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Teensy 4.1 tiny power IC replacement, Tips needed (lemmy.ml)

submitted 4 months ago* (last edited 4 months ago) by AbidingOhmsLaw@lemmy.ml to c/askelectronics@discuss.tchncs.de

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I have a project that is using a Teensy 4.1, the cheep 5v regulator I was using in the project let the magic smoke out for no good reason. I replaced that but now the Teensy boots and runs for about a min then quits. There is a TLV75733P power IC that is supplying the 3v3 and it gets hot then quits supplying power. Since that IC is $0.46 vs a new Teensy 4.1 ~ $40 I want to try and replace it. I have done a bit of SMD work but not tried to remove a tiny chip with a GND pad before so I’m looking for any tips. The PCB of the Teensy has header pins so I can’t really get good contact to a hot plate to preheat the board.

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[–] Tolookah@discuss.tchncs.de 4 points 4 months ago* (last edited 4 months ago) (1 children)

Are you sure you replaced the 5v regulator with a pin compatible one?

The tlv75733 is a linear regulator, so if you are giving it more voltage than it was set up for, it will get hot, as it has to soak up the difference.

Does the teensy act the same when powered by USB instead? If not, it's not the tlv.

Edit: the tlv has a thermal shutdown, so the shutdown is a direct result of the overheating.

Follow up edit: https://forum.pjrc.com/index.php?threads/one-component-on-teensy-4-1-gets-very-hot.62255/

[–] AbidingOhmsLaw@lemmy.ml 3 points 4 months ago* (last edited 4 months ago)

Yes, The 5v regulator is the same and it is outputting 5.01v under load and 5.12v no load. Not sure why the first went bad but I’m guessing the POS 5v reg sent a spike on the 5v rail when it went bad and that damaged the TLV75733. The Teensy acts exactly the same connected to a USB unmounted from the board. It boots, runs for a min while the TLV heats up then the 3v3 drops and the Teensy crashes.

[–] Grimy@lemmy.world 3 points 4 months ago (1 children)

You are going to need one of those hot air soldering guns (rework station) I think. You can heat the back with it, it's the only way I know for the gnd pads if you can't use a hot plate or oven.

[–] AbidingOhmsLaw@lemmy.ml 3 points 4 months ago (1 children)

I have one, going to try and tape it off from the other components heat it up and see if that works.

[–] AbidingOhmsLaw@lemmy.ml 4 points 4 months ago

Hey, it actually worked and took less the a couple of min.