Thursday, January 28, 2016

LENOVO L2062bW Wide LCD Monitor Service mode - Software update - DDC writing - Power supply circuit - LD7552BPS – LCD monitor repair and service – Manual service

Category: LCD Monitor Repair and Service 

Contents of this article 

  • How to access service modes
  • DDC Program writing
  • Power supply schematic 


LENOVO L2062bW 

SERVICE MODE
Factory mode adjustment
After replacing the Main board and the Panel, Check for enter the Factory mode ,then re-writing DDC is necessary.
Press MENU button and hold,reinsert the Power cord , then ,press MENU , the monitor will may enter Factory OSD Menu. Then Press 
Factory OSD Menu will appear in the screen.
In normal user mode, open the menu to restore factory default values
Maintenance
Maintainability Requirement
1. Voltmeter. & digital multimeter
2. Oscilloscope.
3. Pattern Generator.
4. DDC Tool with Compatible Computer.
5. Alignment Tool.
6. LCD Color Analyzer.
7. Service Manual.
8. User Manual.
9. repair tools etc
Disassembly SOP
1. Precaution
Please read the precautions as follows to prevent any damages to the LCD Monitor
Make sure all power connection is removed. Be sure that the LCD Monitor is in power off status.
1.Prepare soft cloth and sponge as working platform to place LCD monitor horizontally.
2. Hold LCD by the side carefully and DON’T touch or press panel directly.
3. appropriate tools
select the appropriate tools for disassembly and re-assembly.
Phillips screwdriver
spacer screwdriver
C/D Disassembly Tool
Gloves or soft cloth
Software update step
After replacing the Main board and the Panel, Check if white-balance is within the specs ,then re-writing DDC is necessary.
Software information
U401
056G1125191
IC RTD2122L-LF LQFP-48
SMTCR-U401
100GLRSA006B11
L2021W_SEC_LTM200KT03_M20_
RTD2545LH_100729_v0.01_Eng.H00
U501
056G 562201
IC RTD2545LH-GR QFN-48

CBPCARJG1J1
G3327-1-X-X-2-090407 FOR L2021WA
Step1 Connection
1. Connect USB cable to the PC USB port and the ISP tool,
715GT089-B);
2. Will be the Monitor VGA cable to connect ISP tool

3. ISP tool card connection 
Step2 Installing driver software
1.To install the USB driver software, mstar ISP Driver3-DB07-6-XP-driver
Step3 Run software “RTD Tool V1.7 version”
1.selected ISP,-àRTD2122 ,as shown in, Press the icon to select,Note save HDCP key:
2.selcted “Page Select”
3.Click “64K”,selcted software files
In this way, Automatic Identification space size,Next ,selected “Externd True Size”
4.Click Program icon ,Programming started,After Programming, Appear PASS.
Writing DDC program step
1. Prepared the PC with Windows XP system, DDC recording device (12V)
2. Connect the DDC recording device and the PC through PC parallel port
3. setup “Port95nt” driver program to PC ,
4. select relevant program and run it,
5, Press “LoadFile”, select EDID -model of product, and select input port;
6. key in SN,and other informatiom, key-press “Pragram” button;
LD7552 PWM Controller
Description
The LD7552 is a low cost, low startup current, current mode PWM controller with green-mode power-saving operation. The integrated functions such as the leading-edge blanking of the current sensing, internal slope compensation and the small package provide the users a high efficiency, minimum external component counts, and low cost solution for AC/DC power applications.
The special green-mode control does not only achieve low power consumption but also offer a non-audible-noise operation when the LD7552 operates under light load or no load condition.
The LD7552 is designed for the switching adaptor with 30W> 60W output. The LD7552 is offered in both SOP-8 and DIP-8 package.
PIN CONFIGURATION
1 GND - Ground
2 COMP - Voltage feedback pin (same as the COMP pin in UC384X), By connecting a photo-coupler to close the control loop and achieve the regulation.
3 VCC  - Supply voltage pin
4 RT - This pin is to program the switching frequency. By connecting a resistor to ground to set the switching frequency.
5 NC - Unconnected pin
6 CS - Current sense pin, connect to sense the MOSFET current
7 VCC - Supply voltage pin
8 OUT - Gate drive output to drive the external MOSFET
POWER SUPPLY SCHEMATIC 
CLICK ON THE IMAGES TO ZOOM IN