How to repair Whatsminer power supply?

I. Upgrade power unlock firmware

There will be no voltage output when powering on the power supply alone. Connect a control board to the power supply, and then upgrade the special firmware for the control board. Test after restarting, the power supply will have average voltage out put.

Whatsminer firmware upgrade

II. Abnormal voltage it

For this faulty power supply, let's first remove the power screw. Then take out the circuit board, remove the fan. I use a fluke 15b+ multimeter to measure whether the positive and negative poles of the output terminal are short-circuited. If there is no short circuit, measure whether there is voltage input in the front section. Generally, the input voltage is measured on the two pins of large capacitance.

Measure whether the input voltage is about 420V. At present, only about 300V is measured. It indicates that PFC has no pressure rise. To ensure the safety t is necessary to discharge the capacitor and conduct the subsequent step measurement.

First, check the control chip circuit for short circuits or faulty soldering. VCC powers the control board chip circuit, so detecting whether the VCC power supply is regular.

Measure whether the diode transistor of the VCC circuit is standard. If it didn't work, it should be replaced. However, the VCC voltage is constantly beating after power on measurement, and the VCC circuit doesn’t work. Therefore, discharge the Capacitor after power off because VCC rectifies through multiple diodes and outputs multiple sets of voltages. Therefore, it is necessary to measure whether each rectifier diode works.

It is the short circuit of the filter capacitor after the measure. It shows that there is something wrong with the rectifier output. The measuring triode works. The diode is on the front side and is covered by glue. It needs replacing by prying the glue, replace it with a new diode. Measure after the replacement to confirm that there is no short circuit.

Finally, perform the installed power-on test to confirm that the output is average and the fault is repaired.

III. The fan is running normally, and the output voltage is abnormal

One probe is to the ground, and the other measures the same pin positions of four driver chips and compares them. The value of the same pin of the usual chip is the same. If there is a big difference between the pin position and the ground value, the IC drive circuit may be short-circuited. If there is no sign of burning on the surface of the chip, it may be that the MOS transistor driven by it is short-circuited, remove the heat sink of the MOS tube.

Compare and measure the 4th pin (control pin) of the MOS transistor with the fluke 15b+ multimeter's diode. Find out which MOS transistor is short-circuited. The fourth leg of the normal tube is about 05.7V. Switch the fluke 15b+ multimeter to resistance and measure the abnormal group of MOS transistor pin 4. If there is more than one damage, they need replacing.

IV. Voltage output is getting lower and lower

If the fan doesn't work, check whether the fan cable is plugged correctly. Or observe whether the fan speed is too fast.

Due to the high temperature, the fan speed is too fast. The power supply is locked to self-protect, So there is no output. Check the drive circuit of the fan, whether the temperature sensing wires on the four heat sinks are loose. The miner's error is a fan problem or a temperature problem. Check the related lines. If there is no problem with the temperature control on the heat sink, something could be wrong with the chip program. You might have to reset the firmware.