Read Sharp 37GQ-20 (serv.man3) Service Manual online
1
37GQ-20H
SERVICE MANUAL
SHARP CORPORATION
CONTENTS
PAL SYSTEM COLOUR TELEVISION
SEJB37GQ20H02
SQUAD
CHASSIS
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.
regulations in some countries) the set should restored
to its original condition and only parts identical to
those specified should be used.
MODEL
37GQ-20H
Issued: 9th June ‘00
ELECTRICAL SPECIFICATION.......................2
IMPORTANT SERVICE NOTES.......................3
SERVICE ADJUSTEMENTS.............................4
PRINTED WIRING BOARDS...........................11
SERVICE ADJUSTEMENTS.............................4
PRINTED WIRING BOARDS...........................11
SCHEMATIC DIAGRAM, WAVE FORMS..... .13
PART LIST.......................................................18
TROUBLESHOOTING TABLES......................22
2
37GQ-20H
ELECTRICAL SPECIFICATIONS
•
Power Input .......................220V-240 Volts AC 50Hz
•
Power Consumption
•
Audio Power Output Rating .....................2W (MPO)
Speaker............................32
Ω
2W, 8cm Round, 1pc
Normal Operating...................................30W
Stand-by Operating................................7.5W
(Method IEC60107)
(Method IEC60107)
•
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 8950 degree K-20 MPCD screen
temperature should not exceed 15% of its original value.
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
WARNING
The chassis in this receiver is partially live, always 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.
servicing this chassis.
To prevent electric shock, do not remove cover. No user-serviceable parts inside. Refer
servicing to qualified service personnel.
Convergence.........................Self Converging System
Focus....................................Bi-Potencial Electrostatic
Sweep Deflection...........................................Magnetic
Specifictions are subject to change without prior notice.
•
Aerial Input Impedance
VHF/UHF...........................75 ohm Unbalanced
•
Tuning Ranges ............471.25MHz thru 855.25 MHz
(CH21-CH69)
•
Picture Intermediate Frecuencie.....
.........38.9MHz
•
Sound Carrier Trap
.............................32.9MHz
•
Adjacent Sound Carrier Trap
................40.9MHz
•
Adjacent Picture Carrier Trap
...............30.9MHz
3
37GQ-20H
IMPORTANT SERVICE NOTES
SERVICING OF HIGH VOLTAGE SYSTEM AND PICTURE TUBE
Maintenance and repair of this receiver should be done by qualified service personnel only.
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).
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.
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:
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
1000
1000
µΑ)
for the set.
2. To keep the set in a normal operation, be sure to make it function on 22.4KV
±
1.5KV (at beam
800
µΑ)
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.
result of the repair.
3. Do not substitute a picture tube with unauthorized types and/or brands which may cause excess
X-Ray radiation.
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.
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.
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.
4
37GQ-20H
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.
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.
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.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
n.
h.
i.
j.
k.
l.
m.
n.
SERVICE
NVM
AGC GAIN
AGC STR
PLL
PAL
NVM
AGC GAIN
AGC STR
PLL
PAL
AUTO
B-GAIN
G-GAIN
G-DC
R-GAIN
R-DC
HOR POS
VERT POS
VERT AM
G-GAIN
G-DC
R-GAIN
R-DC
HOR POS
VERT POS
VERT AM
Displayed
on screen
on screen
Hexadecimal /
Decim. Range
Function
00
∼
03H
00
∼
63H
S, L, VL, N
4-43, 3-58,
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
Indicates operative Service Mode.
Access to NVM memory
Auto Gain Control
Auto Gain Starting Point
Line PLL time constant
Colour system.
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
Vertical Position shift
Vertical Amplitude shift
Green Gain
Green Cut
Red Gain
Red Cut
Horizontal Position shift
Vertical Position shift
Vertical Amplitude shift
6. For « a » Selection:
NVM storage location settings variants.
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.
