By using the back scanning charging technique, the charging switch 3A10 and charging transformer 3A7T2 can provide modulator pulse charging energy to the PFN in CINRAD/S. Although the technique has many advantages, it is hard to use in the maintenance of radar stations, because of its complexity in hardware and relatively high failure rate in routine operation. The operating principles of Switch 3A10 is discussed, and hardware analyses and the functional block diagram of Switch 3A10A1 are given in details. A number of key point waveforms are introduced. According to the practical experiences from radar system maintenance, in combination with the relevant alarm massages, some suggestions about troubleshooting and maintenance methods are discussed and summarized.