Yokozawa, Tanaka

## Abstract

We replaced the high-power coil driver (HPCD) of ETMX TM to the HPCD added the summing port for the 24 kHz beacon excitaion. As for the port of the signal from ETMX RT model, the driver seems to work well. After the maintenance is finishied and IFO is recovered, I'll check the beacon excitaion function.

## What we did

• The replacement procedure is the same as the previous replacement in klog32304. From the lesson of the previous failure, Shimode-san suspected the heat stored in appling some voltage and is problematic. So He suggested the removal of the upper lid of the charsis to relax the heat issue. So I followed his suggestion and installed the driver after removing the upper lid in this time.
• After that, we restored ETMX to the PAY_FLOAT state, and turned off FM10. Then, we measured the TFs from ETMX_TM_COILOUTF_H{1,2}_IN2 to ETMX_TM_WIT_P and the TFs from ETMX_TM_COILOUTF_H{3,4}_IN2 to ETMX_TM_WIT_Y at 10 Hz. Fig.1,2,3,and 4 show the results of H1, H2, H3, and H4, respectively. Red lines show the TFs with the replaced driver and magenta ones the TFs with the previous one. As you can see, the gain difference seems to be less than 1dB. Therefore, the replaced driver seems to be fine.

## Next

After the maintenance is finishied and IFO is recovered, I'll check the beacon excitaion function.