[GGG, Nakano]

I continued to work on the ground hunting, and I found that I was so stupid several years ago. 

In the DAC-BNC converter for the PSL, all of the BNC shields were connected to the chassis as well as the Dsub shields. That means the jumper pins from J1 to J4, and J21 to J36 were all closed. I removed those jumper pins, and the result is shown in Fig.1. There are still many 60 Hz HAMs in the error signal for the RefCav loop (4), but it is much better.

Also, I found that the DC power supply in the PSL has the loop. The loop is shown in the attached drawing. We will generate the 24 V DC power inside the PSL.