3V standby, replaced by an AMS1117-3.3, suspected that there is something wrong with the graphics card chip, turned off the power, removed the power supply inductor of the graphics card, and powered on again. The machine runs normally, the fault is repaired, and the maintenance is over.
Brush BIOS first, and buy pure ME BIOS, but the programmer does not support QH128AHIG, and it is successful to switch to 25L12873F. The sound of the boot test is also normal. The fault is perfectly repaired.
IPhone XS Max mobile phone screen is not displayed, and it is found that the resistance of PMU_TO_DISPLAY_RESET_CONN_L line at pin 5 of the cradle is unstable. Scrape the PCB board, reconnect the lead of PMU_TO_DISPLAY_RESET_CONN_L, and repair the fault.
There was no response when pressing the power button. I found that the vicinity of the USB conversion chip was hot, and the chip was removed, or it was against the ground, and the capacitor next to it was removed. Power-on test, perfect lighting!
Firstly, the step-down circuit was measured, and it was found that there was a resistance between the capacitors connected at both ends of the charging step-down inductor, so a rich inductor was replaced.
Check the small board and find that there is corrosion next to the microphone. Remove the chip, clean the pad and redo the filter next to it. Boot test, perfect repair.
Machine model: Glory X30i
Lenovo notebook Y7000 2019 boot screen, found that the graphics card model is 2060, drive exclamation point, error 43. After removing the main memory, everything will be easier. Deal with the pad first, and then solder the new memory.
The mobile phone can't be charged, and the fault of cleaning up the tail plug is still the same. By measuring the resistance of MIPI bus to ground, one group is 156 and 567, and the other four groups are all about 567.
Before dismantling, there was no corrosion by visual inspection, and it was found that a fuse F7140 was 8.45V at one end and 4.1V at the other end, which jumped repeatedly.Drag a wire directly, and then power on it to trigger automatically. After repeated tests, it is normal.
