PAY ATTENTION TO THE OUTPUT VOLTAGE AND POWER WHEN CHANGING THE POWER BOARD

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 PAY ATTENTION TO THE OUTPUT VOLTAGE AND POWER WHEN CHANGING THE POWER BOARD

  We are Power Cord Manufacturers, here is a brief introduction to the precautions when changing the power board.

  The structure and output of boards used for different models are not the same. Therefore, when changing boards of different models, the output voltage and power should also be paid attention to when the installation location permits.

  In small-screen LCD color TVs, some use an external +12V power supply, some put the power supply board that outputs +12V voltage (some machines also have +5V voltage output) inside the machine, and some put the backlight driver and the circuit together. A board (often called IP board). This type of switching power supply circuit is relatively simple, and most faults can be repaired by replacing parts. If it is really difficult to repair, you can replace it with an external power adapter or switching power board with the same output voltage and slightly higher power.

  If it is an IP board, first cut off the AC220V input line of the original switch and the secondary voltage output terminal of the switching power supply, then connect the voltage output terminal of the newly purchased switching power supply board to the corresponding point, and then connect the on/standby control from the signal board. Line and AC220V incoming line can be. In the large-screen LCD color TV, the power supply of the backlight driver board is mostly +24V, which is the main source of the switching power supply.

  Large depends on the number of lamps. Under normal circumstances, the total power P can be estimated according to the power of a lamp tube of 8W, and then the maximum current of +24V can be obtained by dividing the total power P by 24V. In general, 32-inch screen is equipped with 16 lamps, 42-inch screen is equipped with 20 lamps, and 47-inch screen is equipped with 24~28 lamps. According to the above method, the maximum output current of +24V can be calculated as

  5A, 7A, 10A. [Tips] When estimating the load capacity of +24V voltage, it can be roughly calculated according to the ratio of "1A current with 3 lamps". Since most LCD color TV mainboards (including high-frequency head, audio and other circuits) need +12V and +5v power supply, this requires the power supply board to have +5v and +12V voltages in addition to the +24V voltage with sufficient output current. output. The maximum current of +5V and +12V should be considered from two aspects, - is the power consumption of the signal board itself, the current required by the +5V voltage is about

  800mA, the current required + 12V voltage is about 100mA; the second is the power consumption of powering the screen through the signal board (that is, the voltage on the upper screen), because the upper screen voltage of the large-screen LCD screen is mainly divided into 5V and 12V. , After actual measurement, if it is a screen powered by + 5V, the voltage and current on the screen is about 550mA; if it is a screen powered by + 12V, the voltage and current on the screen is about 300mA.

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