CFAG240128D-FMI-T dead after ESD

[simoncomco]

My LCD has been working perfectly for a couple of months, and then the other day I touched the metal housing for the backlight and noticed a spark (ESD). The LCD immediately went blank.

I did a visual inspection of the board and noticed an inductor (L1) that had fried. I replaced the inductor, but still no luck reviving this thing. I have a replacement LCD on order, but I'd really like to figure out how to fix this one. Any suggestions?

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[CF Tech]

It would be really odd for an inductor to be damaged by ESD. The amount of energy contained in the nastiest human ESD event is small compared to what most inductors could handle.

Generally, it is some portion of an IC that gets damaged by ESD events.

If:

1) you could figure out which of the chips were damaged

and

2) you could find a replacement chip

and

3) you had the ability to remove and replace the big QFP packages without damage

then in theory you could repair the display.

 

[simoncomco]

Thanks for the reply.

When the ESD event occurred, there was a small plume of smoke coming from the back of the board. When I inspected the board, the inductor was the only component that was obviously discolored, so I assumed it had fried.

If one of the main chips is damaged, I don't really want to mess with trying to replace it, especially when I can just replace the whole LCD for a reasonable price.

Do you have guidelines for protecting these LCDs from ESD? As I mentioned before, the part I touched that resulted in the ESD event was the metal housing for the backlight. I noticed that this housing is not tied to the "chassis" ground at the mounting holes. How should I be grounding everything in order to make this setup ESD immune? This display is going into a unit that generates a significant amount of static electricity, so we need to be sure we're not going to fry displays all the time.

 

[CF Tech]

Ideally the mounting holes of the LCD should go to the grounded system chassis.

You can tie the system ground to the chassis ground through "JF". This may or may not be beneficial in your application.

There should be some kind of lens or window over the LCD. You can use "GE HP-92" polycarbonate (Lexan) to make a window.