Continued: Re-discussing the replacement method and attention points of LCD TV backlight tube with real static pictures - News - Global IC Trade Starts Here Free Join

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This article continues the discussion on LCD TV backlight compatibility and replacement, focusing on the "Static Picture" scenario. As we all know, LCD TVs use two main types of backlights: CCFL (Cold Cathode Fluorescent Lamp) and EEFL (External Electrode Fluorescent Lamp), each requiring different driver boards for operation. The author has broken down the topic into three key areas to provide a comprehensive understanding.

A. Types of Backlight High Voltage Boards (Light Boards):

• <1> 24V power supply type with single transformer output drive board.
• <2> 24V power supply type with multiple transformer output drive board.
• <3> High-voltage integrated power supply type with single transformer output drive board.
• <4> High-voltage integrated power supply type with multiple transformer output drive board.

B. Compatibility and Replacement Methods Between Backlight Tubes and Driver Boards:

• <1> Single transformer high-voltage output board (for EEFL tubes) is compatible with high-voltage integrated single transformer output drive boards.
• <2> Multiple transformer high-voltage output boards (for CCFL tubes) are compatible with inline and bayonet-style high-voltage boards.
• <3> High-voltage integrated single transformer superimposed multiple transformer output drive boards are compatible with multi-transformer high-voltage output boards.
• <4> High-voltage integrated single transformer superimposed multiple transformer output drive boards (for loop ungrounded CCFL tubes) are compatible with multi-transformer high-voltage output boards.
• <5> Double-board inline and bayonet high-voltage boards (for CCFL tubes) are compatible with multi-transformer high-voltage output boards.
• <6> Inline and bayonet high-voltage boards (for CCFL tubes) are compatible with multi-transformer high-voltage output boards.
• <7> Single transformer high-voltage output boards (for CCFL tubes with capacitive coupling) are compatible with single transformer high-voltage output boards.

C. Key Points in Replacing Backlight Tubes and Driver Boards:

It’s important to note that while EEFL tubes typically use a single transformer (around 1000V), CCFL tubes require multiple transformers (around 1500V). This means their driving circuits differ significantly. However, under certain conditions, it may still be possible to use a single transformer to drive a CCFL lamp, as demonstrated in practice. This shows that theoretical limitations can sometimes be overcome through real-world experience.

Additionally, when replacing lamps, always pay attention to the polarity—usually marked as “hot end” (high voltage) or “cold end” (low voltage). Some models may have markings, while others don’t. Be cautious about the connection order, as reversing the polarity could trigger a high-voltage protection mechanism and cause the screen to go black suddenly.

When replacing a backlight tube, consider its length, diameter, and color temperature. It's also essential to match the new lamp with the correct driver board and circuit configuration. While this guide covers most common cases, always double-check specifications before making any replacements.

The images provided illustrate various types of backlight tubes and their corresponding driver boards. These examples cover a wide range of LCD TV models and configurations. The content here is based on personal experience and practical insights, not official documentation. It is intended for reference only and does not represent any specific opinion or position.