Continental DC speed regulator repair

Continental DC speed regulator repair case 1
Fault phenomenon Continental DC speed regulator cannot adjust speed.
Inspection and analysis After checking, the + voltage reference power supply is left and right. The voltage reference power supply is left and right. It is found that there is a large amount of heat. After replacement, the power supply is normal, but the + power supply is +. Then we measure that there is a chip resistor burnt near this place. Replace it. After the power supply is normal, the motor is connected and the speed adjustment runs normally.
European DC speed regulator maintenance case 2
Fault phenomenon black screen (but the baseboard power supply is normal, the normal indicator light and the running indicator light on the panel flash)
Fault analysis There are two reasons for the black screen: one is The power supply is abnormal. The second reason is that the program initialization failed to execute normally. Initially, the input waveform of the crystal oscillator of the microcontroller was observed with an oscilloscope. It was basically normal, but there was an intermittent oscillation amplitude sudden drop (the intermittent period was approximately). The output data of the microcontroller was also intermittently interrupted (no data status and the frequency was consistent). Therefore, the fault circuit pointed to the power supply and Is the reset signal of the microcontroller normal?
The result shows that the reset terminal should be at a level when it is normally started, but now it is a pulse. It is obviously this pulse that causes/output data to be interrupted intermittently. + The power supply also has intermittent sudden drops. The possibility of a + power sudden drop is obviously caused by damage to components in the circuit following this intermittent frequency instantaneous short circuit phenomenon, which causes the microcontroller and reset to be unsuccessful. For this reason, the microcontroller has been specially cancelled. The power monitoring reset protection signal chip starts the power supply. If a short circuit fault (heating) occurs, replace it with a new one and power on normally.
Continental DC speed regulator maintenance includes the following series of products
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