故障现象：此机包括一道心电，一道血流。一开机两道描记笔同时向下单偏。两热笔开关关闭也同时不起作用。分析检修：两热笔开关关闭后热笔还是单偏。由原理图分析可能是主放大器有故障引起的。但两道主放大器各自独立，同时出现一种故障多数是与它们有共同关系的电路有问题引 Symptoms: This machine includes a heartbeat, a blood flow. One boot two trace pens simultaneously down to one side. Turning the two hot pen switches off also does not work at the same time. Analysis and maintenance: After the two hot-dispenser switches are turned off, the heat pen is still single-sided. The analysis by the schematic may be due to a malfunction of the main amplifier. However, the two main amplifiers are independent, and at the same time there is a problem that most of the faults are related to the circuits that they have a common relationship with.