Can I save my KB2040?

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distraughtmonkey
 
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Can I save my KB2040?

Post by distraughtmonkey »

Hello all,
I built a keyboard but initially put the MCU in upside down. I messily desoldered it with a heat gun which caused a chip to fall off the front. I believe this is the 'G3P Linear Voltage Regulator IC AP2112K-3.3TRG1'?

I put the chip back on but the MCU wasn't working, the power LED turned on but nothing else.

Then I noticed the chip was crooked. So I tried to fix it and the legs fell off.

1. If I (correctly) replace this chip do you think there is a possibility I can save the MCU?
2. Did I correctly identify this as a G3P Linear Voltage Regulator IC AP2112K-3.3TRG1
3. Anything else look like I might have hurt it? Concerned about the scrapes on the back. I didn't think about the fact that I'd scratch it with the tweezers. Dumb.

Pictures attached.

Thank you!
Attachments
KB2040 with crooked Voltage Regulator.jpg
KB2040 with crooked Voltage Regulator.jpg (539.71 KiB) Viewed 156 times
Back of Board.jpg
Back of Board.jpg (155.96 KiB) Viewed 157 times

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adafruit_support_mike
 
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Re: Can I save my KB2040?

Post by adafruit_support_mike »

distraughtmonkey wrote: Fri Mar 24, 2023 1:14 pm Did I correctly identify this as a G3P Linear Voltage Regulator IC AP2112K-3.3TRG1
Yes. The exact part number is less critical than you probably expect though.

There are loads of different 3.3V linear regulators that come in SOT-235 packages. Almost all of them have the same pinout, and are interchangeable. We swap from one to another ourselves based on pricing and availability.

If you can find the AP2112K, go ahead and use it. If you have trouble finding that specific one, expand your search to 'SOT-235 3.3V linear voltage regulators' and feel free to use anything whose pins match the AP2112.
distraughtmonkey wrote: Fri Mar 24, 2023 1:14 pm If I (correctly) replace this chip do you think there is a possibility I can save the MCU?
It certainly sounds like you have a good chance. There's always a chance of additional damage, but 'accidentally desoldered a chip' is pretty high on the list of fixable problems (and happens more than any of us would really like to admit).
distraughtmonkey wrote: Fri Mar 24, 2023 1:14 pm Anything else look like I might have hurt it?
I don't see any other components off their pads or showing any obvious signs of damage, so that's hopeful.

The biggest hassle would be having one of the ICs squirm on its pads and need to be realigned. That's not fun even when you're comfortable with SMT rework, but I don't see any evidence of it in the photos above.

Don't worry about the scratches on the back of the board unless close inspection shows they've actually cut any traces they cross. Such damage is unlikely, but fixable.

The worst case, and also the lowest probability of happening, would be for a scratch to smear copper in a way that shorts two traces together. The fact that it's not strictly impossible means that it could be the source of some truly obscure bugs.

Fortunately it's easy to find that kind of short with a multimeter if you know to look for a short in the first place.

For now, tuck the idea away as a low-order possibility and deal with the mechanics of replacing the regulator. That's the next step to accomplish, and leads to the next state that will require testing.

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distraughtmonkey
 
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Re: Can I save my KB2040?

Post by distraughtmonkey »

Mike, thank you so much! I will find myself a regulator and see what I can do to mess this up further ;)

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adafruit_support_mike
 
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Re: Can I save my KB2040?

Post by adafruit_support_mike »

*laugh*

Don't stress too much. Working on damaged boards can be fun if you approach them with light pessimism: they're already dead, and making them more dead is just an excuse for a Viking funeral. Getting them to work is a pleasant surprise, not a realistic demand.

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distraughtmonkey
 
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Re: Can I save my KB2040?

Post by distraughtmonkey »

I wholeheartedly agree. I already have a replacement for this one, it's time to see if I can learn something and maybe, just maybe, have a bonus working board at the end.

I did find some AP2112Ks on Digi-Key for relatively reasonable considering how quick they'll be here.

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distraughtmonkey
 
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Re: Can I save my KB2040?

Post by distraughtmonkey »

Hey Mike, thought you might like to know, I got it working.
Got a fresh voltage regulator soldered on and it's recognized by Via!
Thanks for your guidance.

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adafruit_support_mike
 
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Re: Can I save my KB2040?

Post by adafruit_support_mike »

Awesome! Glad to hear the new regulator was all it needed.

Happy hacking!

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