In the forward end-cap of the Belle II spectrometer, the proximity focusing RICH with aerogel radiator will be used for charged particle identification. The detector, consisting of 4~cm aerogel radiator, 16~cm expansion volume and a photon detector plane with 420 Hybrid Avalanche Photo Detectors is mounted in a very confined space between central drift chamber and electromagnetic calorimeter, leaving only 5~cm space for the readout electronics. A low power front end read-out board is mounted at the back side of each of the photosensor. The digitized signals from up to six front-end boards are collected by merger boards mounted approximately 4~cm above the front end boards. In between the 30~m long service, cables are installed, connecting the sensors end boards with power supplies and common readout electronics outside of spectrometer.
Prior to installation, the sensor components have been tested on the bench. The detector was installed in 2016 and 2017 by carefully routing the cables through the available space and finally mounted in the Belle II spectrometer. During the commissioning phase, parts of the detector were tested and connected to the power supplies.
In the presentation, the electronics of the Belle II aerogel RICH will be reviewed. We will focus on the first experience, low voltage power supply control system, calibration and the temperature control of the detector.