDO

GE SHUTDO

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WN WN

TESTTEST

TEST

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TESTTEST

03PF02045

UPC

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MODEL 32GT720YX4 (CHASSIS CTC203CF1)MODEL 32GT720YX4 (CHASSIS CTC203CF1)

MODEL 32GT720YX4 (CHASSIS CTC203CF1)

GEGE

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For Supplier Ad

For Supplier AdFor Supplier Ad

See PHOSee PHO

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Component locationsComponent locations

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Component locations

Component locationsComponent locations

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Coverage includes these additional models and chassis:

ModelsModels

Models

ModelsModels

32GT720YX6 CTC203CF3 32GT720YX8 CTC203CF3 35GT720YX2 CTC203CY1

JANUJANU

ARAR

Y Y

JANU

JANUJANU

2003 SET 4679 2003 SET 4679

2003 SET 4679

ARAR

Y Y

2003 SET 4679 2003 SET 4679

ChassisChassis

Chassis

ChassisChassis

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SET 4679 SET 4679

SET 4679

SET 4679 SET 4679

TUNER INFORMATION

TUNER TUNER

TUNER

TUNER TUNER

PinPin

(1) AGC 2.3V 2.7V 2.5V (2) NC 2.0V 5.1V 5.2V (3) +5V 5.1V 5.1V 5.1V (4) CLK 5.1V 5.1V 5.1V (5) DATA 5.1V 5.1V 5.1V (6) +5V 5.1V 5.1V 5.1V (7) +5V 5.1V 5.1V 5.1V (9) +32V 34.0V 34.0V 34.0V (11) IF 0V 0V 0V

NOTE: VHF Low Band voltages taken on channel 2.

VHF LoVHF Lo

VHF Lo

VHF LoVHF Lo

VHF High Band voltages taken on channel 7. UHF Band voltages taken on channel 14.

w Bandw Band

w Band

w Bandw Band

OLOL

GE CHARGE CHAR

GE CHAR

OLOL

GE CHARGE CHAR

VHF High BandVHF High Band

VHF High Band

VHF High BandVHF High Band

UHF BandUHF Band

UHF Band

UHF BandUHF Band

TUNER TUNER

TUNER

TUNER TUNER

(2)

(4)

(6)

TERMINAL GUIDETERMINAL GUIDE

TERMINAL GUIDE

TERMINAL GUIDETERMINAL GUIDE

(1)

(3)

(5)

(7)

(9)

(11)

MISCELLANEOUS ADJUSTMENTS

NOTE: All procedures require an antenna connected and power applied to the set.

HIGH HIGH

OLOL

HIGH

HIGH HIGH

Tune in a picture. Set brightness, contrast, and color to MINIMUM. Connect a high voltage probe to the CRT anode. High voltage should measure between 29kV and 32kV.

SERSER

VICE MENUVICE MENU

SER

VICE MENU

SERSER

VICE MENUVICE MENU

The following adjustment procedures are accessed thru a service menu. To access the service menu, turn the receiver on, press the menu button and hold it down while pressing the power button. While holding down the menu button, release the power button and press the volume + button. The screen will display a one line menu, on the left the parameter P0, and on the right the value of that parameter V0. Release buttons. Adjustments are made by selecting the proper parameter and changing the value of that parameter. To change the parameter number use channel up and down buttons. To adjust the current value of that parameter use volume + and - buttons. To access and change any of the adjustments, the proper parameter pass number must be entered. This information is listed at the beginning of the alignment. When these parameters are modified, the T-Chip and the corresponding EEPROM are updated. All service adjustments are bus controlled, except focus and screen.

NOTE: In order to adjust the RF AGC, audio or video levels, tuner, PIP, or stereo circuits, the ChipperCheck hardware and software must be used. This can be purchased from Thomson Electronics. Before making any changes to any of the values, record the On Set values.

SERSER

VICE ADJUSTMENT PARAMETERSVICE ADJUSTMENT PARAMETERS

SER

VICE ADJUSTMENT PARAMETERS

SERSER

VICE ADJUSTMENT PARAMETERSVICE ADJUSTMENT PARAMETERS

arameterarameter

arameter

arameterarameter

No.No.

No.

No.No.

OLOL

GE CHECKGE CHECK

GE CHECK

GE CHECKGE CHECK

arameter Namearameter Name

arameter Name

arameter Namearameter Name

On SetOn Set

On Set

On SetOn Set VV

aluealue

alue

aluealue

COLOR COLOR

COLOR

COLOR COLOR

NOTE: See Service Adjustment Parameters to change drive and bias values.

Press menu button for collapsed raster service line. Disconnect the antenna. Preset the red, green, and blue drive values to 32. Adjust screen control for a service line that is just visible. Adjust red, green, and blue drives to obtain a white raster. Check the low light to high light gray scale tracking. Repeat the procedure, if necessary, to obtain the best performance.

aluealue

alue

aluealue

RangRang

Rang

RangRang

TEMPERATEMPERA

TEMPERA

TEMPERATEMPERA

CommentComment

Comment

CommentComment

TURETURE

TURE

TURETURE

0 Pass number for service

adjustment parameters. Must set to 76 - May not advance until value is set to 76.

1 Error Code 1 0 0 - 255 Displays the first error detected. Set to 0 before exiting.

See Error Codes Chart.

2 Error Code 2 0 0 - 255 Displays the second error detected. Set to 0 before exiting.

See Error Codes Chart.

3 Error Code 3 0 0 - 255 Displays the last error detected. Set to 0 before exiting.

See Error Codes Chart. 4 Horizontal Phase 10 0 - 15 Tune in a crosshatch pattern, adjust to center the pattern on the screen. 5 EW DC (Width) 16 0 - 31 Tune in a crosshatch pattern, adjust for slight horizontal overscan. 6 EW Amplitude 8 0 - 15 Set value to 8. 7 EW Tilt 8 0 - 15 Set value to 8. 8 Top Corner Pin Correction 2 0 - 7 Set value to 2. 9 Bottom Corner Pin Correction 2 0 - 7 Set value to 2. 10 Vertical DC 33 0 - 63 Tune in a crosshatch pattern, adjust to center vertically. 11 Vertical Size 84 0 - 127 Tune in a crosshatch pattern, adjust for slight vertical overscan. 12 Vertical Countdown Mode 0 0 - 3 Set value to 0. ( 0 = Standard, 1 = Non-Standard, 2 = 50Hz, 3 = 48Hz ) 13 Red Bias 30 0 - 127 Press menu button on the TV set for setup line. 14 Green Bias 15 0 - 127 Press menu button on the TV set for setup line. 15 Blue Bias 34 0 - 127 Press menu button on the TV set for setup line. 16 Red Drive 41 0 - 63 17 Green Drive 33 0 - 63 18 Blue Drive 32 0 - 63 19 Gemstar Horizontal OSD Position 166 0 - 255 Set value to 166. 20 Gemstar Vertical OSD Position 68 0 - 255 Set value to 68. 21 Gemstar PIP Horizontal Position 40 0 - 255 Set value to 40. 22 Gemstar PIP Vertical Position 43 0 - 255 Set value to 43. 23 Gemstar PIP Window Vertical Size 3 0 - 13 Set value to 3.

ERROR CODES CHART

ErrErr

or Codeor Code

Err

or Code

ErrErr

or Codeor Code

DECDEC

DEC

DECDEC

0 00 No error code 1 01 16.0V fault 16.0V STBY source is failing. 3 03 12.0V run fault 12.0V source is failing. 4 04 T4 Chip Run supply failed. 8 08 T4 Chip X-ray protection caused high voltage shutdown. 9 09 T4 Chip (POR) Power supply problem at (POR) power on reset. 10 0A F2 PIP module error (POR) Power supply problem at (POR) power on reset/PIP. 11 0B Stereo decoder (POR) Power supply problem at reset/Stereo decoder. 16 10 Run IIC Bus held low Run IIC clock or data held low. 18 12 Standby IIC Bus held low Standby IIC clock or data held low. 23 17 Gemstar Board Guide fatal error on set using Gemstar Board. 24 18 Gemstar Board Task monitor error on set using Gemstar Board. 25 19 Gemstar Board Watchdog error on set using Gemstar Board. 26 1A Gemstar Board Task monitor error on set using Gemstar Board. 32 20 Gemstar Board CPU error on set using Gemstar Board. 34 22 Gemstar Board Gemstar fails to acknowledge. 44 2C F2 PIP module error F2PIP fails to acknowledge. 102 66 Octal DAC Octal DAC fails to acknowledge. 128 80 Stereo decoder Stereo decoder fails to acknowledge. 160 A0 Main or PIP tuner EEPROM Main or PIP tuner EEPROM fails to acknowledge. 186 BA T4 Chip T4 Chip fails to acknowledge. 196 C4 Main tuner PLL/DAC Main tuner PLL IC fails to acknowledge. 198 C6 Main tuner PLL/DAC Main tuner DAC IC fails to acknowledge.

ERRERR

OR CODESOR CODES

ERR

OR CODES

ERRERR

OR CODESOR CODES

If certain failures occur, the matching error codes will be stored in the EEPROM. These error codes will be displayed in parameters 1, 2, and 3. The first failure error code will be stored at parameter 1 and the second failure error code will be stored at parameter 2. Parameter 3 will be updated to display the most recent failure occurred in the chassis. If a failure of a bus IC occurred, the normal acknowledgment checking of that bus will be disabled in the service mode and the address of that IC which failed will be stored in one of the error code parameters. After every repair is done to the chassis it is recommended to check the error code parameters, and reset them back to value 0.

HEXHEX

HEX

HEXHEX

ErrErr

or Locationor Location

Err

or Location

ErrErr

or Locationor Location

Condition IndicatedCondition Indicated

Condition Indicated

Condition IndicatedCondition Indicated

SET 4679 PSET 4679 P

SET 4679 P

SET 4679 PSET 4679 P

ImporImpor

tant Ptant P

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Impor

tant P

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ν The parts listed here are those not usually available from a well-stocked supply cabinet or bin.

ν Where items may be replaced with equivalent parts, several alternates are shown from participating vendors.

ν On the parts lists, safety items are marked with a

these items.

ν When ordering parts, state the model number, part number, and description.

Many of these parts are available from your local Sams authorized distributor or the manufacturer of the equipment. Call Sams for the name of your nearest distributor:

tant Ptant P

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# #

# to remind you that only exact replacements are recommended for

# #

Obtaining PObtaining P

Obtaining P

Obtaining PObtaining P

ts Inf

ts Infts Inf

ormationormation

ormation

ormationormation

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tsts

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tsts

800-428-7267

Or consult the Sams

Information on test equipment and replacement parts is listed in these pages for the following participating vendors. Consult the Sams

ν NTE Electronics, Inc. (NTE)

Annual Index

for the address of the original equipment manufacturer.

arar

ticipating ticipating

ticipating

arar

ticipating ticipating

for their current address.

ν Sencore, Inc.

endorendor

endor

endorendor

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TEST EQTEST EQ

TEST EQ

TEST EQTEST EQ

Test equipment listed by participating manufacturer illustrates typical or equivalent equipment used by Sams engineers to obtain measurements. This equipment is compatible with most types used by field service technicians.

EquipmentEquipment

Equipment

EquipmentEquipment

Oscilloscope SC3100 Generators

RGB CM2125 Multiburst Signal VG91 Color Bar VG91

TV Stereo VG91 Digital VOM SC3100 Frequency Meter SC3100 Hi-Voltage Probe HP200 Accessory Probes TP212

Sencore No.Sencore No.

Sencore No.

Sencore No.Sencore No.

UIPMENTUIPMENT

UIPMENT

UIPMENTUIPMENT

EquipmentEquipment

Equipment

EquipmentEquipment

Isolation Transformer PR570 Capacitance Analyzer LC102 CRT Analyzer CR7000 AC Leakage Tester PR570 Inductance Analyzer LC102 Flyback Yoke Tester TVA92 Field Strength Meter SL753 Transistor Tester TF46 Horizontal Analyzer HA-2500 Video Analyzer VG91, TVA92

Sencore No.Sencore No.

Sencore No.

Sencore No.Sencore No.

GE MODEL 32GT720YX4 (CHASSIS CTC203CF1)

GE MODEL 32GT720YX4 (CHASSIS CTC203CF1)GE MODEL 32GT720YX4 (CHASSIS CTC203CF1)

SET 4679 PSET 4679 P

SET 4679 P

SET 4679 PSET 4679 P

e 1e 1

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SET 4679 SET 4679

SET 4679

SET 4679 SET 4679

+ 11 hidden pages