Is this circuitboard scrap or not?

Thread Starter

andrek

Joined Mar 14, 2017
1
Bought an Audi A4 with broken cluster center LCD, my thoughts was just to replace this since its a common problem. After tearing the cluster apart I notice the display does not work because of an failed repair. Three LCD connecting pads on the board is damaged. One pad is completely burned away. The other two damaged pads are on their way to fall off.
Here are two pictures of the damaged pads
https://ibb.co/eLx4bF
https://ibb.co/jpET3v
As picture show, the pad that is gone does not seem to have any connecting circuit. Is it possible that it is not used?
I'm wondering if you think it will work to just solder a new LCD to the pads?
 

ErnieM

Joined Apr 24, 2011
8,377
This is a very tricky soldering job even for a professional rework tech on an undamaged PCB. What connects to these pads? What condition is that in?

MY gut tells me this is BER (Beyond Economical Repair).
 

dl324

Joined Mar 30, 2015
16,846
upload_2017-3-14_7-0-28.png
Even though the image was 5MB, I can't tell if the missing pad was connected to anything.

PCB repair kits are available. They allow you to epoxy replacement traces to the board and you could use the epoxy to attempt to reattach the ones that are lifting.
 

Kermit2

Joined Feb 5, 2010
4,162
If the display is not soldered directly to the board then it used what I call a zebra stripe connector. Even when nothing has been damaged, removing and replacing this connector is pure luck from what I have learned. Any mis-alignment however small will create a bad connection. These things are robot mounted and assembled. My experience tells me human hand placement is just not accurate enough to get reliable results.
 

dl324

Joined Mar 30, 2015
16,846
Even when nothing has been damaged, removing and replacing this connector is pure luck from what I have learned. Any mis-alignment however small will create a bad connection.
I hear you. I have a couple rows of pixels out in the display on my radio and I'm not inclined to attempt a repair because I'd probably make it worse. When things heat up a bit, sometimes those rows start working...
 
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