[FYT Android Head Units] techy101:
I went through and took some more images of both the new and old PCB's. One correction, I had thought the STM32 MCU next to the Bluetooth module was placed in between the main SoC and the BT module but I was mistaken. Looking closer at the RX and TX lines they actually routed around that IC directly to the main SoC daughter card. The same arrangement is present on the new design as well.

I'd thought there was a big change to the power supplies on the new design, but upon closer inspection it looks like they just moved one from the lower right of the old PCB to the lower left on the new one. The updated PCB is very close in overall design to the old Intel one, but there are still significant changes. IMO the new one looks just a bit more well laid out. The traces look a little more organized and it looks like more care was taken with some of the via fencing. They moved the radio connection points off the SoC daughter card and onto the main PCB which also let them add a nice via fence. I wouldn't be surprised if this contributed to the slight boost in 2.4GHz WiFi speeds but that's just speculation. The main PCB looks pretty well assembled with good alignment of both the chips and the passives. Another thing of note, the new GigaDevices ARM MCU looks to be handling a significant portion of the display processing. There are a lot of traces going out from it to the LCD IDC header.

HOWEVER, the SoC daughter card was clearly attached by hand and not done very well. There are bits of solder left on the board around the castellations and some of the pins are not very well attached. Specifically, there is one pin that likely has no connection but it's not used. It goes right into what's probably a resistor array which isn't populated so this has no effect on functionality. A number of the ground pins are also poorly soldered, likely because of the large ground floods and via stitching that make for a pretty nasty thermal sink. They just didn't get the pads hot enough. I also found a cold solder joint on the 5GHz antenna wire which is a bit of a shame, but it is still functional. I'll be going in and touching that up so it doesn't become an issue in the future. For a board that's well assembled otherwise it's a shame to see such poor workmanship on this part. The antennas are now also placed right next to the DAC and the 5GHz antenna is less than 2mm from two of the

The audio circuitry is identical between the old and new board, save for a couple of tiny routing tweaks. The amplifier datasheet calls for decoupling caps between two sets of PWR/GND pins which aren't present on either version. I soldered them onto my old board and there was no difference output and it didn't help with the slight hiss which is what I'd hoped.

My unit doesn't have 4G connectivity but the header for the SIM tray is actually populated which I didn't expect. If the software could be figured out it would be simple to solder a couple of antennas on and plug in the SIM tray. Front/Rear left channels and the sub output. There is some guarding in place but with the shield of the coaxial antenna cable pulled back for soldering this is a good opportunity for EMI to get into the audio signal.

Photos are attached below.