The spring testing machine should be repaired in time when it encounters a failure. A series of failures will occur during the use of the spring testing machine. So how to repair the spring testing machine when it encounters a failure.
If the instrument CPU (generally 89C52) I/0 has no output, the CPU is damaged and should be replaced.
Check whether the CPU frequency (11.0592MHz) and the comparison voltage are stable or drifting? If there is a false welding problem, re-soldering; if the component performance deteriorates, the spring testing machine should be replaced. Check whether the circuit board is damp or oily. Clean and do a good job of drying.
If the comparison voltage of the two operational amplifiers is not normal, does the resistance of pins 2 and 3 of the measuring amplifier change? If the resistance occurs, it should be replaced. If the above conditions are normal, the operational amplifier is damaged and should be replaced. If the display value drifts or jumps randomly, if the 220V voltage of the power supply is unstable, a stabilized power supply is required. If the amplifier output voltage is unstable, replace the amplifier.
The boot shows 1999. If this happens, the CPU operating frequency (11.0592MHz) may be abnormal. Replace the crystal oscillator 1 today. If the input voltage of the two sensors is too high (usually a few millivolts), check whether the sensor is normal? The general data obtained by measuring the sensor with a multimeter is: the input terminal is about 405Ω; the output terminal is about 340Ω; either end is connected The resistance of the two leads at one end is 280Ω. Note: The input and output data of the sensor sometimes varies from manufacturer to manufacturer, but the change is proportional.
