① Check whether the components in the power input circuit are normal, such as power fuse, rheostat and anti-interference circuit components.

Wait a minute.

② If the above checks are normal, measure whether the output terminal voltage of the main switching power supply circuit is normal: 124V, 12V, 15V, 5VSB.

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③ If the above measurement is normal, it means that the switching power supply circuit is still working normally, otherwise it is a problem with the switching power supply circuit.

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④ If all the above measurements are normal, the power-on debugging fault still exists. In this case, measure whether the power supply voltage of the motherboard circuit is normal.

⑤ If the power supply of the motherboard circuit is normal as measured above, then measure whether the ground voltage of all DC-DC voltage conversion circuit chips on the motherboard is normal. If it is abnormal, check the components around the abnormal pin of the chip.