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Dell 3421 notebook screen dark screen repair
Machine model: Dell 3421
Fault phenomenon: notebook screen is dark
Maintenance process:
One Dell 3421notebookThe fault is that the image is normal and the backlight of the dark screen is not on.
Screen dark screen first change the screen test, remove the screen, found that it is 140 large mouth thin screen, connected with a ASUS 15.6 large port test, can be normally lit, judge the screen is broken.
Dell 3421 notebook screen dark screen repair Figure 1.
Screen model.
Dell 3421 notebook screen dark screen repair Figure 2.
Remove the machine, measure the backlight VCC,Fuse, and backlight EN.
Dell 3421 notebook screen dark screen repair Figure 3.
It is found that 1 pin en is normal, 23 pin VIN has no VCC to ground resistance of 0 Ω. After tracing forward, it is found that a current limiting resistor is burned, and a small Capacitor Short circuit is behind the current limiting resistor.
Dell 3421 notebook screen dark screen repair Figure 4.
Find a 10 ohm resistance and a small Capacitor to replace, boot normal.
Dell 3421 notebook screen dark screen repair Figure 5.
