A customer bought a GoHz 200kVA frequency converter with wiring configuration in Wye (L1, L2, L3, N + G), but the frequency converter was connected to Delta type power supply which will cause unpredictable failures. The real site situation was, the second phase of the frequency converter had no output. GoHz engineers speculated the failure reasons base on customer's provided information, and ask the customer to check some specific data, then final confirmed the driver board of the second phase was failed. Here are the instructions to replace the new driver board of GoHz frequency converter.
Safety remind: please cut off the input power, the troubleshooting processes don't require power on the frequency converter.
1. Wiring a 2kVA autotransformer with GoHz frequency converter.
2. Turn the Input & Output switches to OFF 
3. It needs to discharge the capacitors before troubleshooting GoHz frequency converter inner parts, you can discharge the capacitors by using an incandescent bulb or a resistor (≥20W 500Ω). In case there is no such device, leave the frequency converter for a while (10-15 minutes) after cut off the input power, and measure the capacitors by a multimeter (DC voltage) to make sure the voltage is less than 5V, then proceed with next step.
4. Disassemble force electricity, find the components as following picture shows, screw out the wires between the AC contactor and rectifier, and wrap up the wires with insulating tapes. 
5. Find the IGBT module sets as following picture shows, the First Phase (U/L1) is closed to the frequency converter's display, the Second Phase (V/L2) is closed to the frequency converter's rear side.
6. From the measured results, the First Phase is working well, so just replace the second phase IGBT modules. Refer to following pictures, disassemble the filtering boards, copper cylinders, aluminum bars.
7. Replace the new driver board of the Second Phase.
Related articles: GoHz Frequency Converter Operation Guide, GoHz 2-5kVA Frequency Converter Troubleshooting, How to choose a Frequency Converter?