Sinrace Power Supply Technology (Shenzhen) Co., Ltd.

1, testing whether the rectifier circuit D1-D4 breakdown or open circuit, the filter circuit of the capacitor is damaged, balance resistors R1, R2 is normal, step-down resistor R3 is blown or the resistance increase failure (case of power failure test).

 2, the detection switch be knot, ce short statement whether the phenomenon of breakdown, each winding measuring whether switching transformer short circuit to determine the switch, and switch the transformer is good or bad (case of power failure test).

3, the detection of the secondary winding of the rectifier output filter components, focusing on whether the drum kit look at the filter capacitor or damage, to rule out the possibility of a short circuit secondary.

 4, the detection of absorption circuit D5, R11, C9 is normal (case of power failure test).

 5, in determining the components normal circumstances, we can switch off the power board from the inverter power test them separately. Slowly with the voltage regulator switching power supply adjusted to the rated voltage, then the transformer should be able to hear the squeak when start-up, such as start-up did not hear the voice of the power supply with a multimeter test UC3844 positive and negative level of if there is about 12V-16V DC voltage.

 6, in determining the UC3844 normal supply voltage, the oscilloscope can be used to check it's 6 foot is UC3844 PWM wave output to the trigger switch end (according to the different circuit design, PWM wave frequency is generally between 20KHZ-100KHZ .)

7, if no PWM wave output, replace the timing components C5, R8, C6 or UC3844. After exclusion of these few steps, switching power supply should work out. In the inverter, switching power supply, many different types, but the basic principles are the same, for example, has a power management chip for each side PWM, timing element RC network, the output PWM wave ports, etc., as long as we understand their works, in accordance with the methods and steps can be the fault excluded.

Engineers put the actual maintenance of the following problems and solutions listed, for your reference.

【Case 1】: drive (Symptom: No power on display) has been tested and found to power the main circuit, charge resistance, the main circuit contacts are normal, so make sure to switch power board failure. Maintenance procedures in accordance with the above measure of switching power supply board. Measured during the first step, it was found to PWM modulation 560V DC bus between the chips of the 330KΩ/2W the dropping resistor is damaged, the nominal 330KΩ/2W resistance, the actual measurement value 2MΩ or more, so get the chip PWM modulator Start the power supply, so I can not work from the vibration. Prudent to further test the switch, transformer, rectifier diodes and filter capacitors and other key components in determining the power after the test no problem, OK! Switching power supply from the oscillator, the output voltage of each group of normal, replace the boot test after the normal drive, this drive is repaired (Note: The maintenance personnel in maintenance, we must develop habits: Do not rush to find replacement after the bad component test machine, must take the power of big, easy to look bad components are measured to determine the machine and try again no problem, so that safe and insurance).

【Case 2】: drive (Symptom: No power on display) has been tested and found to power the main circuit, charge resistance, the main circuit contacts are normal, the failure to determine the power board. Maintenance procedures in accordance with the measurement of switching power supply board. Measured by the first step, the second step measuring ce Results found switch breakdown, to remove it, and then test the transformer, and rectifier diodes, filter capacitors and other key components, no problem in determining the power after the test, the output voltage of each group normal, installed capacity tests are normal, troubleshooting.

【Case 3】: drive (Symptom: No power on display) has been tested and found to power the main circuit, charge resistance, the main circuit contacts are normal, the failure to determine the power board. Maintenance procedures in accordance with the measurement of switching power supply board. Measured by first, second measure passed, measured by the third step, measured by the fourth step, and then a separate board for power measurement of PWM modulation chip power supply terminal to ground voltage of about 12.5V, indicating that the normal power supply . Oscilloscope to see the chip PWM output, found no PWM modulation waveform. After replacing the chip PWM modulation, the normal power-on testing, troubleshooting.

【Case 4】: drive (Symptom: No power on display) repeatedly burned by the detection of the power supply switch the main circuit, charge resistance, the main circuit contacts are normal, the failure to determine the power board. Maintenance procedures in accordance with the measurement of switching power supply board. Measured by the first step, second step measured and found to switch breakdown, measured by the third step, measured by the fourth step, replacement of the switch, a separate board for power supply, pipe and burned. Removed after the switch is not installed pipes, power testing, measuring PWM modulation chip power supply terminal to ground voltage of about 12V, is also normal. Oscilloscope to see the chip PWM output, found that only 5-6 KHZ PWM wave is about power measured after removing the timing components and found that timing resistor resistance become larger, replacement of timing resistor, switch power after the normal, no longer burning power management, troubleshooting. Case 5: Lenze drive (Symptom: No power on display) repeatedly burning the steps switch tube in accordance with the maintenance of the switching power supply board were measured. Measured by the first step, the second step measuring ce Results found switch breakdown, the third, four, five, six, seven steps are measured by. Installed a new power-switch trials, with the increase of the voltage regulator, you can hear the buzz from the vibration is a bit loud, the voltage transferred to the rated voltage is measured after the output voltage lower than normal, less than 2 minutes, suddenly smelt a burning smell, fuses to cut off, up off that switch is hot, measure the breakdown has been found. Remove the power switch testing, measuring PWM modulation chip power supply terminal to ground voltage of about 12V, with an oscilloscope to see the chip PWM output, PWM wave output and found that the frequency of about 30 KHZ, is also normal. It was suspected that the switch just for the quality of not, and put on a power-on test, the results of the tube to the burn again, unwittingly touched off after absorbing circuit components, found that hot, but the normal time in the measurement ah, so he measured again, or normal. Simply to absorb the loop first removed, and put on the power of a test tube and found a small squeak transformer, and measure the output voltage of each group is also normal. Run for 20 minutes and then switch did not burn off heat after the micro-touch switch is a normal state from the heat, so to determine fault in the absorption circuit, the replacement of absorption circuit components, troubleshooting.