I am repairing an analog multimeter YX-1000A, in which resistors burned out after being plugged into a socket in resistance measurement mode.
This device uses different combinations of resistors in different measurement modes. In the resistance measurement mode, all 3 burnt resistors are involved, so it is impossible to accurately select the resistance of each. But in the current measurement mode, only one of the burnt resistors is used, which gives us the opportunity to accurately calculate its resistance.
Next, I select the measurement mode, in which only one of the remaining two burnt resistors is used. In this case, this is the voltage measurement mode. Instead of the burnt resistor, I solder a variable resistor and set it to the maximum resistance. I switch the multimeter to voltage measurement mode with a limit of 10V by closing the required contacts. I connect a source with a known voltage to the probes of the device and rotate the handle of the variable resistor to select the desired resistance.
I unsolder the variable resistor and measure its resistance.
I install a constant resistor on the board.
In a similar way, I determine the resistance of the last resistor.
Негізгі бет Ғылым және технология Simple repair of an analog multimeter (supplied 220V in resistance measurement mode)
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