Sharp 37GQ-21S, 37GQ-20S Service Manual

37GQ-20S 37GQ-21S

SERVICE MANUAL

SEJB37GQ2*S02

Issued: 9th June ‘00

SQUAD CHASSIS

PAL SYSTEM COLOUR TELEVISION

37GQ-20S

MODELS:

In the interests of user safety (required by safety regulations in some countries) the set should restored to its original condition and only parts identical to those specified should be used.

37GQ-21S

CONTENTS

ELECTRICAL SPECIFICATION.......................2

IMPORTANT SERVICE NOTES.......................3

SERVICE ADJUSTEMENTS.............................4

PRINTED WIRING BOARDS...........................11

SHARP CORPORATION

SCHEMATIC DIAGRAM, WAVE FORMS..... .13

PART LIST.......................................................18

TROUBLESHOOTING TABLES......................23

This document has been published to be used for after sales service only.

37GQ-20S 37GQ-21S

ELECTRICAL SPECIFICATIONS

•Power Input .......................220V-240 Volts AC 50Hz

•Power Consumption

Normal Operating...................................30W

Stand-by Operating................................7.5W

(Method IEC60107)

•Audio Power Output Rating .....................2W (MPO)

Speaker............................32

Convergence.........................Self Converging System

Focus....................................Bi-Potencial Electrostatic

Sweep Deflection...........................................Magnetic

•Picture Intermediate Frecuencies

B/G...........................................................38.9MHz

•White Level Set brightness control to get total picture tube cathode current of 600 milliamperes under no signal condition. Maximum necessary correction of each picture tube cathode current to get 8550 degree K-20 MPCD screen temperature should not exceed 15% of its original value.

Ω 2W, 8cm Round, 1pc

•Sound Carrier Trap

B/G.......................................................33.4MHz

•Adjacent Sound Carrier Trap

B/G.............................................................40.4MHz

•Adjacent Picture Carrier Trap

B/G.......................................................30.9MHz

•Aerial Input Impedance

VHF/UHF...........................75 ohm Unbalanced

•Tuning Ranges

B/G............................48.25MHz thru 855.25 MHz

CATV Special Channels

X=0.290 Y=0.300

Specifictions are subject to change without prior notice.

W ARNING

The chassis in this receiver is partially live. Alwais use an isolation transformer when servicing this chassis. To prevent electric shock, do not remove cover. No user-serviceable parts inside. Refer servicing to qualified service personnel.

MODEL DESTINATION & DIFFERENCES:

37GQ-20S DE: Autria 37GQ-20S DES: Germany (Silver) 37GQ-20S ES: Spain 37GQ-20S IT : Italy

37GQ-20S NL: Holland 37GQ-20S SE: Sweden 37GQ-21S ESY: Spain (Yellow, with headphones) 37GQ-21S ESR: Spain (Red, with headphones)

37GQ-20S 37GQ-21S

IMPORT ANT SERVICE NOTES

Maintenance and repair of this receiver should be done by qualified service personnel only .

SERVICING OF HIGH VOLTAGE SYSTEM AND PICTURE TUBE

When servicing the high voltage system, remove static charge from it by connecting a 10K ohm resistor in series with an insulated wire (such as test probe) between picture tube ground tag and high voltage lead. (AC line cord should be disconnected from AC outlet).

1. The Picture tube in this receiver employs Integral Implosion protection.

2. Replace with tube of the same type number for continued safety .

3. Do not lift picture tube by the neck.

4. Handle the picture tube only when wearing shatterproof goggles and after discharging the high voltage completely .

X-RAY

This receiver is designed so that any X-Ray radiation is kept to an absolute minimum. Since certain malfunctions and servicing may produce potentially hazardous radiation with prolonged exposure at close range, the following precautions should be observed:

1. When repairing the circuit, be sure not to increase the high voltage to more than 25.5 KV , (at beam 1000µΑ) for the set.

2. T o keep the set in a normal operation, be sure to make it function on 22.4KV 800µΑ) in the case of the set. The set has been factory - adjusted to the above mentioned high voltage. Always check the high voltage if there is any possibility that it might have changed as a result of the repair.

3. Do not substitute a picture tube with unauthorized types and/or brands which may cause excess X-Ray radiation.

±1.5KV (at beam

BEFORE RETURNING THE RECEIVER

In addition to the above checks, the following safety checks should also be carried out before returning the unit to the user .

1. Inspect all leads and dress to make certain that the leads are not pinched or that hardware is not lodged between the chassis and other metal parts.

2. Inspect all protective devices such as non-metallic control knobs, insulating fish papers, cabinet backs, adjustment and compartment covers or shields, insolation resistor-capacity networks, mechanical insulators etc.

37GQ-20S 37GQ-21S

SERVICE ADJUSTMENT

•SERVICE MODE FUNCTION

This mode funtion is provided to assist with the settings of those adjustments that may vary from one Picture Tube to another, or between models.

In order to use the Service Mode

1. Press main switch to OFF.

2. Connect Test Pattern signal to antenna terminal.

3. Press ∨ , CH ∨ and main switch to ON simultaneosly or press ∧ , CH ∧ and main switch to ON simultaneosly.

4. -SERVICE- will appear on screen. Service mode is now entered.

5. Select adjustment using buttons ∧ CH ∧. To exit Service Mode, press main switch to OFF or press MENU button on R/C.

a. b. c. d. e.

f. g.

h. i. j. k. l. m. n.

Displayed on screen

SERVICE NVM AGC GAIN AGC STR PLL PAL

AUTO B-GAIN

G-GAIN G-DC R-GAIN R-DC HOR POS VERT POS VERT AM

Hexadecimal /

Decim. Range

00 ∼ 03H

00 ∼ 63H S, L, VL, N 4-43, 3-58,

SECAM, NTSC

4-43,NTSC 3-58,

AUTO PNS,

AUTO PN

AUTO, 50HZ,

60HZ 0 ∼ 63d 0 ∼ 63d 0 ∼ 63d 0 ∼ 63d 0 ∼ 63d 0 ∼ 63d 0 ∼ 63d 0 ∼ 15d

Function

Indicates operative Service Mode. Access to NVM memory Auto Gain Control Auto Gain Starting Point Line PLL time constant Colour system.

Field Frequency Blue Gain

Green Gain Green Cut Red Gain Red Cut Horizontal Position shift V ertical Position shift V ertical Amplitude shift

6. For « a » Selection: NVM storage location settings variants.

BANK POS VALUE X XXH XXH Assigned value

Storage location Memory Bank

In order to have access to NVM «MENU» button should be pressed. To obtain a higher or lower Memory Bank, buttons ∨ ∧ should be pressed respectively. To have access to the desired Storage Location,

buttons ∨ CH ∧ should be pressed, as required to obtain a higher or lower location, respectively.

37GQ-20S

NVM LIST DESCRIPTION

BANK ADDRESS DESCRIPTION VALUE 00H 00H ZONE FOR TUNNING INFORMATION (BEGIN) CAH

3BH ZONE FOR TUNNING INFORMATION (END) 10H 3CH STAND BY: 44H -> ON

40H -> OFF

44H

3DH OPTION BYTE:

10XXXXXX -> HOTEL MODE 1 (START IN PRG1. NO TUNNING OPTION. VOLUME LIMITATION). 11XXXXXX -> HOTEL MODE 2 (START IN PRG 1. NO TUNING OPTION. VOLUME LIMITATION. START IN SCART MODE. OUT FROM STDBY WITH SSW. XXDDDDDD -> VOLUME ATTENUATION: 0AH -> 100%, 00H -> 0%

00H

3EH DIODE_NVM:

XXXXXXX0 -> SYMBOLIC OSD. XXXXXXX1 -> CHARACTER OSD XXXXX1XX -> ENGLISH LANGUAGE.

04H

3FH DIODE2_NVM:

XXXXXXX1 -> FRENCH STANDARD XXXXX01X -> BG STANDARD XXXXX10X -> L/L’ STANDARD XX1XXXXX -> AUDIO FOR UK X1XXXXXX -> AUTOINSTALLATION ON 1XXXXXXX -> ONLY UHF BAND.

00H

01H 00H ZONE FOR TUNNING INFORMATION (BEGIN) 10H

3BH ZONE FOR TUNNING INFORMATION (END) 10H 3DH UHFLOW: LOW WINDOW LIMIT FOR UHF BAND 00H 3EH VHF3LOW: LOW WINDOW LIMIT FOR VHF3 BAND 00H 3FH VHF1LOW: LOW WINDOW LIMIT FOR VHF1 BAND 00H

02H 00H RESERVED ZONE FOR PROGRAMME NAMES (BEGIN) 24H

3FH RESERVED ZONE FOR PROGRAMME NAMES (END) 24H

37GQ-21S

Bear in mind that, for storage location indication a hexadecimal numerical system is used, instead of a decimal system.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, 10, 11, ......19, 1A, 1B, 1C, 1D, 1E, 1F, 20, 21, ....., 99, 9A, 9B,

9C, 9D, 9E, 9F, A0, A1, ....., B0, ....., C0, ....., D0, .....E0, ....., F0, F1, F2, F3, F4, F5, F6, F7, F8, F9, FA,

FB, FC, FD, FE, FF. From the last location FF to the first 00 can be reached by increasing and from first to last by decreasing. Once the storage location to be varied has been selected, its value can be modified by the bits that form part of the storage location numerical buttons, numbers «0» to «7», respectively. This swithches the binary number from and between 0 and 1 each time one of the buttons is pressed.

«0»:20=1, «1»: 21=2, «2»: 22=4, ...

7. For «b,c» and «g» thru «n» selections: Adjustment to a selection can be made by pressing buttons ∨ ∧.

8. For «d» thru «f» selections: Adjustment to a selection can be made by pressing button ∧.

37GQ-20S

03H 00H ONE CHIP REGISTER 00: 80H

01H ONE CHIP REGISTER 01: 05H 02H ONE CHIP REGISTER 02: 9FH 03H ONE CHIP REGISTER 03: 20H 04H ONE CHIP REGISTER 04: 00H 05H ONE CHIP REGISTER 05: CCH 06H ONE CHIP REGISTER 06: 44H 07H ONE CHIP REGISTER 07: 34H 08H ONE CHIP REGISTER 08: 21H 09H ONE CHIP REGISTER 09: A1H 0AH ONE CHIP REGISTER 0A: 32H 0BH ONE CHIP REGISTER 0B: B2H 0CH ONE CHIP REGISTER 0C: 32H 0DH ONE CHIP REGISTER 0D: 20H 0EH ONE CHIP REGISTER 0E: 20H 0FH ONE CHIP REGISTER 0F: 18H 10H ONE CHIP REGISTER 10: 15H 11H ONE CHIP REGISTER 11: 00H 12H ONE CHIP REGISTER 12: 00H 13H ONE CHIP REGISTER 13: 20H 14H ONE CHIP REGISTER 14: 20H 15H ONE CHIP REGISTER 15: 00H 16H ONE CHIP REGISTER 16: 1FH 17H ONE CHIP REGISTER 17: 20H 18H ONE CHIP REGISTER 18: 2BH 19H ONE CHIP REGISTER 19: 00H 1AH ONE CHIP REGISTER 1A: 90H 1BH ONE CHIP REGISTER 1B: 90H 1CH ONE CHIP REGISTER 1C: 90H 1DH ONE CHIP REGISTER 1D: 00H 1EH ONE CHIP REGISTER 1E: 00H 1FH ONE CHIP REGISTER 1F: 00H 20H VPOS_50 (VERTICAL POSITION) 4/3 50 Hz. 12H 21H VAMP_50 (VERTICAL AMPLITUDE) 4/3 50 Hz 0FH 22H VPOS_60 (VERTICAL POSITION) 4/3 60 Hz 0FH 23H VAMP_60 (VERTICAL AMPLITUDE) 4/3 60 Hz 0FH 24H HSHIFT_60 (HORIZONTAL SHIFT) 60Hz 1DH 25H HSHIFT_50 (HORIZONTAL SHIFT) 50Hz 22H 26H FINVFH: STEP FOR FINE TUNING IN VHF BAND 00H 27H VHF1_STEP: THICK TUNING STEP FOR VHF1 BAND A4H 28H VHF3_STEP: THICK TUNING STEP FOR VHF3 BAND 55H 29H UHF_STEP: THICK TUNING STEP FOR UHF BAND 55H 2AH LP_COARSE: THICK TUNING ADJUSTMENT FOR L’ 02H 2BH BG_COARSE: THICK TUNING ADJUSTMENT FOR L AND BG 0AH 2CH BG_FINE: FINE TUNING ADJUSTMENT FOR L AND BG 00H 2DH LP_FINE: FINE TUNING ADJUSTMENT FOR L’ 00H 2EH DELAY SEARCH:

XXXXXXX0 -> SHOWS ‘PROGRAMME –‘ DURING AUTOSEARCH. XXXXXXX1 -> DHOWS ‘AUTO SEARCH’ DURING AUTOSEARCH

00H

2FH VHF1_SP: STEP FOR AUTO SEARCH IN VHF1 BAND 0AH 30H VHF3_SP: STEP FOR AUTO SEARCH IN VHF3 BAND 05H 31H UHF_SP: STEP FOR AUTO SEARCH IN UHF BAND 03H 32H OLD_PROGRAM: FOR FLASHBACK RETURN 02H 33H UHFHIGH: UPPER WINDOW LIMIT FOR UHF 01H 34H VHF3HIGH: UPPER WINDOW LIMIT FOR VHF3 01H

37GQ-21S

37GQ-20S

35H VH F1HIGH: UPPER WINDOW LIMIT FOR V HF1 01H 36H PRG _NUMBER: CURREN T PROGRA MME NUMBE R 03H 37H W AITSUP: UPPER LIMI T DELAY TIME FOR A UTOSEARCH. 0FH 38H W AITINF: LOWER LIMIT DELA Y TIME FOR A UTOSEARCH 03H 3BH SCART BL OKING:

- 00H = NO SCARTBLOCKING

- 01H = SCART BLOCKING W HEN ANY PR. IS IN CHILD

LOCK MODE.

00H

Just for

3CH RET_COL: DE LAY IN COL OUR IDENT IFICATION IN AUTO

M O DE.

40H

3FH CHECK SUM 7EH

04H 00H ONE CH IP REGISTER 00: 80H

01H ON E CHIP REGISTER 01: 05H 02H ON E CHIP REGISTER 02: 9FH 03H ON E CHIP REGISTER 03: 20H 04H ON E CHIP REGISTER 04: 00H 05H ON E CHIP REGISTER 05: CCH 06H ON E CHIP REGISTER 06: 44H 07H ON E CHIP REGISTER 07: 34H 08H ON E CHIP REGISTER 08: 21H 09H ON E CHIP REGISTER 09: A1H 0AH ON E CHIP REGISTER 0A: 32H 0BH ONE CH IP REGISTER 0B: B2H 0CH ONE CH IP REGISTER 0C: 32H 0DH ON E CHIP REGISTER 0D: 20H 0EH ON E CHIP REGISTE R 0E: 20H 0FH ONE CH IP REGISTER 0F: 18H 10H ON E CHIP REGISTER 10: 1FH 11H ON E CHIP REGISTER 11: 00H 12H ON E CHIP REGISTER 12: 00H 13H ON E CHIP REGISTER 13: 20H 14H ON E CHIP REGISTER 14: 20H 15H ON E CHIP REGISTER 15: 00H 16H ON E CHIP REGISTER 16: 1FH 17H ON E CHIP REGISTER 17: 20H 18H ON E CHIP REGISTER 18: 2BH 19H ON E CHIP REGISTER 19: 00H 1AH ON E CHIP REGISTER 1A: 90H 1BH ONE CH IP REGISTER 1B: 90H 1CH ONE CH IP REGISTER 1C: 90H 1DH ON E CHIP REGISTER 1D: 00H 1EH ON E CHIP REGISTE R 1E: 00H 1FH ONE CH IP REGISTER 1F: 00H 20H VPO S_50 (VERTICAL POSITION) 4/3 50 Hz. 12H 21H VA MP_50 (VERTICAL AMPLITU DE) 4/3 50 Hz 0FH 22H VPO S_60 (VERTICAL POSITION) 4/3 60 Hz 0FH 23H VA MP_60 (VERTICAL AMPLITU DE) 4/3 60 Hz 0FH 24H HSH IFT_60 (HORIZONT AL SHIFT) 60Hz 1DH 25H HSH IFT_50 (HORIZONT AL SHIFT) 50Hz 22H 26H FINV FH: STEP FOR FINE T UNING IN VHF BAND 00H 27H VH F1_STEP: THICK TUNI NG STEP FOR VH F1 BAND A4H 28H VH F3_STEP: THICK TUNI NG STEP FOR VH F3 BAND 55H 29H UH F_STEP: THICK TUNING STEP FO R UHF BA ND 55H 2AH LP_C OARSE: THICK TUNING A DJUSTMENT FOR L’ 02H 2BH BG_COA RSE: THICK TU NING ADJU STMENT FOR L AND BG 0AH 2CH BG_FINE: FINE TUNING ADJUSTMENT FOR L AND BG 00H 2DH LP_FINE : FINE TUNING ADJUSTMEN T FOR L’ 00H 2EH DE LAY SEAR CH:

XXXXXX X0 - > S H OW S ‘PR O GR A MME – ‘ DURIN G AU T OS E A RCH . XXXXXX X1 - > D HO WS ‘AUT O S E ARC H’ DURIN G AU T OS E ARC H

00H

37GQ-21S

Do not use.

UK models

37GQ-20S

2FH VHF1_SP: STEP FOR AUTO SEARCH IN VHF1 BAND 0AH 30H VHF3_SP: STEP FOR AUTO SEARCH IN VHF3 BAND 05H 31H UHF_SP: STEP FOR A UTO SEARCH IN VHF BAND 03H 32H OLD_PROGRAM: FOR FLASH BACK RETURN 02 H 33H UHFHIGH: UPPER WINDOW L IMIT FOR UHF 01H 34H VHF3HIGH: UPPER WINDOW L IMIT FOR VHF3 01H 35H VHF1HIGH: UPPER WINDOW L IMIT FOR VHF1 01H 36H PRG_NUM BER: CURRENT PROG RAMME NUMBER 03H 37H WAITSUP: UPPER LIMIT DELAY TIME FOR AUTOSEARCH. 0FH 38H WAITINF: LO WER LIMIT DELAY TIME FOR AUTOSEARCH 03H 3BH SCART B LOKING:

- 00H = NO SCARTBLOCKING

- 01H = SCART BLOCKING WHEN ANY PR. IS IN CHILD LOCK M ODE.

00H

Just for

3CH RET_COL: DELAY IN COLOUR IDEN TI FI CATION IN AUTO

MODE.

40H

3FH CHECK SUM 7EH

05H 00H ONE CHIP REGISTER 00: 80H

01H ONE CHIP REG ISTER 01: 05H 02H ONE CHIP REG ISTER 02: 9FH 03H ONE CHIP REG ISTER 03: 20H 04H ONE CHIP REG ISTER 04: 00H 05H ONE CHIP REG ISTER 05: CCH 06H ONE CHIP REG ISTER 06: 44H 07H ONE CHIP REG ISTER 07: 34H 08H ONE CHIP REG ISTER 08: 21H 09H ONE CHIP REG ISTER 09: A1H 0AH ONE CHIP REGISTER 0A: 32H 0BH ONE CH IP REGISTER 0B: B2H 0CH ONE CH IP REGISTER 0C: 32H 0DH ONE CHIP REGISTER 0D: 20H 0EH ONE CHIP REGISTER 0E: 20H 0FH ONE CH IP REGISTER 0F: 18H 10H ONE CHIP REG ISTER 10: 1FH 11H ONE CHIP REG ISTER 11: 00H 12H ONE CHIP REG ISTER 12: 00H 13H ONE CHIP REG ISTER 13: 20H 14H ONE CHIP REG ISTER 14: 20H 15H ONE CHIP REG ISTER 15: 00H 16H ONE CHIP REG ISTER 16: 1FH 17H ONE CHIP REG ISTER 17: 20H 18H ONE CHIP REG ISTER 18: 2BH 19H ONE CHIP REG ISTER 19: 00H 1AH ONE CHIP REGISTER 1A: 90H 1BH ONE CH IP REGISTER 1B: 90H 1CH ONE CH IP REGISTER 1C: 90H 1DH ONE CHIP REGISTER 1D: 00H 1EH ONE CHIP REGISTER 1E: 00H 1FH ONE CH IP REGISTER 1F: 00H 20H VPOS_50 (VERTICAL POSITION) 4/3 50 Hz. 12H 21H VAMP_50 (VERT ICAL AMPLITUDE) 4/3 50 Hz 0FH 22H VPOS_60 (VERTICAL POSITI ON) 4/3 60 Hz 0FH 23H VAMP_60 (VERT ICAL AMPLITUDE) 4/3 60 Hz 0FH 24H HSHIFT_60 (HORIZONTAL SHIFT) 60Hz 1DH 25H HSHIFT_50 (HORIZON TAL SHIFT) 50Hz 22H 26H FINVFH: STEP FOR FINE TUNING IN V HF BAND 00H 27H VHF1_STEP: TH IC K TUNING STEP FOR VHF1 BAND A4H 28H VHF3_STEP: TH IC K TUNING STEP FOR VHF3 BAND 55H 29H UHF_STEP: THIC K TUNING STEP FOR UHF BAND 55H 2AH LP_COARSE: THICK TUNING ADJUSTMENT FOR L’ 02H

37GQ-21S

Do not use.

UK models

2BH BG_COA R SE : T HICK TUNING ADJUS TMENT FOR L AND BG 0AH 2CH BG_FINE: FINE TUNING ADJUSTMENT F OR L AN D BG 00 H 2DH LP_FINE: FINE TUNING ADJUSTMENT FOR L’ 00H 2EH DELAY SEARCH:

XXXXXXX 0 -> SHOWS ‘PROGRAMME –‘ DURI NG AU T OS EARCH . XXXXXXX 1 -> DHOWS ‘AUTO SEA RCH’

DURI NG AUTOSEARCH 2FH VHF1_SP: STEP FOR AUTO SEARCH IN VHF1 BAND 0AH 30H VHF3_SP: STEP FOR AUTO SEARCH IN VHF3 BAN D 05H 31H UHF_SP: STEP FOR A UTO SEARCH IN VHF BAND 03H 32H OLD_PROGRAM: FOR FLASHBACK RETUR N 02H 33H UHFHIGH: UPPER WINDOW LIMIT FOR UHF 01H 34H VHF3HIGH: UPPE R WINDOW LIMIT FOR VHF 3 01H 35H VHF1HIGH: UPPE R WINDOW LIMIT FOR VHF 1 01H 36H PRG_NUM BER: CURRENT PROGR AMME NUMBER 03H 37H WAITSUP: UPPER L IMI T DELAY TI ME FOR AUTO SEARCH. 0FH 38H WAITINF: LO WER LIMIT D ELAY TIME FOR AUTOSEARCH 03H 3BH SCART B LOKING:

- 00H = NO SCARTBLOCKING

- 01H = SCART BLOCKING WHEN ANY PR. IS IN CHILD LOCK M ODE.

3CH RET_COL: DELAY IN COLOUR IDEN TI FI CATION IN AUTO

MODE.

3FH CHECK SUM 7EH

00H

Do not use. Just for UK models

40H

37GQ-20S 37GQ-21S

••

•PIF/AGC Adjustement

••

1. B/G AFT Adjustment Connect the output of SSG (Standard Signal

Generator) to the tuner IF output terminal.

•SSG output 38.9 MHz (CW) ± 5 KHz.

•SSG output level: approx. 90 dBµV.

Enter into Service Mode.

Push «2» key on R/C. «FI OK» will appear.

Switch set OFF and ON again, setting is now

memorized.

2. RF-AGC STR Adjustment Receive the «COLOUR BAR» signal (Channel E-

12). Signal strength: 57 dBµV. Enter into Service Mode.

Push CH until AGC STR appears on screen.

Push «7» key of R/C.«AGC OK» will appear.

Switch set OFF and ON again, setting is now

memorized.

••

•Screen Adjustement

••

3. Focus Adjustment Apply mains voltage of 220V AC/50HZ to TV.1.

Receive Philips pattern signal to a level

between 60 and 80 Set contrast to 10/10, brightness to 5/10

dBµV.

and colour 0/10. Adjust focus potentiometer to obtain

maximum definition.

4. G2 Adjustment

Apply mains voltage of 220V AC/50HZ to TV.

Receive cross hatch pattern signal to a level

between 60 and 80 dBµV. Apply High Voltage Probe to Pin 8 of CRT socket

Adjust G2 potentiometer until obtaining 525V

±10%. Check BKGD. If it is necessary adjust BKGD

according to instructions detailed in the next page.

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