"Samsung TV Mainboard Repair and Troubleshooting Guide" Do you want to learn learn Samsung tv mainboard repair and troubleshooting, do you want to learn the step by step guide of how to troubleshoot and repair all Samsung TV mainboard. Are you searching for Samsung TV mainboard repair and troubleshooting guide, samsung tv mainboard repair, samsung tv motherboard repair, samsung main board repair, samsung led tv motherboard repair or samsung TV troubleshooting. If yes, Infoguide Ng has brought a complete step by step guide of how to troubleshoot and repair all Samsung TV mainboard. This article detailed, step-by-step guide for troubleshooting and repairing a Samsung TV mainboard. This article explains that modern smart TV mainboard are more complex and less durable than older versions due to integrated features like Wi-Fi and smaller designs, often making them the second most expensive part to replace. This article emphasizes the importance of isolating the problem first using various testers before performing component-level repairs, outlining common faults such as "no power" issues and providing a sequential checking methodology that includes examining voltage lines, the CPU reset circuit, DDR RAM, and flash memory. Ultimately, the guide helps technicians save time by confirming if the issue lies with the mainboard or the power supply unit and suggests solutions ranging from component checking to firmware upgrades and BGA re-soldering.
NOTE -: Basic information and knowledge about troubleshooting a TV is essential before starting the repair.
The Nature of Modern TV Main Boards.
The TV main board is the second most expensive part of the television, particularly for smart TV mainboards. Compared to older LCD or LED TV versions, the latest smart TV main boards are less durable. This decreased durability is attributed to the new features added to the main board, such as network capabilities, Wi-Fi, Bluetooth, 3D, and others. The new design technology for the TV main board is more complex, requiring all new features to be fit onto the PCB board. Furthermore, some TV main boards now incorporate the power supply board and T-con section. This results in the main board size (PCB board) being smaller compared to older TV main boards. The latest model TVs are now experiencing many problems with the main board, with failure percentages nearly comparable to those of the TV power supply and backlight.
Troubleshooting and Isolating the Problem.
To save time, this article lists most main board problems, their checking methods, and solutions. The very first step for a repairer is isolating the TV problem.
Isolation tools and methods that are acceptable for identifying LCD or LED TV problems include:
- Power supply unit (PSU) self-test method.
- Backlight tester.
- TV main board output video tester.
- LVDS panel tester.
- Other helpful tools or testers.
Using these tools and methods helps the repairer isolate the TV problem easily, eliminating guesswork. Once the defective part or board is identified, the repairer can perform component-level repair on the board or opt to replace the defective board, especially if the customer urgently needs the TV.
Common Faults and Repair Ideas.
The following is a breakdown of common faults in LCD or LED TV main boards and corresponding repair ideas:
1. TV No Power (Indicator light off, no sound, no display)
For this issue, a repairer must first check if the PSU has output voltage.
A. Checking the Power Supply Unit (PSU):
- If there is totally no voltage output, disconnect the main board connector and check if the PSU standby voltage (3.3V or 5V) appears.
- If no standby voltage output is present, the problem lies with the PSU board, not the main board.
B. Checking the Main Board Power Signal:
- If the PSU has standby voltage (3.3V or 5V) but there is no power-on signal (Pwr On output signal) from the main board, it should be a main board problem.
- However, before confirming the main board is defective, ensure the front panel keypad and remote control are checked. If neither can power on the TV, the main board is confirmed defective.
C. Tracing the Defective Main Board
Components: For a confirmed defective main board (no power), tracing the issue involves several steps:
1. Standby Voltage Line Tracing: Check and trace corresponding components from the standby voltage line to the MCU or main chip. Modern TVs use main chips/CPUs with built-in MCUs.
2. LDO/DCC Circuits: Check the LDO IC, DCC IC, and regulator circuit loopholes first. Ensure the LDO or DCC circuit can output the normal, required voltages (5V, 3.3V, 2.5V, 1.8V, and 1.26V).
3. CPU Circuits: If the LDO/DCC voltages are normal, check the CPU reset circuit or crystal circuit.
4. Data Bus Lines: If the above are normal, check the SDA and SCL data bus lines on the main board. These lines usually connect to the CPU, flash memory, tuner, and audio IC. Ensure that components connected to these two lines are not shorted.
5. DDR RAM and Flash Memory: Next, check the DDR RAM and flash memory, particularly their voltage supply. The supply must be stable and normal.
- Check the reference voltage (Bref) of the DDR RAM.
- First generation: VCC 2.5V, Vref 1.25V.
- Second generation: VCC 1.8V, Bref 0.9V.
- Third generation: VCC 1.5V, Bref 0.75V.
- Most second and third-generation DDR RAM utilizes the BGA type package.
6. SMD Network Registers: Check the SMD network registers located between the DDR RAM and the CPU. If the register ohm values are out, open, or if there is leakage or an open circuit in their loopholes, the TV may not power on. A defective DDR RAM may also feel very hot on its surface.
7. Flash Memory (Firmware) Problem: Flash memory issues can involve the firmware or the memory IC itself being defective.
Smart TV firmware is typically split into two types:
- Bootloader (Portable firmware): Usually stored in the 25xx serial flash memory IC.
- Main Firmware: Usually stored in NAND flash or eMMC flash memory.
- If a bootloader problem is suspected, try upgrading the board firmware. A universal programmer can also be used to reprogram the bootloader flash memory with a known good firmware.
- Highly recommended: Always back up the original firmware before reading or writing to the flash memory IC.
- If reprogramming does not help, or if a firmware problem is found, it is highly recommended to replace the serial flash memory IC with a good one and write back the firmware.
- Note: Some main boards integrate the bootloader firmware into larger flash memory components, such as eMMC flash memory ICs.
8. Main Chip/CPU Defective: If all preceding methods fail, the main chip (CPU) is likely defective.
- Shortened CPU: Normally, the CPU surface will feel slightly warm in standby mode. If the CPU surface temperature increases suddenly or quickly while in standby mode, the CPU could be shortened.
- Dry Joint/Cold Soldering: If the TV is in standby mode, but the CPU shows no temperature difference before and after the main board powers on, the CPU may have a dry joint inside its BGA type pins. Dry joint or cold soldering points are common problems in TV mainboard CPUs currently.
- To test for a dry joint, try applying some pressure on the surface of the CPU, then power on the main board to see if there is any change. If a change is observed, attempt to re-solder, re-hot, or reball the BGA type CPU IC.
D. Final Check: Do not forget to check the front keypad and the IR (infrared) circuit corresponding components or loopholes connected to the MCU or main chip CPU for leakage or open circuit. Although this is a seldom-occurring issue, it can happen.
The detailed troubleshooting steps outlined here are like a highly specific checklist for an engineer inspecting a complex machine: you move systematically from the general power source, down to the main processor's power regulators, communication lines, memory chips, and finally, the processor itself, ensuring every functional stage is checked before concluding that the heart of the system is the issue.
I believe this step by step guide will help resolve mainboard problems on all Samsung LED or LCD TV.
Here's a video that explain Samsung TV Mainboard Repair and Troubleshooting.
