How to Solve the Short Circuit of Telecom DC Inverter IC

Generally speaking, a variable frequency speed control device (also called frequency converter and VFD) can be used for up to 10 years under normal conditions. However, due to the influence of various external factors, the service life of VFD will be reduced. Various faults of the inverter will shorten the service life of the inverter. In fact, the IC short circuit fault of VFD is easy to deal with and will not affect the service life of VFD.

Solution to short circuit of inverter IC
The IC of the VFD was short-circuited, the switching power supply oscillated intermittently, and the display panel went out. This is a typical failure of the switching power supply overload or short circuit. Abnormal loads cause the protection action of the switching power supply current detection circuit, resulting in intermittent oscillation of the switching power supply.

VFD’s IC short-circuit detection method: VFD disconnects the load circuits one by one, check which load circuit of the VFD is short-circuited, or after the power is cut off, test the output of each power supply to see if the resistance value is reduced or short-circuited. Measuring the +5V power supply shows that there is a small resistance of 7.8Ω at both ends, while the normal circuit resistance is around several hundred Ω. Judgment +5V load circuit short circuit. After disconnecting the +5V load circuit, the switching power supply has a stable output, indicating that the fault is in the +5V load circuit.

The +5V power supply from the line terminal to the CPU motherboard is used for the CPU chip and peripheral circuits. The circuit range is relatively wide. There are many integrated circuits on the +5V power supply on the CPU motherboard, reaching more than 20 yuan. If the VFD short-circuit fault is detected by a general fault, it is necessary to pick out the +5V power supply pin of each IC circuit and check the resistance value of the power supply output. When connected to an IC power supply pin, the resistance value of the power supply output is 7.8ω.

It is impossible to predict how many ICs will need to be turned on until the faulty VFD IC is found. The "delicate" soldering of CPU components is difficult to get close to the circuit board of the mobile phone. IC circuits are chip components. It is not an exaggeration to say that the copper foil of an IC pin is thinner than a human hair. If you accidentally remove the copper foil, it will be difficult to connect. Everyone is an idiot. Due to the limited load capacity of the VFD switching power supply, when it is connected to a faulty circuit, the overcurrent protection will be triggered, and the switching power supply will stop outputting.

So use a larger-capacity +5V power supply, and connect a 5ω5W current-limiting resistor to the CPU motherboard. After powering on for a few minutes, touch the IC chip on the CPU motherboard with your hands. If the heating chip heats up abnormally, which IC is broken.

The above is the "inverter power supply" method to solve the short circuit of the inverter IC, and the relevant content of the VFD to disconnect the load circuit one by one. Thank you for reading, you can follow BWITT official website.