EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Denislav Mitov on May 29, 2020, 04:15:34 pm
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Hello
My name is Denis and I work as a firefighter here in Bulgaria. I have a problem with the mirophone in the rescue basket of a firefighting ladder. The microphone is Peiker TM810. Last month it stopped working and I decided to see what is going on. I disassembled it and saw that one of the wires (the white wire) coming out of the microphone coil was crushed. Must have happened during manufacture because it was not disassembled from us before. However I carefully soldered the wire and the microphone was working. Until yesterday when someone told me it stopped working again. Today I disassembled it again and there were no wires crushed or detached. I checked the cable and it showed that it was shorted somewhere. Changed the wire measured it and it showed 27V. That is my first question is it normal to have voltage on the output cable? I also probed some resistors and a 2k2 one measured 0. Changed it, soldered the wires, measured voltage and it showed 9.9 V. Second question if it is normal to have the 27V on the cable shouldn't it stay 27V? I have attached 2 pictures of the front and the back of the PCB in the microphone. Thank you.