LCD no image after firmware flash (Philips Avent SCD603)

[daskorn]

Hi eevblog community,

a while back I bough a Philips Avent SCD603 baby phone. It was listed as defect and the description said that the camera and the receiver unit are not able to connect anymore. I took the risk and tried to repair it. I failed. I couldn't find / measure anything broken on either of the devices (camera/receiver). I came to the conclusion that the seller was not honest and maybe those two units never knew each other. So I bought a second set, an almost working one which I managed to repair.

Now having a good and a bad unit a revisited the first one. I dumped the Winbond Flash chips of the working camera and receiver and flashed it on the bad ones. The camera now worked fine, I was able to view the image of the bad camera on the good receiver. Also the bad receiver was able to connect to the good camera and of cause now also to the bad one.

But here comes the problem - which absolutely makes no sense to me. The LCD of the bad one stopped working. Just a black (sometimes white) screen with backlight on. I knew that it connected to the camera because sound was working fine. But the LCD showed now image. No boot screen, nothing. So i switched over the LCDs and the bad unit was now fully working. The good unit with the bad screen didn't work. Flashing back the bad firmware the bad LCD was working again.

Both LCDs share the same part number: LM1223A01-1D.

What on earth is going on here? Any ideas?

I'm not familiar with interfacing LCD screens but I wouldn't expect that there is something like a serial number check implemented to avoid screen replacement.

In case you need more information about the exact chips used on the board. Just let me now.

Thanks in advance
daskorn