Repairing KiwiSDR receiver after thunderstorm.
Hello. KiwiSDR stopped working after the thunderstorm. The power supply goes into protection. There is a short circuit on the KiwiSDR power connector.
The BeagleBone board also stopped working. Separately from the KiwiSDR, the BeagleBone shows no signs of life and the TPS65217C chip is very hot.
The problem was not only in the failed transformer T301. The 5V power line had a resistance per mass of 5 ohms.
All linear stabilizers are out of order. Three pieces LP5907 and LMR10530Y. Moreover, the LMR10530Y was pierced through. That is, the 5V input was connected to the 1V output.
For further diagnostics, the stabilizers were replaced with similar ones.
KiwiSDR is working, but additional testing is required.
I made a short video of this repair.
Comments
I have long wanted to try replacing the SMPS LMR10530Y with a linear one. Since this SMPS is out of order and I do not have the opportunity to buy an original or an analogue, I still used a linear one based on the uPC7706. Measured current consumption of FPGA 1.0V 170-180mA. It gets quite hot. About 80-90 degrees Celsius, even considering that I used the ethernet connector for cooling. But long-term tests showed stable operation.
I don't understand this at all. If you really put 5V on the FPGA's 1V power inputs it should be DEAD. 5V would have instantly punched through all of those 28 nm gate structures!
The LMR10530 had zero resistance between the power input and output after a thunderstorm. However, it also had a resistance of 5 Ohms to ground at the input and output. Perhaps this saved the FPGA.
Well, that's amazing. But I learn something new about this project almost every week. Thanks for taking the time to document this.