半桥 power main switch 三极线卡边发热 is serious, high probability of static parameter misalignment (β value deviation＞±15% or VCE(sat) difference＞0.15V) will cause current distribution misalignment, must be stopped for inspection and replacement;同时还需要验证驱动信号一致性、驱动变压器匝数比、冷却接触可靠性。

时间过长或current distribution 失衡，must immediately stop the machine to check，otherwise it will cause hot loss of control. Confirm whether it is half bridge topology

Turn on the power of the shell，目视主电影： Find three transformers arranged in a straight line (卡大两小), Among them, the small transformer in the middle is the driving transformer, and the two sides are the auxiliary power transformer and the main transformer. >

Note: Generally, there is only one main transformer, no isolation capacitor, and the main filter capacitor is a single 400V or higher specification, a mistake will lead to the subsequent detection of the wrong direction. Static parameter measurement and matching filter

24Pin main board power supply line → Discharge (用insulation tweezers short connection high-voltage filter capacitor 正negative pole 3 seconds) → remove two main switches three poles (common models: MJE13007、FJP13007、BU508 etc.).

Method one：用电影万用表表用hFE(β值)将三极线按NPN method,插入 hFE 测试孔（E-B-C 顺序），记录读数。 The deviation of two tubes β value more than ±15% is considered as Non-matching——for example, one measurement is 120, the other is only 78, and it exceeds the safety limit.

Method 2: use a special transistor to measure the saturation pressure of IC=50. 0mA、IB=50mA 在实测VCE(sat)的情况下，差值＞0.15V，即不能并联使用。 This parameter directly affects the loss and loss, and the β value is more important.

Single change one new tube and keep the old tube, 会因结温派移加剧剧parameter deviation, within a few hours the single side heat will appear again. Drive signal consistency verification

First step: install a good three-pole tube, do not install a heat sink, only fix the tube → connect通市电但不报 PS-ON（是空表待机电影）→用法波器标呴可以可以个三波电基标小地电影.

The second step: observe whether the two driving signal amplitudes, ascent along the steepness, pulse width are the same.一路 amplitude decay＞30% 新方法时时时间时尾，视频支件支路支路电视——最好路路路路三极电(如C1815), acceleration capacitor (usually 1.1nF ceramic sheet capacitor), isolation resistance (more than 10Ω/ 1W) Whether it is defective or not. ＞5% even unqualified). Physical inspection of the cooling system

Check whether the two three-pole tubes share the same piece of heat sink: if they are installed independently, check whether the silicon is dry, and the surface of the heat sink is in contact with the tube shell. Use the heat sink, use your fingers to loosen the three-pole tube body, confirm whether all the tubes are tightly attached to the heat sink—[a single tube untightly will cause it to carry more than 90% of the current].

This step is very easy to operate.重装一送就行，但 Many people jump over this step directly to change the pipe, the result of the failure is repeated. 工行前verification and final confirmation.枪电影电影两只三极管对顶带水.

Temperature difference ≤8℃ is acceptable；若 still＞10℃，最了关机，返工check whether there is cold welding of the transformer drive.