Xoceco TQ2426 Schematic

COLOR TELEVISION
TQ2426
CONTENTS
Safety precautions………………………………………………………………………..…
Alignment instructions …………………………….…….………………………..…….…
Block diagram…………………………………..……………………….………….………
IC block diagram………………………………………………………………………..……
Wiring diagram ……………………………………………………………..……………...
Troubleshooting………………………………………………………………………..……
Schematic diagram …………………………………………………………………….…..
APPENDIX-A: Main assembly list
APPENDIX-B: Exploded view
1
2
8
9
10
15
16
18
Note: This service manual is only for professional service personnel’s reference. Before
servicing the unit, please read the following items carefully.
Safety instruction
1. X-RAY radiation precaution
1.1 Excessive voltage will cause harmful X-ray. To avoid this radiation hazard, the high voltage should
fall within the limitation. The appliance works at AC 120V, 60Hz. The high voltage of zero beam current
(brightness is min) should be within 30kV on condition that the main power voltage is 110V(13”, 20”),
130V(24”) and 135V(37”). And it should not exceed 33kV in any condition.
When servicing, please refer to the HIGH VOLTAGE CHECK procedure this service manual before
check the high voltage and the high voltage meter should be reliable and accurate.
* Keep the main power voltage at 110V(13”, 20”), 130V(24”) and 135V(37”) when checking the high
voltage.
1.2 The primary source of X-RAY RADIATION is the CRT. The CRT of this TV set have gotten the
approval of safety authentication inspection. The replacement CRT should be exactly the same type and
specification CRT which has gotten a similar safety approval, and check the high voltage according to
the HIGH VOLTAGE CHECK procedure.
2. Safety precaution
a. Since the power supply circuit of this receiver is directly connected to the AC power line, an isolation
transformer is necessary during dynamic service to avoid possible shock hazard.
b. Always discharge the graphite layer conductor when moving the CRT.
c. Disconnect the power cord before replacing parts.
d. When replacing high-power resistor, keep the resistor 10 mm away from the circuit board.
3. Component safety precaution
Many electrical and mechanical parts in the chassis have special safety-related characteristics. These
characteristics are often passed unnoticed by a visual inspection. Replacement parts which have these
special safety characteristics are identified in this manual and its supplement electrical components
having such features are shaded or marked by on the schematic diagram and the parts list. Before
replacing any of these components, read the parts list in this manual carefully. The use of substitute
replacement parts which do not have the same characteristic as specified in the parts list may create
shock, fire, X-RAY RADIATION or other hazards.
General instruction
1. Copy the standard model data to let EEPROM (N101)of the chassis have those data before placing
it on the unit, do “factory adjustment” if necessary. If use a blank EEPROM directly, you should preset IIC
data and then do other common adjustment.
2.The adjustment should be done under following circumstances without additional instruction
a) Alternating current 120V/60Hz
b) Preheat at least 30 min
3.The unit has auto degaussing circuit, the auto degaussing process can be finished within 1s when
the main power. Only when turn on the unit at least 30min after last time turn off TV does the auto
1
degaussing circuit work.
4. If the CRT with magnetism affects color purity and convergence, when the auto degaussing eraser.
if the color purity and convergence are still not very good, then corresponding adjustment should be
done. Refer to picture tube adjustment method for adjustment.
Alignment instruction
1. Debugging item
a) VIF adjustment
b) S-TRAP adjustment
c) H VCO adjustment
d) OSD adjustment
e) B+ voltage adjustment
f) RF AGC voltage adjustment
g) Focus adjustment
h) Screen-grid voltage white balance adjustment
i) Field, line scan center adjustment
j) Filed, line amplitude adjustment
k) Raster adjustment
2. Alignment flow
2
E2PROM copy
VIF adjustment
S-TRAP adjustment
H VCO adjustment
OSD adjustment
B+ adjustment
RF AGC adjustment
Focus adjustment
Screen-grid voltage white
balance adjustment
Scan amplitude, center and
raster adjustment
Check
Fig-1 alignment flow
High voltage check
X-ray protect check
Filament voltage check
Picture and sound check
Sub brightness check
White balance check
Color Purity, convergence check
AV terminal check
The unit and remote control
3
3. Factory menu adjustment (FACTORY MENU PAGE)
3.1 VIF adjustment
Receive a NTSC signal at will, enter factory menu VCJ ADJ, select VIF VCO, press “VOL+/_”, then
display “END” and it means IC has adjust IF to 45.75MHz automatically.
3.2 S-TRAP adjustment
Receive a NTSC signal at will, enter factory menu VCJ ADJ, select S-TRAP, press “ VOL+/_”, then IC will
adjust S-TRAP to the best situation.
3.3 H VCO adjustment
Receive a NTSC signal at will, enter factory menu RASTER ADJ, select H VCO ADJ, press “ VOL+/_”,
then IC will auto adjust H VCO to the best situation.
3.4 OSD adjustment
Receive NTSC signal, check the OSD, if OSD is not at the center of the screen, you can adjust ”110:
OSD H-POS” of the last page of SERVICE MENU.
3.5 B+ voltage adjustment
a) Make sure that the power is AC 120V/60Hz
b) Connect B+ point with a digital voltmeter, receive A-7 signal, set the picture to “standard”, the
value of B+ voltage should be 110 V ±0.5 V(13”, 20”), 130V ±0.5 V(24”), 135V±0.5 V(27”).
3.6 RF AGC adjustment
RF AGC is auto adjusted by the turner.
3.7 Focus adjustment
a) Receive A-12 PHILIPS signal, set user control to “standard”.
b) Adjust focus electrode potentiometer on FBT to optimize focus of screen.
3.8 Screen-grid voltage and white balance adjustment
a) Receive A-7 signal, set user control to “user” and the brightness, contrast and color are zero.
b) Adjust potentiometer of SCREEN till the top side seven lattices slightly light up.
c) White balance adjustment of analog TV channel and AV channel.
Input erect 10-gray scale signal of VP403, at AV channel, set user control to “standard”. Adjust
the center of the right third level of dark balance and the center of the left second level of bright
balance. Enter CRT ADJ of factory menu, fixed CUT G(150), adjust CUT R, CUT B, DRV-R,
DRV-B till the white balance is normal basically.
d) White balance adjustment of COMPONENT channel and digital TV channel.
Input erect 10-gray scale signal of VP403, at COMPINENT channel, set user control to
“standard”. Adjust the center of the right third level of dark balance and the center of the left
second level of bright balance. Enter CRT ADJ of factory menu, fixed CUT G YUV(150), adjust
CUT R YUV, CUT B YUV, DRV-R YUV, DRV-B YUV till the white balance is normal basically.
Then enter CR PED, CB PED to adjust the dark balance of COMPONET channel again, in
order to let it more accurate.
Enter digital TV channel and check if the balance is up to the mustard, if not, adjust CUT R DTV,
CUT G DTV, CUT B DTV. The adjust method of DTV R PED, DTV B PED is as same as it of
COMPONENT channel
3.9 line, field center adjustment
Receive CENTER CROSS 100IRE signal of VP403, set user control to “standard” of AV channel, enter
RASTER ADJ item, adjust field center V-POS, line center H-POS, let the center of picture coincide with
center of screen.
3.10 line, field amplitude adjustment
4
a) field amplitude adjustment
Receive PERCENT OVERSCAN signal of VP403, set user control to “standard” of AV channel, enter
RASTER ADJ item, adjust field amplitude V-SIZE, let the vertical reproduction ratio of picture acceptable
5%.
b) line amplitude adjustment
receive PERCENT OVERSCAM single of VP403, set user control to “standard” of AV channel.
13” and 20”: adjust B+ potentiometer RP502, let the line reproduction ratio of picture acceptable 5%.
20”, 24” and 27”: enter RASTER ADJ item, adjust line amplitude H-SIZE, let the line reproduction ratio of
picture acceptable 5%.
3.11 line, field linearity and geometry adjustment
receive CROSSHATCH single of VP403, set user control to “standard” of AV channel.if the linearity and
geometry are not satisfied, you may adjust the following items of RASTER ADJ:
Corner PARA
Trape VS-CORE V-LIN
Note: CORNER, PATR, TRAPE need not adjust at 13” and 20”.
4. Checking point
4.1 High voltage check
Connect High Voltage meter between CRT second anode and GND.
1) Receive A7 signal, set user control to “STANDARD”, measure the high voltage value, the reading
should be the value below: 13”: 22 kV±1 kV 20”: 25.5 kV±1 kV
24”: 27 kV±1 kV 27”: 29kV±1 kV
2) Set the brightness and contrast to minimum (zero beam current), measure the high voltage, the
reading should not exceed 33kV.
4.2 CRT filament voltage check
Receive A7 signal, set picture to “STANDARD”, use effective voltage meter to measure CRT filament voltage, the reading should be (6.3±0.3) Vrms
4.3 X-ray protection check
1) Receive A7 signal, set user control to “vivid”.
2) 13”, 20”, 24”: Short circuit R309 (TP302, TP303), X-Ray protection circuit should function.
27”: press S301, X-Ray protection circuit should function.
4.4 Picture and sound check
1) Receive standard TV signal, include NTSC and ATSC.
2) Use picture control buttons to check color, contrast, brightness, sharpness, tint’s function.
3) Use sound control buttons to check volume control function.
4.5 Sub-brightness, sub-contrast check
1) sub-brightness check
Receive full-screen 8IRE signal of VP403, set user control to “standard” and check if it is satisfied (for
example: BESTBUY require brightness of 7.5IRE BLACK 0.20 ft.L), if not, enter PICTURE ADJ item.
AV channel: ATV BRIGHT
COMPONENT channel: YUV BRIGHT
DTV channel: DTV BRIGHT
Fine adjust the items to let it be satisfied (suggest 0.15 ft.L BLACK brightness ≤0.20 ft.L).
2) sub-contrast check
Receive window 100IRE signal of VP403, set user control to “standard” and check if it is satisfied (for
5
example: BESTBUY require brightness of window 100IRE70 ft.L), if not, enter PICTURE ADJ item.
AV channel: ATV CONTRAST
COMPONENT channel: YUV CONTRAST
DTV channel: DTV CONTRAST
Fine adjust the items to let it be satisfied.
4.6 Color purity and convergence check (in normal way)
4.7 AV/S terminals video and sound IN/OUT check
4.8 COMPONENT channel video and sound IN check.
4.8 Other buttons on the TV set and remote controller function check.
5 Ex-factory setting
Enter factory menu SHIPMENT OFF, press right button to let OFF turn to ON, then exit the factory menu.
5.1 picture menu
CONTRAST 45
BRIGHTNESS 35
COLOR 45
TITN 0
SHARPNESS 30
PICTURE MODE STANDARD
MORE
5.2 Volulme: 30
5.3 Language: English
5.4 TV mode: channel 2
6 Factory menu
6.1 enter factory menu method
1) Press factory button to enter factory menu.
2) Press CH+ or CH- to select sub-menu and VOL+ or VOL- to enter.
3) Press MENU to exit.
6.2 the content of factory menu see table 1
table 1 factory menu
FACTORY MENU
01. VIF VCO VIF VCO auto regulation
1: VCJ ADJ
2: RASTER ADJ
02. RF DELAY TUNER AGC adjustment
03. S-TRAP S-TRAP auto regulation
06. H VCO H VCO auto regulation
07. V-POS Field center adjustment
08. V-SIZE Field amplitude adjustment
09. V-LIN Field linearity adjustment
10. VS-CORE Corner adjustment
6
Loading...
+ 16 hidden pages