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

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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.

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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

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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)
}
}
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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