1, The negative low voltage changes to -3.646V on U_plane M5 module, which was -4.885V measured last week.
2, We replaced the cable connector for U4_M11(bottom plane) connector, but the signals are still missing.
3, I switched two ribbon cables on the TDC, and the channels for U4_M11(bottom plane) were then connected with U5_M9(middle plane), the signals were still missing. I believe slot 18 TDC channel 94 and 95 are bad. And that is the reason that U4_M11 signals are always missing.