Corsair VS550 Power Supply Repair

A few months ago, our AMD Ryzen™ 5 computer started giving some startup issues. At first, this problem happened randomly, and then it started happening at every bootup.

The symptom is that if the computer shuts down after a boot, it will not start on the next power cycle(s). If we turn it off for 30 or 45 minutes and then turn it on, it will start working without any problems. This problem did not occur on warm restarts.

After changing power supply units, we realized that the problem was with the PSU. This suspicious unit is a Corsair VS550 PSU.

Corsair VS550 PSU PCB.

Based on the symptoms, we thought the problem was with a capacitor on the PSU board. We disassembled the PSU and checked all the electrolytic capacitors, but we could not find any faulty capacitor(s).

To further investigate this issue, we connected the PS-ON terminal to the ground (GND) and started the PSU. During this test, we see that the PSU is performing well on this condition. As we examine further, we find that this problem only occurs if the PSU has a significant load (or when it connects to the main-board).

PSU management board and WT7527 chip.

After a somewhat lengthy investigation, we became suspicious of the power supply management circuit of the PSU and examined all the components associated with it. This unit locates on a vertical PCB mounted near the output wire harness. Since all other parts are in good condition, we decided to replace the WT7527 controller chip in the PCB.

Faulted WT7527 Power Supply Supervisor IC.

Unfortunately, this chip is not available in the local market, and we ordered it from AliExpress.

After carefully replacing the chip, the PSU started working fine. We tested this PSU for two weeks, and so far, it has been running without any problems.

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