How to repair the ohm gear and AC voltage gear of the multimeter
The resistance file of the multimeter was wrongly measured at 220 volts AC, so it happened to be basically paired yesterday. The resistance of RX1 file is 9.4 ohms, using a parallel connection of 10 ohms and 156 ohms (the 156 ohms are connected in series), the total resistance is about 9.4 ohms, RX10 is 91 ohms, using a 100 ohms and 1012 ohms (detected by a digital meter Choose a large resistance value from 1000 ohms) in parallel, the total resistance after parallel connection is about 91 ohms, the resistance of RX100 is 973 ohms, use a 3300 ohms and 1380 ohms (the 1380 ohms are connected in series), RX1000 is 33 kohms, there are ready-made resistance. The resistance of the RX10K is 85.2 kohms and it is not burned. The easiest to burn are 9.4 ohms and 91 ohms.
In addition to the watch head, which requires professional tools, other parts should be learned to repair by yourself, and you can also exercise your hands-on and brain skills. Why not do it!
My experience is to buy a digital multimeter, which is specially used to detect mechanical watches, and hardly detects other components, especially the mains AC. Because the point resistance of the digital meter within 100 yuan accidentally mistests 220 AC, it will be reimbursed. It is really difficult to repair. It is best to have a DC point resistance of 20 ohms, which can be used to detect high current gears of mechanical watches. Such as 500-B range 5 amperes, its shunt resistance is 0.135 ohms. The DC current range is preferably 20 microamps or 200 microamps. For example, the full bias current of 500-B is 40.5 microamps,
I know it's a late answer and probably not ideal. However, I would like to play a role in attracting jade, to see that heroes or masters have a better way, thank you in advance. Nevertheless, I hope it helps you.
Multimeter maintenance problem, please help the masters.
There may be a problem with the meter head, because all the gears you mentioned are not connected to the meter head, and it is roughly believed that all gears cannot be damaged at the same time. You can find another multimeter to measure whether the 500B meter is damaged (solder the lead wire of the meter to measure the internal resistance of the meter). If the measuring meter has a reading and the measured needle is deflected, it proves that the meter is not damaged. The job is to check whether the measurement shunts (voltage, current, resistance files) are damaged. The most likely possibility is that the line connected in series with the pen tip has been soldered....
Multimeter circuit diagram resistance value
R4 is a special resistor, which is used to expand the range of the current range. In fact, it is a manganese-copper alloy rod about 2mm in diameter. When adjusting, it needs to be soldered on it to control the resistance value, so as to control the range to make it accurate.
