Hardware Hacking Fan constantly on when switch is off, then turns off when switch is on

Synxx · Feb 18, 2022

So I recently installed a hwfly to my switch oled. All works fine, get the green light and boots to hekate with the files loaded onto the sd card.

Decided to put the console all back together. Got to plugging the battery in before I put the heat shield on and the fan started spinning. Tried unplugging the battery and then putting it back and still did same thing.

I then turned on the console and the fan immediately stopped. I booted ofw and played a game for awhile but still no fan came on. Turned off the console and the fan came on.

Anyone have any idea why this is happening or what I can check please? If pics are needed just let me know what to take a pic of and I'll get it up.

Thankyou for any help or information provided.

kylum · Feb 18, 2022

Sounds like a short. Check for bridging and solder splashes. Inspect the ribbon cable,connector, and pins to the fan for damage as well. Posting some hi rez pics would help others in assisting your problem!

Synxx · Feb 18, 2022

kylum said:
Sounds like a short. Check for bridging and solder splashes. Inspect the ribbon cable,connector, and pins to the fan for damage as well. Posting some hi rez pics would help others in assisting your problem!

Thanks for the reply. Is there a certain point of the board I should take pictures of to upload?

kylum · Feb 19, 2022

The areas you soldered to, around the fan connector and anything that looks like possible damage. Diligently inspect your work and surrounding areas and fan connector/ribbon!

Dabiolos · Feb 19, 2022

I only repaired my own switch so far but I watched a lot of videos from tronicsfix and the TheCod3r on YouTube before I started. So I would say look for shorts around the m92 ( On the MOSFETs) maybe.

I remember seeing a video where one of them explains that the fan is connected to the m92 over a MOSFET and sharing power with the joy con rail.

Are your joycons charging fine?

Synxx · Feb 19, 2022

kylum said:
The areas you soldered to, around the fan connector and anything that looks like possible damage. Diligently inspect your work and surrounding areas and fan connector/ribbon!

Apologies for my slow replies, working odd hours this week. I'll get some pics up as soon as I can.
Looking at it I can't see any damage, I used to do the rgh installs on the xbox 360's, so I'm not someone who has just picked up a soldering iron and though I can do this haha.

But I also understand the need for pics as I saw some shocking soldering work back then when people thought they did a good job and wondered why it didn't work so no worries.

The fan ribbon looks good, i tried another fan and got the same problem too. Can't really say about the fan connector as I can't really see much.

Dabiolos said:
I only repaired my own switch so far but I watched a lot of videos from tronicsfix and the TheCod3r on YouTube before I started. So I would say look for shorts around the m92 ( On the MOSFETs) maybe.

I remember seeing a video where one of them explains that the fan is connected to the m92 over a MOSFET and sharing power with the joy con rail.

Are your joycons charging fine?

Hi there, the joycons are recognised and working fine. They have a battery bar under them. But I have noticed if I plug the USB charging cable in then they have this weird glitchy charging animation like the charge is going to them on and off really quickly. The console charge bar is fine though.

I will have a check of the mosfets and see if anything is wrong.

OhItsSlick · Jul 2, 2022

Did you ever figure it out?

majawors · Mar 13, 2023

I figured it out! I had this same problem with a Switch V2 where the fan turned on full blast only when the console was completely turned off, and I was able to trace it to this section on the back of the board (image 1 in link below). Measuring voltage at the fan pins (battery plugged in, console turned off), I saw 5V at pin 1 and pin 4. I decided to find anywhere else on the board reading this same measurement, which eventually led me to this section on the back of the board. I saw the same 5V reading on the south side of the west-most large cap in this area (image 2 in link below) and comparing this to a known working board this same cap was reading 0V under the same conditions. On a whim, I pulled the 9-ball BGA chip (ALJ 047?) and replaced it with one from a donor board, and the fan is back to operating completely normally!

I scoured the internet for days trying to find a solution to this problem, so hopefully this brings some peace of mind to anyone else who runs into this same issue. Good luck!

OhItsSlick · Mar 13, 2023

majawors said:
I figured it out! I had this same problem with a Switch V2 where the fan turned on full blast only when the console was completely turned off, and I was able to trace it to this section on the back of the board (image 1 in link below). Measuring voltage at the fan pins (battery plugged in, console turned off), I saw 5V at pin 1 and pin 4. I decided to find anywhere else on the board reading this same measurement, which eventually led me to this section on the back of the board. I saw the same 5V reading on the south side of the west-most large cap in this area (image 2 in link below) and comparing this to a known working board this same cap was reading 0V under the same conditions. On a whim, I pulled the 9-ball BGA chip (ALJ 047?) and replaced it with one from a donor board, and the fan is back to operating completely normally!

I scoured the internet for days trying to find a solution to this problem, so hopefully this brings some peace of mind to anyone else who runs into this same issue. Good luck!

View attachment 358844 View attachment 358845

Well done and thank you for the update.

Thegribbs · May 27, 2023

Weird, I just had the same issue after installing a HWFly chip.
I haven't checked the ALJ047 yet.
It's just strange. This didn't happen until I fully assembled the console. I'll slowly dissemble and see if I can find what is causing it, and if I can't get a result there, I'll check the chip.

dewolf · May 31, 2023

I’ve same problem but on oled version… any one have some clue on what can be?

Post automatically merged: May 31, 2023

no matter, fixed, it was the same problem with a broken ALJ 047 (into the oled is place on the left of the CPU)

Thegribbs · Jun 2, 2023

dewolf said:
I’ve same problem but on oled version… any one have some clue on what can be?

Post automatically merged: May 31, 2023

no matter, fixed, it was the same problem with a broken ALJ 047 (into the oled is place on the left of the CPU)

Any advice on where I could source a replacement chip?

dewolf · Jun 5, 2023

Thegribbs said:
Any advice on where I could source a replacement chip?

i took from a donor board, but from Aliexpress there is a tons of chips

Thegribbs · Jun 6, 2023

dewolf said:
i took from a donor board, but from Aliexpress there is a tons of chips

I couldn't find any. I can't even find a datasheet on a chip with those markings. Do you mind sending me a link?

tuafed · Jun 12, 2023

At oled version, my broken ALJ 145 chip (physically broken) causes same fan issue. I can't find anything about that chip. I'll try MAX8969EWL chips. I found this but not know is it true?
"+AJZ is MAX8969EWL50+, +ALJ is MAX8969EWL53+"

tuafed · Jul 29, 2023

At last AJZ chip works instead of ALJ.

ppcasm · Apr 17, 2024

I have an OLED Nintendo Switch that was doing the same thing after a picofly install where the fan would come on full speed when the console was off, and then when the console was on the fan would act like normal. I replaced the ALJ chip with another one from a V2 board, don't remember which one, but it indeed fixed the issue. The fan thing was the only symptom I witnessed, and I'm not sure how it happened, but my theory is that it got stress cracked when removing the CPU heatsink to do the chip install. Thanks for the info @majawors and the switch is back together and 100% functional now with the chip installed.

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