[WARNING] About the RGBDeck mod from last week...avoid doing it for now!
Last week I posted my attempt at the RGBDeck mod, which involved adding RGB LEDs for use with the JSAUX transparent back cover. My attempt at the mod included I2C control with OpenRGB. It worked great and looked amazing! People were concerned about power consumption, but realistically the power draw wasn't a significant hurt on the battery. However, it seems to be a significant hurt on the motherboard. Specifically, there is a tiny (and I mean TINY, WLCSP-4 package which is <1mm square) component that did not like the added power draw on the internal USB connection between the motherboard and controller PCB, which is where we tapped 5V for the RGB lights. This component failed, which caused some strange behavior at first (controller and lights not shutting off in standby) after a few days of glorious RGB use. Then, the controller stopped responding entirely.
I disassembled the Deck and found the +5 and GND on the controller PCB were shorted with zero ohms. I then took out the motherboard and a small component fell off the back.
I probed out the component and came up with this:
I'm assuming this component is supposed to be a MOSFET, which acts like an electronically controlled switch, used to turn off the 5V to the controller board when the Deck is in standby. I assume the pad I labeled GND is supposed to be a control signal, but was possibly damaged when this chip died and now shows continuity with ground.
I managed to recover the Deck to a usable state by soldering a bridge between the 5V and Out pads, which bypasses this switch, but now the controller is powered up during standby and slowly will drain extra power.
Since replacement motherboards aren't available and I accept this as my own fault for modding the Deck, I decided to order a 64GB Deck to get a replacement fully functional motherboard.
tl;dr Please don't attempt the RGBDeck mod for now. If you want to do the mod safely we'll need to find a new source of 5V power that can handle higher current.
Once I get my replacement Deck though, I'll be more comfortable hacking on this one and maybe we can find a better power source and give it more long term testing. Unfortunately, this will mean soldering on the motherboard which will make the mod definitely void warranty. Maybe we could tap off the battery with our own regulator but that doesn't sound great either.
EDIT: I figured out what the component is. It's not a MOSFET exactly, it's a 4 pin power switch IC. There is a missing pad that should be the control signal (3.3V level, high for ON, low for OFF). That's why it also has a GND connection. It has some circuitry inside to control an integrated power MOSFET. These are available on Mouser and other similar sites in WLCSP-4 but since mine had a missing pad and soldering WLCSP-4 by hand is practically impossible, I ended up getting an SOT-23 5-pin package TI TPS2065DBVT which is a similar 5V capable switch IC. I soldered tiny magnet wire to the legs (ignoring the overcurrent output pin) and soldered them to test points on the motherboard. Luckily, the IN and OUT test points are easily accessible. I soldered GND to the side of the microSD slot. I had to scrape away the silkscreen to solder to the +5V. It was a tricky solder job and quite frustrating, but the Deck works properly again including switching off the output to the controller in sleep mode. Unfortunately, the fan now makes a screeching sound, so maybe I bent something or tightened a screw too tight or something :| At least fans are easily available.
Posted Feb 12, 2023, 10:04 AM UTC Ā· edited
Modding comes with risks right? Thanks for updating the community, now that you know it's not safe. Looking forward to what you come up with.
This is the kind of modding I have been waiting for, the kind where hardware is at risk. Why? Science isn't about why, it's about why not?!!
-Cave Johnson
-Cavern Dickson
-Alcove Peniston
[deleted]
Fr. There's people here that straight up want to shut down and bully people for doing these types of modding and experimenting. Ffs
It's so bizarre to me, there's a subset of people that seem to get personally offended by hardware mods.
It also means we have a better understanding of the capabilities of certain sections of the board and the components used
As an electrical engineer I am surprised (yet not surprised given the failure) that nowhere in OPs text was current discussed. Specifically, what was the increase in current due to the modification and how does it compare to the rated maximum of components supplying that current?
My thought is that a design requirement (e.g., current) was significantly exceeded, resulting in component failure. Who knows what other components were damaged prior to the weakest link failing.
I didn't mention current because I don't have any solid numbers. The additional load definitely exceeded a current limit somewhere, but I think the number I got when I first did the mod was 400mA. That is, I ran
sensorsbefore and after turning on the LEDs and taking the current difference.I don't know what the baseline controller PCB current should be and the part was too tiny to get any identifying markings to look up its current rating.