Tuesday, 17 August 2021

Xoceco 27 inch and 32 inch LCD TV – How to enter the service mode, service mode adjustments, SMPS (Power board) schematics software update procedure

 

Method for entering factory menu: Press MENU → [ -/--] → [9] → [1] → [8] one by one, then enter factory menu, press the SLEEP button to select adjustment page, exit factory menu to press the MENU button.

EEPROM initialization
Enter the first page of factory menu, select “EEPROM INITIALIZE” to be “on”, after turn off the unit, repeating turn on the unit is over.
White balance adjustment
Input PAL signal of 16-level gray-scale (TIMING969 PATTAN921) from VG848 to AV channel, enter user menu, set color to 0, APL to “off”, enter factory menu white balance adjustment page, select color temperature, fixed the GGAIN to 50H, adjust BGIAN and RGAIN to 400nits, then the color coordinate to 284, 299. Fixed the BOFFSET to 50H, adjust GOFFSET and ROFFSET to 5nits, then the color coordinate to 284, 299.
Select cool tint, adjust color coordinate to 270, 283.
Select warm tint, adjust color coordinate to 313, 329.
Performance Inspections
1 TV function
Enter the search menu → auto search, connect RF-TV terminal to the central signal source, check if there is station skipping.
2 AV/S input terminal
Input AV/S signal, check the picture and sound is normal
3 SCART terminal (note: check the SCART terminal, set display mode to AUTO)
3.1 Check SCART INPUT special function
3.1.1 SCART1 terminal function
a. After turn on the unit, connect the SCART1 to PM54200 signal generator, then the unit auto select to SCART1 mode.
b. SCART signal generator sends CVBS signal to the unit, check if the image and sound is normal.
It sends image format (16:9 and 4:3) to the unit, check if the unit auto identify is normal. Change SCART signal to RGB signal, check if the image and sound is normal, It sends image format (16:9 and 4:3) to the unit, check the unit auto identify is normal. Select the PIP mode, connect earphone cable, and check if the sound is normal.
3.1.2 SCART2 terminal function
a. After turn on the unit, connect the SCART2 to PM54200 signal generator, then the unit auto select to SCART2 AV mode.
b. SCART signal generator sends CVBS signal to the unit, check if the image and sound is normal.
It sends image format (16:9 and 4:3) to the unit, check if the unit auto identify is normal, and display the SCART2 AV. Change SCART signal to Y/C signal, select the SCART2 Y/C channel mode, check if the image and sound is normal, It sends image format (16:9 and 4:3) to the unit, check if the unit auto identify is normal. Select the PIP mode, connect earphone cable, and check if the sound is normal.
3.2 Check SCART OUTPUT special function
3.2.1 SCART1 terminal function
Input signal in the TV states, connect the SCART1 terminal to the TV. Change the TV program, check if output signal of SCART1 is TV signal, and the image and sound is normal, change the unit
channel, the CART1 output TV signal, it can not other signal.
3.2.2 SCART2 terminal function.

Input signal in the TV/AV/S states, connect the SCART2 terminal to the TV. Change the unit channel, check if output signal of SCART2 is current signal, and the image and sound is normal.
6.4 YPbPr/YPbPr terminal
Input the YUV signal (VG-848 signal generator), separate input YUV format signal of table 1, check if the image and sound is normal. If the image is deflection of the H-field, select auto sync correction of the SCREEN menu. If the image is slight disturb, adjust the FINE TUNE correction of the SCREEN menu. Open the PIP mode, connect the earphone, and check if the image and sound is normal.

VGA terminal
Input the VGA signal (VG-848 signal generator), separate input VGA format signal of table 1, check if the image and sound is normal. If the image is deflection of the H-field, select auto sync correction of the SCREEN menu. If the image is slight disturb, adjust the FINE TUNE correction of the SCREEN menu. Open the PIP mode, connect the earphone, and check if the image and sound is normal.
6.6 HDMI terminal
HDMI signal format receive the three high definition signal: 480P, 576P, 720P/50/60 Hz, 1080I/50/60 Hz, except for the table 2 signal. Check if the image (contain HDCP ON and OFF) and sound is normal. If the image is deflection of the H-field, select auto sync correction of the SCREEN menu.
Open the PIP mode, connect the earphone, and check if the image and sound is normal.






8.1 select TV channel

8.2 video menu, Mode: Standard, NR: Medium, APL:ON
8.3 sound menu, Volume: 20, Balance: 00, Equalizer: Custom, HP Volume: 20;
8.4 edit menu, Color System: Auto, Sound System: DK;
8.5 option menu, Default Zoom: Auto, Child Lock: Off, Menu Language: English, Country: UK,
WSS: OFF, Blue Screen: On.
Note: the 6.8.4 and 6.8.5 items should set according to clients require.

Method of software upgrading
1. Enter the software upgrading state of the TV
Method 1: press the VOL- button in the unit, turn on the main power switch, then the screen display black screen, but the indicator to blue.
Method 2: Enter factory menu, select the IIC-BUS OFF item.
2. Connection upgrading tools with upgrading port.
3. Dual- click IAPWriter logo, enter the upgrading states (if the PC and the IIC communication trouble, it can prompt.

4. Select the file menu load the software follow as:

5. Select WRITE DEVICE item of the device menu, till the right screen display “DONE”

Turn off the power , restart the unit.
Note: because of the software, it may be no-stabilization, the software can auto download and write.

NOTE: Do not shut the power off or turn the TV set on during the FLASH write. Otherwise it may lead to no way for flash to rewrite.

Working principle analysis of the unit
1. Analog signal flow
Antenna reception signal send to integrative tuner (contain HF and IF amplifier circuit), the tuner is controlled the command (SDA and SCL) of the MCU N301 (M16C), select appropriate channel to system switch, via HF amplifier and IF amplifier decode, output video signal of 2VPP and sound signal of 1VPP.
Sound signal (SCART1, 2 sound, AV sound, YPbPr, HDMI and D-SUB) via N581 HEF4052BT (sound diverter switch) to output signal, it send to N801(MPS3410 sound processing and volume control) switch of audio. Select right/left sound channel, their send to digital sound amplifier N803 (TPA3008) amplify, then send to speaker.
After output video signal of tuner, SCART1 video signal and RGB signal via matched resistance, the signal thought alone channel send to main decode IC(N101 SVP-EX52) video switch, A/D transition, digital decode, image scale and OSD superposition, then send to LVDS level drive for LCD screen.
AV, S-Video, SCART2 video and Y/C signal thought matched resistance, the signal send to the N506 video switch (SN74CBT3257CDR), via switching to selected signal (EX52_Y and EX52_C) to main decode IC (N101 SVP-EX52) video switch, A/D transition, digital decode, image scale and OSD superposition, then send to LVDS level drive for LCD screen.
D-sub and YPbPr signal thought matched resistance, the signal send to the N507 video switch (SN74CBT3257CDR), via switching to selected signal (EX52_YUV) to main decode IC (N101 SVP-EX52) video switch, A/D transition, digital decode, image scale and OSD superposition, then send to LVDS level drive for LCD screen.
2. Digital signal flow:
HDMI signal thought HDMI reception chip N405 (SiI9011HDMI with HDCP function), after receive, output digital format signal send to SVP-EX52 PIP channel thought image scale and OSD superposition, then send to LVDS level drive for LCD screen. The HDMI chip output audio digital format signal change to analog sound signal from N403 (CS4344 audio DA transfer chip), then N581 switched to N801 (MPS3410 sound processing and volume control).
3. TELETEXT function
This unit adopt main decode IC N101(SVP-EX52) of Trident company, it has TELETEXT decode function, after decoded, the teletext information in OSD display.

Sound processing IC (MSP3410)
Sound signal send to sound processing N801 MSP3410, and dual-circuit tuner has second SIF, it sends to N801 (stereo decode and auto volume control), N801 has audio channel switch, after switching in N581 (HEF4052BT), the audio input of GA/HDMI/YPbPr will be sent to N801 together with the audio signal of TV and AV to do the switching process. A way signal thought volume and high-low sound controlled, output the left and right audio send to digital audio amplifier N803 (TPA3008) amplify, then it send to speaker, other way signal output left-right audio send to earphone amplifier N805 (NJW1109), after audio control and power amplifier, it output to earphone socket. Other two ways signal output audio of TV out and AV out by SCART terminal of video board.

Xoceco 27 inch and 32 inch power board [SMPS] schematic diagram

L27W6 SMPS schematic

L32W5 SMPS schematic


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