How to fix LCD TV with No video but Blue Screen and Vertical White Bars
Brand: Hisense TLM-3233D LCD TV
Chassis: MST9
Symptom: No Display but Blue Screen with Two Vertical White Bars
When power on this lcd tv, the screen show no display but blue screen with two vertical white bars. The two vertical white bars will flash but no any content inside. The LCD TV can hear the sound and remote control to change channel properly. Try other video signals input like AV and PC also same results. Even try to call out the OSD menu also same problem too.
Since the LCD TV cannot show the OSD menu and the TV got sound and change channel properly, so that the mainboard is normal. After observation this lcd tv, found that the problem could be in the T-CON board or LCD panel.
Check LVDS and FPC cables, they are show as normal, then check the T-CON board voltages. All voltages in T-CON board are ok, so that i will suspect the T-CON board mainchip (N39) or their memory chip (N31) defective. I got the junk T-CON board with same part number, but their DC-DC chip was burnt. So the mainchip and memory IC can be use.
Because of the N39 (CM2681) have many pins and the memory IC N31 (24LC128) only have 8 pins, so that I choose to replace the N31 first. After replace the N31, I try to power on the TV, and it was show display perfectly!
Since this N31 is a memory IC, does that mean IC itself damage or just the firmware corrupt and caused this problem happen? To find out this answer, I use my programmer to copy the working memory IC firmware and write it into the original memory IC. Do you guess what has happen? Yes, the LCD TV working perfectly too! So the problem solved and it was causing by the firmware corrupted.
Conclusion: The T-CON board memory chip or their firmware corrupt also can cause the screen problem. So that we need to save their firmware and must prepare some junk boards of T-con board, mainboard and inverter board for future use.

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Home » Blog » How to Repair LG 32LB9R-TB LCD TV Random Auto Shutdown
How to Repair LG 32LB9R-TB LCD TV Random Auto Shutdown
Posted by System Administrator in LCD TVs on May 10, 2014 . 0 Comments.

This is an LG 32LB9R-TB LCD TV. The problem was it will auto shutdown after 5 minutes or 30 minutes, sometime after 1 hours then power shutdown. When try to press again the TV power on switch, the Tv will directly shutdown again or after few seconds.
When using table fan to blow the Power Supply board (PSU), and using a piece of card board to block the wind blow to mainboard. The TV can last 2 hours still working properly. After that the table fan change to blow the mainboard and the card board block the PSU. The TV was shutdown just after about 8 minutes! This power supply board is an IP board, the part number is: EAY38637401. Even change the table fan blow the PSU, the TV can last longer to working!
With this method, we know that the problem was inside the power supply board. So I can replace a working power supply board to solve this TV problem. But I want to repair it in components level and want to find out which component is causing the symptom like this.
Since we know that the problem was inside the PSU board, so we can concentrate to testing or troubleshoot this board. Using the hot hair dryer to blow the PSU board to find out which section is sensitive with the heat blow and shutdown the TV. Before that, checking their ERR pin and it was located in PSU board connector. Where the ERR pin features are to detect any high temperature, abnormal current and voltage activity occurs and the mainboard CPU will shutdown the TV to prevent any serious damage in it. I found that their ERR pin voltage was starting (when power on the TV) from 4.68V slowly drop to 3.19V. When the ERR pin voltage drop to 3.28V the TV will shutdown. That’s mean when ERR pin voltage drop to 3.28V, the TV will in protection mode (TV automatic shutdown) .So we need to know which section is causing this voltage drop and causing the TV in protection mode.
This PSU board is an IP board, so their inverter section was built-in into the board. Inside this PSU board, it has PFC section, PWM section, Voltage output section and the High Voltage section (inverter). So using the hot hair dryer to blow to the PSU board carefully and found that the inverter section was the culprit! After that using soldering iron and freeze/Coolant to use interchangeably to testing their small components inside the inverter section.
Finally found the Q311 (1A) smd NPN transistor was defective and it is nearby the U302 (LM393). Replaced it with a H1A (2N3904) smd NPN transistor and the TV working properly now.
After changed the Q311, the ERR pin voltage is about 3.53V. Even this TV working about 9 hours, their ERR pin voltage still stable and it’s about 3.56V.
LCD TV panel ribbons causing vertical lines on one half of screen display, sometimes these lines appears and disappear from the screen. This is a very common problem in LCD/LED TV. Manufacturers of LCD/LED tv are using more cheaper product especially at the budget end, so these devices are meant to expire after the date of warranty.
In this case sticky factory glue which was placed under the LCD panel ribbons begins to fade out with time, and the more it loses and wear out it the ribbon cable begins cause contact image problem, which is the vertical line running across one side of the screen.
Now opening up the TV cover and then remove the metal frame covering the LCD panel, there you will see the ribbon cable connected to the LCD screen at the top of the TV,go over to the affected area and apply a little pressure you will observe the screen picture getting a clearer picture but you release it the lines appears again on the screen.
Brand: Hisense TLM-3233D LCD TV
Chassis: MST9
Symptom: No Display but Blue Screen with Two Vertical White Bars
When power on this lcd tv, the screen show no display but blue screen with two vertical white bars. The two vertical white bars will flash but no any content inside. The LCD TV can hear the sound and remote control to change channel properly. Try other video signals input like AV and PC also same results. Even try to call out the OSD menu also same problem too.
Since the LCD TV cannot show the OSD menu and the TV got sound and change channel properly, so that the mainboard is normal. After observation this lcd tv, found that the problem could be in the T-CON board or LCD panel.
Check LVDS and FPC cables, they are show as normal, then check the T-CON board voltages. All voltages in T-CON board are ok, so that i will suspect the T-CON board mainchip (N39) or their memory chip (N31) defective. I got the junk T-CON board with same part number, but their DC-DC chip was burnt. So the mainchip and memory IC can be use.
Because of the N39 (CM2681) have many pins and the memory IC N31 (24LC128) only have 8 pins, so that I choose to replace the N31 first. After replace the N31, I try to power on the TV, and it was show display perfectly!
Since this N31 is a memory IC, does that mean IC itself damage or just the firmware corrupt and caused this problem happen? To find out this answer, I use my programmer to copy the working memory IC firmware and write it into the original memory IC. Do you guess what has happen? Yes, the LCD TV working perfectly too! So the problem solved and it was causing by the firmware corrupted.
Conclusion: The T-CON board memory chip or their firmware corrupt also can cause the screen problem. So that we need to save their firmware and must prepare some junk boards of T-con board, mainboard and inverter board for future use.

MENUAccessories And Tools - General UseBGA and IC chipsBGA Rework StationsCNC EquipmentParts and SparesReballing - Tools And MaterialsRework AcessoriesRework EquipmentTest Equipment
Home » Blog » How to Repair LG 32LB9R-TB LCD TV Random Auto Shutdown
How to Repair LG 32LB9R-TB LCD TV Random Auto Shutdown
Posted by System Administrator in LCD TVs on May 10, 2014 . 0 Comments.

This is an LG 32LB9R-TB LCD TV. The problem was it will auto shutdown after 5 minutes or 30 minutes, sometime after 1 hours then power shutdown. When try to press again the TV power on switch, the Tv will directly shutdown again or after few seconds.
When using table fan to blow the Power Supply board (PSU), and using a piece of card board to block the wind blow to mainboard. The TV can last 2 hours still working properly. After that the table fan change to blow the mainboard and the card board block the PSU. The TV was shutdown just after about 8 minutes! This power supply board is an IP board, the part number is: EAY38637401. Even change the table fan blow the PSU, the TV can last longer to working!
With this method, we know that the problem was inside the power supply board. So I can replace a working power supply board to solve this TV problem. But I want to repair it in components level and want to find out which component is causing the symptom like this.
Since we know that the problem was inside the PSU board, so we can concentrate to testing or troubleshoot this board. Using the hot hair dryer to blow the PSU board to find out which section is sensitive with the heat blow and shutdown the TV. Before that, checking their ERR pin and it was located in PSU board connector. Where the ERR pin features are to detect any high temperature, abnormal current and voltage activity occurs and the mainboard CPU will shutdown the TV to prevent any serious damage in it. I found that their ERR pin voltage was starting (when power on the TV) from 4.68V slowly drop to 3.19V. When the ERR pin voltage drop to 3.28V the TV will shutdown. That’s mean when ERR pin voltage drop to 3.28V, the TV will in protection mode (TV automatic shutdown) .So we need to know which section is causing this voltage drop and causing the TV in protection mode.
This PSU board is an IP board, so their inverter section was built-in into the board. Inside this PSU board, it has PFC section, PWM section, Voltage output section and the High Voltage section (inverter). So using the hot hair dryer to blow to the PSU board carefully and found that the inverter section was the culprit! After that using soldering iron and freeze/Coolant to use interchangeably to testing their small components inside the inverter section.
Finally found the Q311 (1A) smd NPN transistor was defective and it is nearby the U302 (LM393). Replaced it with a H1A (2N3904) smd NPN transistor and the TV working properly now.
After changed the Q311, the ERR pin voltage is about 3.53V. Even this TV working about 9 hours, their ERR pin voltage still stable and it’s about 3.56V.
LCD TV panel ribbons causing vertical lines on one half of screen display, sometimes these lines appears and disappear from the screen. This is a very common problem in LCD/LED TV. Manufacturers of LCD/LED tv are using more cheaper product especially at the budget end, so these devices are meant to expire after the date of warranty.
In this case sticky factory glue which was placed under the LCD panel ribbons begins to fade out with time, and the more it loses and wear out it the ribbon cable begins cause contact image problem, which is the vertical line running across one side of the screen.
Now opening up the TV cover and then remove the metal frame covering the LCD panel, there you will see the ribbon cable connected to the LCD screen at the top of the TV,go over to the affected area and apply a little pressure you will observe the screen picture getting a clearer picture but you release it the lines appears again on the screen.
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