Sharp 37GT-28FP User manual

1
37GT-28FP
SHARP CORPORATION
CONTENTS
PAL / SECAM SYSTEM COLOUR TELEVISION
S0037GT28FP00
SQUAD-T CHASSIS
SERVICE MANUAL
In the interests of user safety (required by safety
regulationsinsomecountries)thesetshouldrestored
to its original condition and only parts identical to
those specified should be used.
MODEL 37GT-28FP
Issued:14th March 2002
This document has been published to
be used for after sales service only.
ELECTRICAL SPECIFICATION.......................3
IMPORTANT SERVICE NOTES.......................4
SERVICE ADJUSTMENTS...............................5
PRINTED WIRING BOARDS..........................12
COMPONENT LOCATION TABLES................14
ICs ADDITIONAL INFORMATION..................17
○○
SCHEMATIC DIAGRAM, WAVE FORMS.......24
BLOCK DIAGRAM..........................................30
TROUBLESHOOTING TABLES......................32
PART LIST.......................................................37
PACKING OF THE SET...................................42
REMOTE CONTROL DESCRIPTION..............43

2
37GT-28FP
Use this page to keep any special servicing information as Technical Report (Bulletin), Technical Information, etc.
If only part number changes are required, just change part number directly the part number in the Parts Listing Section.
If you need more information, please refer to the Technical Report (Bulletin).
SERVICE MANUAL UPDATE LOG SHEET
Part No.
Technical Report No.
Technical Bulletin No. Cause / Solution Page No. Application
Data /Serial No.

3
37GT-28FP
ELECTRICAL SPECIFICATIONS
•Power Input .......................220V-240 Volts AC 50Hz
•Power Consumption
•Audio Power Output Rating .....................2W (MPO)
Speaker............................32Ω2W, 8cm Round, 1pc
Normal Operating....................................30W
(Method IEC60107)
Stand-by Operating................................7.5W
•White Level
Setbrightnesscontroltogettotalpicturetubecathodecurrentof600uAundernosignalcondition.Maximum necessary
correction of each picture tube cathode current to get 8950 degree K-20 MPCD screen temperature should not
exceed 15% of its original value.
X=0.290 Y=0.284
Convergence.........................Self Converging System
Focus....................................Bi-Potencial Electrostatic
Sweep Deflection...........................................Magnetic
•Sound Carrier Trap
L’..........................................................40.4MHz
L...........................................................32.4MHz
B/G.......................................................33.4MHz
•Picture Intermediate Frecuencies
L’.........................................................33.9MHz
L, B/G..................................................38.9MHz
•Adjacent Sound Carrier Trap
L’..........................................................32.4MHz
L, B/G...................................................40.4MHz
•Adjacent Picture Carrier Trap
L’..........................................................41.9MHz
L...........................................................30.9MHz
B/G.......................................................30.9MHz
•Aerial Input Impedance
VHF/UHF...........................75 ohm Unbalanced
•Tuning Ranges
CATV Special Channels
L/L’..........................55.75MHz thru 855.25 MHz
B/G.........................48.25MHz thru 855.25 MHz
WARNING
The chassis in this receiver is partially hot. Use an isolation transformer between the line cord plug
and power receptacle, when servicing this chassis.
To prevent electric shock, do not remove cover. No user-serviceable parts inside. Refer servicing to
qualified service personnel.
Specifications are subject to change without prior notice.

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37GT-28FP
Only qualified service personnel are allowed to carry out mintenance and repair of this receiver.
Itis important thatthe static chargeisremovedfromthehigh voltage system whencarryingoutworkon
thereceiver. This can be achieved by connecting a 10K resistor (with a suitably insulated lead) from the
CRT cavity connectortothe CRTgroundtag.This must becarriedout with theACsupply disconnected
from the receiver.
Note the following:
•The CRT in this receiver employs Integral Implosion Protection.
•If the CRThas to be changed it MUST be replaced with the correct type for continued safe
working.
•DO NOT lift the CRT by its neck.
•When handing the CRT, ensure that shatterproof goggles are worn.
•Ensure that the CRT is discharge before handling.
X-RAY
Thisreceiverisdesignedtokeepanyx-rayemissiontoanabsoluteminimum.Somefaultconditions and
servicing procedures may produce potentially hazardous x-ray radiation levels. This is a problem when
in close proximity to the receiver for long periods of time. To reduce any risks associated with this,
please observe the following precautions:
1. When undertaking any servicing on this chassis, DO NOT increase the EHT to more than 30KV,
at a instantaneous beam current of 300µΑ).
2. Ensure that during normal operation the EHT does not exceed 27.5KV(at a beam current of
800µΑ). Thislevelhasbeenpre-setinthefactory.Alwayscheckthatthislevelhasnotbeenexceeded
after carrying out any repair on the receiver.
3. DO NOT replace the CRT with any other type than that specified in the parts listing as this may
cause excessive x-ray radiation.
BEFORE RETURNING THE RECEIVER TO THE CUSTOMER
Inadditiontotheabovechecks,thefollowingshouldalsobecarriedoutbefore returningthereceiver to
the customer.
1.Inspectalltheleadstoensurethattheyaredressedcorrectlyandthattheyarenotobstructedorpinched
by any other parts.
2.Ensurethatallprotectivedevicesareingoodcondition.Thesewillincludenonmetalliccontrolknobs,
insulating fish papers, cabinets backs, compartment covers or shields, mechanical insulators, etc.
IMPORTANT SERVICING NOTES
SERVICING OF HIGH VOLTAGE SYSTEM AND CRT

5
37GT-28FP
Indicates operative Service Mode
Auto Gain Control
Auto Frecquency Control Fine PAL B/G
Auto Frecquency Control Coarse SECAM B/G, L
Auto Frecquency Control Fine L’
Auto Frecquency Control Coarse L’
HorizontalShift
Vertical Shift
Verical Amplitud
Red Gain
Green Gain
Blue Gain
Red Cut Off
Green Cut Off
NVM Data Change
SERVICE ADJUSTMENT
Service Mode Function
XXXX
XX
XX
POS (Green)
VALUE (Red)
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
n.
-SERV-
AGC
AFT F
AFT C
AFT FL
AFT CL
H-SHFT
V-SHFT
V-AMPL
GAIN R
GAIN G
GAIN B
CUT R
CUT G
NVM
Displayed
on screen Hexadecimal /
Decim. Range Function
00∼ 3F
02∼ FE
00∼ 0F
02∼ FE
00∼ 0F
00∼ FF
00∼ 3F
00∼ 0F
00∼ 3F
00∼ 3F
00∼ 3F
00∼ 3F
00∼ 3F
00∼ 3F
00∼ FF
1. Turn the receiver on and ensure that it is tuned into a test pattern.
2. Turn the receiver off using the mains switch.
3. Press the volume down and channel up buttons together. See Fig. 1.
4. Continue pressing the volume down and channel up buttons while turning
the mains on using the mains switch. See Fig. 1.
5. Keep pressing the volume down and channel up buttons until the picture appears.
6. Release the two buttons and the receiver is now in the service mode.
To move between the various service mode functions, use the channel up and down buttons.
Use the volume buttons to change the data to the desired value.
The data will be stored automatically when exiting the service mode.
To exit the service mode, press the stand-by button on the remote control or turn the receiver off
with the mains switch.
On Screen
Display
(Blue)
}
}
3
4
CH
All required adjustments for servicing this TV set, may be done in «Service Mode», excepting G2 and FOCUS.
How to access the Service Mode
Fig. 1

6
37GT-28FP
Adjustment of Data within the NVM memory
To access the NVM memory, press the channel up buttonontheremote control until the NVM setting is reached. Note that
the NVM address is shown in green and the NVM value is shown in red. Each of the NVM values are stored as a
hexadecimalcode,each code comprises of two hexadecimal numbers. Each of these numbers will break downintoafour
bit binary code as in the example below.
Hex code A 5
Binary code 1010 0101
Button on remote to toggle Bit 7654 3210
Inthe example given above, the hexadecimal code is A5, the binary equivalentis10100101.The remote control button to
toggle each bit on or off (1 or a 0) is shown below the binary code. Therefore to change this to A6, remote control buttons
1 then 0 would have to be pressed.
Note: In the tables below appear b0, b1, b2,.........,b7, whose indicate the bit number:
b0 is the Least Significant Bit (LSB).
b7 is the Most Significant Bit (MSB).
VALUE DESCRIPTION ADDRESS
44 RESERVED
b7: x
b6: CO_BLK
b5: SVHS
b4: FRAME_BLK
b3: BLACK_ST_REF
b2: S_STD2
b1: S_STD1
b0: QSS
0F
38 RESERVED
b7: BLACK_ST
b6: COR
b5: CK_ON
b6: COR
b5: CK_ON
b4: VID_ST2
b3: VID_ST1
b2: CK_1
b1: CK_2
b0: CK_3
10
A5 SIGNATURE VALUE 11
32 TEMPERATURE RED 12
32 TEMPERATURE GREEN 13
32 TEMPERATURE BLUE 14
26 VERTICAL SHIFT 15
32 RED CUTOFF 16
32 GREEN CUTOFF 17
1F HORIZONTAL SHIFT 18
37 VERTICAL AMPLITUDE 19
08 LUMA DELAY
b6-b5:AUDIO OUT
b4-b5: 00
b3: LUMA DELAY SHIFT
b1-b2:00
b0: V OUT INHIBITION
1 A
VALUE DESCRIPTION ADDRESS
32 TEMPERATURE RED 00
32 TEMPERATURE GREEN 01
32 TEMPERATURE BLUE 02
26 VERTICAL SHIFT 50HZ 03
32 RED CUTOFF 04
32 GREEN CUTOFF 05
1F HORIZONTAL SHIFT 50HZ 06
37 VERTICAL AMPLITUDE 07
08 LUMA DELAY
b6-b5:AUDIO OUT
b4-b5: 00
b3: LUMA DELAY SHIFT
b1-b2:00
b0: V OUT INHIBITION
08
2C CAG ADJUSTEMENT VALUE 09
63 TV OPTIONS
b7: ENGLISH OSD
b6: AUTOINSTALLATION FIRST
OPTION
b5: CHILD LOCK ENABLED
b4: X
b3: UHF BAND ONLY
b2: BASIC HOTEL MODE
b1: AV FRONT ENABLED
b0: FP VERSION
0A
3A AFT COARSE FOR B/G AND L'
SYSTEMS 0B
38 AFT FINE FOR B/G AND L
SYSTEMS 0C
92 AFT FINE FOR L' SYSTEMS 0D
FF VOLUME LIMIT (MAXIMUM) 0E
NVM List Description

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37GT-28FP
VALUE DESCRIPTION ADDRESS
2C CAG ADJUSTEMENT VALUE 1B
63 TV OPTIONS
b7:
ENGLISH OSD
b6: AUTOINSTALLATION FIRST
OPTION
b5: CHILD LOCK ENABLED
b4: X
b3:
UHF BAND ONLY
b2:
BASIC HOTEL MODE
b1: AV FRONT ENABLED
b0: FP VERSION
1C
3A AFT COARSE FOR B/G AND L'
SYSTEMS 1D
38 AFT FINE FOR B/G AND L
SYSTEMS 1E
92 AFT FINE FOR L' SYSTEMS 1F
FF VOLUME LIMIT (MAXIMUM) 20
44 RESERVED
b7: X
b6: CO_BLK
b5: SVHS
b4: FRAME_BLK
b3: BLACK_ST_REF
b2: S_STD2
b1: S_STD1
b0: QSS
21
38 RESERVED
b7: BLACK_ST
b6: COR
b5: CK_ON
b6: COR
b5: CK_ON
b4: VID_ST2
b3: VID_ST1
b2: CK_1
b1: CK_2
b0: CK_3
22
A5 SIGNATURE VALUE 23
32 TEMPERATURE RED 24
32 TEMPERATURE GREEN 25
32 TEMPERATURE BLUE 26
26 VERTICAL SHIFT 27
32 RED CUTOFF 28
32 GREEN CUTOFF 29
1F HORIZONTAL SHIFT 2 A
37 VERTICAL AMPLITUDE 2B
08 LUMA DELAY
b6-b5:AUDIO OUT
b4-b5: 00
b3: LUMA DELAY SHIFT
b1-b2:00
b0: V OUT INHIBITION
2C
2C CAG ADJUSTEMENT VALUE 2D
63 TV OPTIONS
b7:
ENGLISH OSD
b6: AUTOINSTALLATION FIRST
OPTION
b5: CHILD LOCK ENABLED
b4: X
b3:
UHF BAND ONLY
b2:
BASIC HOTEL MODE
b1: AV FRONT ENABLED
b0: FP VERSION
2E
3A AFT COARSE FOR B/G AND L'
SYSTEMS 2F
VALUE DESCRIPTION ADDRESS
38 AFT FINE FOR B/G AND L
SYSTEMS 30
92 AFT FINE FOR L' SYSTEMS 31
FF VOLUME LIMIT (MAXIMUM) 32
44 RESERVED
b7: X
b6: CO_BLK
b5: SVHS
b4: FRAME_BLK
b3: BLACK_ST_REF
b2: S_STD2
b1: S_STD1
b0: QSS
33
38 RESERVED
b7: BLACK_ST
b6: COR
b5: CK_ON
b6: COR
b5: CK_ON
b4: VID_ST2
b3: VID_ST1
b2: CK_1
b1: CK_2
b0: CK_3
34
A5 SIGNATURE VALUE 35
A5 SIGNATURE VALUE 37
20 NVM SATURATION 38
05 OFFSET FOR VOLUME CURVE 39
1E VOLUME VALUE (DECIMAL) 3A
31 CONTRAST 3B
19 COLOR SATURATION 3C
20 BRIGHTNESS 3D
07 0,0,P5,P4,P3,P2,P1,P0
LUMA PEAKING VALUE LUPK 3E
01 CURRENT PROGRAM 3F
00 TV STATUS: 00H : TV ON
FFH : TV STBY 40
36 FACTORY CONTRAST 41
19 FACTORY COLOR SATURATION 42
20 FACTORY BRIGHTNESS 43
06 FACTORY PEAKING
b5-b0: LUMA PEAKING VALUE 44
16 END OF HORIZONTAL CLAMP
PULSE 45
19 OSD STATUS
b6: X
b5: PIN ENABLED
b4: CLOCK
b3 R8/30
b2: FRONT LOCK
b1: AV LOCK
b0: E_NORMALIZED PICTURE
46
06 TXT AND OSD OPTIONS
b7: X
b6: ROW 8/30 (TXT)
PREPROCESSING FOR UK
b5: PASSWORD ON/OFF
b4: OSD REMAINING TIME
b3: SIZE OSD PROG: 0= 14”
1= 21”
b2: VPS LOCK ON / OFF
b1: FLOF
b0: TOP
47

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37GT-28FP
VALUE DESCRIPTION ADDRESS
00 BEGINING OF HORIZONTAL
CLAMP PULSE. 48
1F VOLTAGE TO CHANGE TO L-L'
SYSTEM 49
1F VOLTAGE TO CHANGE TO L-L'
SYSTEM 4A
1A VERTICAL SYNC DELAY FOR TXT. 4B
69 SLICER CONTROL TTX ->
NIBBLE_UP = /NIBBLE_DOWN 4C
F0 CHANNEL SEARCH SPEED [UHF] 4D
F0 CHANNEL SEARCH SPEED [VHL] 4E
F0 CHANNEL SEARCH SPEED [VHH] 4F
AA HORIZONTAL SYNC DELAY 50
00 PASSWORD 1st DIGIT 51
00 PASSWORD 2nd DIGIT 52
00 PASSWORD 3rd DIGIT 53
00 PASSWORD 4th DIGIT 54
01 CHARACTER SET (LANGUAGE
TXT) 55
40 MAXIMUM TUNNING VOLTAGE
DECREASE DURING PROG.
CHANGE (IN CASE IT IS NOT
FOUND THE SYNCHRO)
56
VALUE DESCRIPTION ADDRESS
00 b0: HOTEL MODE: DEACTIVATE
THE TV PANEL FRONTAL KEY.
IT STARTS UP IN SCART
MODE
WHEN SSW SIGNAL IS GIVEN
b1: SPECIAL HOTEL MODE FOR
S.E.I.S. THE TIME CONSTANT
TO VCR MODE
b2: OPTION FOR DK_SYSTEM.
b3: AUTOINSTALL ON.
b4: COUNTRY SELECTION
MENU.
b5-b6: RGB DACs LEVEL.
b7: VPS_LOCK_SET
57
0F TIMING PACKET SEARCH, VPS. 58
20 VERTICAL SHIFT FOR 60HZ 59
BB ONE STEP DOWN WHEN THE
FIRST SYNCHRO LOOSING IS
PRODUCED
5A
15 UP MAXIMUM STEP No DURING
SEARCHING (

). 5B
00 CORRECTION VALUE OF V-SHIFT
IN ORDER TO BE INDEPENDENT
TO V-AMP BAND OFFSET SPEED
DURING SEARCHING
5C
15 AUTOMATIC PEAK RGB
REGULATION: PIC REGULATOR 5D
D2 BAND OFFSET SPEED DURING
SEARCHING (

)
NIBBLE_UP=/ NIBBLE_DOWN
5E
00 FREE 5F
10 TIMING PACKET SEARCH, 8/30. 60
---- RESERVED 61
a
FF
PIF/AGC Adjustment
1. B/G, L “AFT C”should not be adjusted. The value should be fixed to 0A.
2. B/G, L “AFT F”Adjustment
2.1. 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 dB/uV.
2.2. Enter into Service Mode.
2.3. Select parameter AFT F.
2.4. Push «CALL»button on R/C, see Page 43. «AFT OK»will appear in On Screen Display (OSD).
2.5. Switch set OFF and ON again, setting is now memorized.
3. L’“AFT C”should not be adjusted. The value should be fixed to 03.
4. L’“AFT FL”Adjustment
4.1. Connect the output of SSG (Standard Signal Generator) to the turner IF output terminal.
·SSG output 34.47MHz (CW) ± 5 KHz.
·SSG output level: approx. 90 dB/uV.
4.2. Enter into Service Mode.
4.3. Select parameter AFT FL.
4.4. Push «CALL»button on R/C, see Page 43. «AFT OK»will appear in OSD.
4.5. Switch set OFF and ON again, setting is now memorized.
5. RF-AGC Adjustment
5.1. Receive the “COLOUR Bar”Signal (Channel E-10). Signal strength: 53dB/uV
5.2. Enter into Service Mode.
5.3. Select parameter AGC.
5.4. Push “CALL”button on R/C, see Page 43. “BUS STOP”will appear in OSD.

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37GT-28FP
Screen Adjustment
1. Focus Adjustment
1.1. Apply mains voltage of 220V AC/50HZ to TV.
1.2. Receive Philips pattern signal to a level between 60 and 80 dB/uV.
1.3. Set contrast to 10/10, brightness to 5/10 and colour 0/10.
1.4. Adjust focus potentiometer to obtain maximum definition.
2.G2 Adjustment
2.1. Apply mains voltage of 220V AC/50HZ to TV.
2.2. Receive the “Cross Hatch”pattern signal to a level between 60 and 80 dB/uV.
2.3. Apply High Voltage Probe to Pin 8 of CRT socket
2.4. Adjust G2 potentiometer until obtaining 525V ±10%.
2.5. Check BKGD. If it is necessary adjust BKGD according to instructions detailed below.
Geometry Adjustment Procedure
1. Horizontal Shift
1.1. Receive Philips pattern signal.
1.2 Select H-SHFT with channel up or channel down buttons.
1.3. When volume up button is pressed, picture moves to the left.
1.4. When volume down button is pressed, picture moves to the right.
1.5. Adjust the horizontal location to obtain picture centering (Fig.2).
Fig. 2
2. Vertical Shift
2.1. Receive Philips pattern signal.
2.2. Select V-SHFT with channel up or channel down buttons.
2.3. When volume up button is pressed, picture moves up.
2.4. When volume down button is pressed, picture moves down.
2.5. Adjust the vertical location to obtain picture centering (Fig.3).
Fig. 3
3. Vertical Amplifier
3.1. Receive Philips pattern signal.
3.2. Select V-AMPL with channel up or channel down buttons.
3.3. When volume up button is pressed, vertical size of picture increases.
3.4. When volume down button is pressed, vertical size of picture decreases.
3.5. Adjust the vertical size to obtain picture overscan (Fig.4).
Fig. 4
The following adjustments are required when the Picture Tube or IC801 are replaced, or may be nec-
essary after adjustment of the G2 voltage.
Colour Adjustment (BKGD) Procedures
1. «B-GAIN», «G-GAIN»
1.1. Adjust G2.
1.2. Tune a grey scale pattern.
1.3. Adjust colour to minimum.
1.4. Fix R-GAIN value to 32.
1.5. Position colorimeter in the left point of Fig.5.
1.6. Using brightness and contrast buttons, select a luminance of »120 nits.
1.7. Operate again in Service Mode and select location B-GAIN and G-GAIN to obtain colour coordinates:
X = 0.290 ± 0.015
Y = 0.284 ± 0.015
6 5 4 3 2 1 0
Gain point
DC point
5.5. Push “GREEN”button on R/C (to exit Bus Stop Mode).
5.6. Switch set OFF and ON again, setting is now memorized.
Fig. 5

10
37GT-28FP
Procedure to Program Functions of Hotel Mode
Below listed can be found the procedure to carry out in the above TV Sets functions called HOTEL MODE as follows:
Consider that HOTEL MODE is implemented by means of HOTEL MODE 1. The HOTEL MODE 2 or HOTEL MODE 3
can be used at the same time than HOTEL MODE 1.
HOTEL 1 Blockade of tuning functions Restriction of sound
HOTEL 2 Blockade of tuning functions Start on SCART mode + SW when
SCART IS ACTIVE (Front Panel inactive)
HOTEL 3 Blockade of tuning functions VCR constant changed
Hotel 1 Mode: blockade of the TUNING function by modifying the value in 0A address of the NVM.
-This change besides blocking the tuning function, makes the TV always starts to operate in program 1.
Procedure:
A) Press the volume up or volume down buttons (RC) as far as the NVM address (green colour) displays “0A”location.
Check the NVM value (red colour) displays the NORMAL VALUE .
B)Pay Attention: Press the button 2 (RC) only once. The NORMAL VALUE has been changed to the HOTEL 1 MODE
VALUE now. If the button 2 (RC) is pressed again the NORMAL VALUE is recovered. For the same reason, if a wrong
button has been pressed, NORMAL VALUE can be recovered by pressing the same button again. See NVM table on
page 6.
Restriction of Sound Volume: by modifying the value in 0E address of the NVM.
Notes:
a) Before blocking the tuning function is necessary to memorise the programs according to the necessities of the destina-
tion hotel.
b) Since the Hotel Mode functions have been programmed the end users of the television won’t be able to tune different
channels neither to erase the existent ones.
1.8. Exit Service Mode and check colour coordinates «X»and «Y»at 20 and 120 nits. It may be necessary to repeat the
same procedure or readjust the cuts as show the be below one.
2. «CUT R», «CUT G»
2.1. Adjust G2, in the case that it has not been made previously.
2.2. Tune a grey scale pattern.
2.3. Adjust colour to minimum.
2.4. Position colorimeter in the right point of Fig.4.
2.5. Using brightness and contrast buttons, select a luminance of »20 nits.
2.6. Operate again in Service Mode and select location CUT-G and CUT-R to obtain colour coordinates:
X = 0.290 ± 0.015
Y = 0.284 ± 0.015
2.7. Exit Service Mode and check colour coordinates «X»and «Y»at 20 and 120 nits. It may be necessary to repeat
the same procedure or the previous one.
Cancel password (PIN)
The following process describes how to cancel actual password (PIN) when the customer forgets the code.
1. Press channel up or down to select the channel, wich you locked with input PIN number.
2. The TV picture will be blue and the key appear on screen.
3. Press and hold volume down on the TV and simultaneously press CHILD LOCK button (see Page.43) on the remote
control several times until the key disappears.