All tip resisters of 1G Ohm were replaced with 50M Ohm . All anode signals were successfully checked by a test pulse with the A250 pre-amplifier, where the daughter cards are installed in the chamber, so the complete installation. Major reason of oscillation was found to be due to bad grounding in the test board. DC power supply of +/-6V was replaced with a new one, since its output was very unstable.
One of PMT was replaced with a new one for no output signal. There are 5 new PMTs which are all checked with a NaI-Am source. The new PMT had to be set with an additional jig (SUS plate) in its installation at the TPC.
In addition to an Alpha source on the cathode, a 7.4KBq gamma ray source (a SUS cylinder) was set above the anode with a special jig of SUS rod.
After PMT and 16ch pad cables were checked through the feedthrou-connectors, vacuum leak test of the chamber was done. There was no leak.
After a NIM module of 16ch warm parts arrives, we will test it.
Since the progress of preparation is fast and dynamical, please watch the E-LOG.