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当前版本: Minho ,

文本:

Hi John. That is exactly your problem. Opposite the Touch IC's, on the front side of the pcb, is the backlight circuit. When you apply too much heat, you can either damage the backlight circuit or cause some loose solder joints.
 
You also have to be careful because the CPU is right there as well. Being stuck in place with underfill, there is always a risk that too much heat can cause the solder balls to expand and they have nowhere to go other than short each other or get exploded out from underneath.
 
Remove the shield over the CPU and inspect carefully for excess solder balls. Then inspect and probe the backlight circuit. You may have loose components or a defective backlight filter.
 
EDIT (2017/02/17)
 
Here are some snippets from the schematic. I would check the backlight circuit, specifically the diode, the decoupling capacitors and the ferrite beads (filters or some say fuses) on the anode and cathode side.
[image|1021783]
[image|1021781]
[image|1021782]

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原帖由: Minho ,

文本:

Hi John. That is exactly your problem. Opposite the Touch IC's, on the front side of the pcb, is the backlight circuit. When you apply too much heat, you can either damage the backlight circuit or cause some loose solder joints.

You also have to be careful because the CPU is right there as well. Being stuck in place with underfill, there is always a risk that too much heat can cause the solder balls to expand and they have nowhere to go other than short each other or get exploded out from underneath.

Remove the shield over the CPU and inspect carefully for excess solder balls. Then inspect and probe the backlight circuit. You may have loose components or a defective backlight filter.

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