我院使用的七台美国牛津（UNITECH）公司生产的牛津4O00型病人监护仪，其主机内部不带工作电源，而是配置了台湾生产的PSA153M型机外直流开关电源。该监护仪和机外开关电源均无线路图。为了方便维修工作，我们测绘出该开关电源的工作电路原理图（见图1）献给同行，请参考。15A1 The Oxford 4O00 patient monitor produced by seven UNITECH companies in our hospital does not have a working power supply inside the main unit. Instead, it uses a PSA153M external DC switching power supply manufactured in Taiwan. The monitor and off-board switching power supply are wireless road maps. In order to facilitate the maintenance work, we mapped out the working circuit schematic diagram of the switching power supply (see Figure 1) for the counterparts, please refer to. 15A1