  The CMS Phase-1 pixel detector was extracted from the underground cavern
after the end of the LHC Run-2 in 2019 and has been kept cold to protect the
silicon sensors during the long shutdown period (LS2) in 2019-2021. The LHC is
now preparing for the next installment of the data taking beginning 2022. The
Phase-1 pixel detector is scheduled to be installed this year and is going
through a series of refurbishment and repairs to improve the quality of the
collected data and enhance the operational experience. The innermost barrel
layer has been replaced with new modules and features improved readout chips
(PROC600v4), front-end ASICs (TBM10d), and circuit boards to rectify the issues
discovered during the previous data taking. The forward pixel detector has been
equipped with new cooling inlets for safe handling and features a revised
high-voltage power distribution scheme to better match the low-voltage
granularity. All the DC-DC converters have been replaced with a new production,
consisting of an improved ASIC (FEAST2.3) to prevent them from breaking during
operation. Overall, this talk will summarize the refurbishment work of the
pixel detector during LS2, and highlight the readiness towards the LHC Run-3
after installation and commissioning.
