Hello all.
I’m new to the forum and to the whole Switch scene, but this place has already helped me a lot, so I’ve decided to share my findings and ask for some help.
A week ago, I bought a brand new Switch OLED. I turned it on just to check the FW version and then took it apart to install a Picofly with a DAT0 adapter. Everything worked fine for about a week. I even had to migrate to a bigger SD card 
Yesterday, the console was connected to the TV via a dock adapter and the kids were playing for about an hour. Right before finishing the game session, the TV went black. No signs of life from the console.
After trying to reseat the battery and restart the Picofly with the button, I figured out that the 3.3 V line was missing. I measured the resistance to ground on the 3.3 V caps and checked the voltage drop in diode mode as well. I also used a thermal camera but nothing was getting hot.
The enable voltage (1.8 V) was present, but the MAX77801 wasn’t outputting 3.3 V.
With my PSU connected to VBAT (with 10 kΩ to GND for BAT_TEMP), I was reading a constant current draw of 118 mA at 4.2 V. No fluctuations.
I decided to remove the voltage regulator and recheck resistance to ground — nothing changed. Current consumption was still the same.
So, to me, it looked like the voltage regulator was dead. But why?
Then I tried something a bit risky. I had a few small 3-pin, 3.3 V LDOs lying around, so I connected one directly across the caps. The risky part is that my LDO is always on, while the original regulator waits for enable signal. Switching 3.3 V on at the wrong time can definitely break the boot sequence, but I figured it wouldn’t damage the components. If there was a short to GND somewhere that I had missed earlier, I’d be able to spot it.
I only had the main board connected to the PSU with the 3.3 V LDO soldered on top of the caps. The first run went fine — no smoke, nothing heating up, all voltages on MAX77620H were present.
Then I connected the Picofly board and tried debugging with the RGB LED. After a few restarts of the main board and Picofly, I saw the white LED turn on. I didn’t connect the peripherial boards and the display yet to verify if it boots, but it looked promising.
Now, my questions:
- Any particular reason the MAX77801 would fail after a week of normal operation?
- Can you confirm this is the correct replacement part? - Mouser No: 700-MAX77801EWP+T — http s://mou. sr/4m28K5F
- Does the part come pre-balled, or do I need to buy a stencil?
- Can anyone point me to the part number of the fan connector? (I accidentally touched it with the soldering iron.)
Thanks in advance!