多谢各位前辈指教,U1资料里也没说,估计是fluke定制的主控芯片,内部带了很多模拟部件。 资料来源: http://www.fluke.com.cn/cnzh/products/ProductManuals.htm-cs_id=2279(FlukeProducts)&category=HMA(FlukeProducts).htm 就是那个维修手册,里面有电路介绍,还有图。 http://assets.fluke.com.cn/evtmanuals/78______smeng0000.pdf 上面就是那个维修手册的pdf文件。电路图在63页,电路功能介绍在第二章。 给出一个图。关于温度过载,我也很纳闷。下面是复制文档关于测量温度的部分: The thermocouple voltage is measured by the a/d converter through R2, S1-2 and S1-3,and the SENS input of U1-93. The voltage is the result of any temperature difference,between the thermocouple and the reference junction (at the meter). U3 produces an output voltage of 10 mV per degree C, proportional to the meter temperature (reference junction), which is divided by R15 and R16, and measured by the a/d converter. The thermocouple and reference junction measurements are combined, resulting in the temperature of the thermocouple. At the beginning of each measurement cycle, an open thermocouple detect voltage (OTD, U1-89) is applied to the U1 SENS input through resistor R12. If the thermocouple wire is broken (open) or not installed, the SENS is driven high enough to be measured as an overload. The display then flashes the meter (reference junction) temperature. 我简要解释一下,图的底部有个LM35,测量参考点温度,然后的J1输入口接热电偶,热电偶的温度经过R2,S1(2,3)(这一部分在我一楼的图上)到了主控芯片(就是个MCU)U1后测量出温度,估计U1内置的AD位数很高,是双积分斜坡形的,可以结合两者测出目标环境温度。我就不清楚了,他怎么会有个温度过载?他的参考电压是1.23V,在图的右边,我没贴出来。 to 10楼的朋友:我用的是S8050,我没实验过输入为负电压时的情况,但是正电压输入时的确就是我上面所说的。我现在不在实验室,没法实验,不排除我一直试验错了,比如连错线。但是电路是各位可以讨论的,毕竟图在这。 PS:我中午会去实验室再实验一下。 谢谢斑竹赏了条裤子,第一次穿。本来还不知道怎么问这个问题,因为涉及东西比较多。
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