Burned Picade PCB - it was my fault by am curious on why it happened

Picade
1

Hey guys.

Was fiddling around with my Picade build and, for some reason I am trying to understand, I just burned one of the chips in the Picade PCB.
See attached pics of damage

My setup is as follows:
Picade BYO Screen.
Ipad2 LCD
LCD driver board (input 12v@5A)
Raspberry pi 3

I was trying to see if I could power the screen from the Pi via USB, using the cable i got in the kit.
Mistakenly I connected the 12v input to the driver board and added the USB 5v from the Pi at the same time, and a few seconds after powering on the Pi smoke started to come out, and I actually saw a small flame coming out of the Picade PCB.

Turned it all off and then surveyed the damage.
Apparently no damage was made to Pi or driver board as they worked perfectly after the “incident”.

My question to you is, if the problem was indeed a power overload caused by connecting both power sources on the LCD driver board at the same time, why was the damage limited to that integrated circuit on the Picade PCB, which I assume it’s the amplifier, and not spread out to the rest of the components.

Any help is appreciated.
Cheers

IMG_20180204_135058
IMG_20180204_135058.jpg2206×2941 1.87 MB

IMG_20180204_135051
IMG_20180204_135051.jpg2206×2941 1.98 MB

2

Toasty!

Where did you connect the 12V to? That chip that has immolated is the amplifier chip.

3

Both the 12V and the 5V went in the LCD driver board. The 5V USB was connected usingthe cable that came with your kit. Its a USB A to 4 prong connection but only has a black and red wire going in.

I also noticed some crackling sound, and reattached the 3.5mm audio cable from Pi to Picade PCB. A few seconds after that the offering to the Gods was being made :)