Teensy 4.1 and diy-thermocam.net: did I burn something?

C

chrisp

Member
Hi everybody.
I am an absolute newbie in electronics.
I have a Teensy 4.1 used in this project: https://www.diy-thermocam.net/building-instructions/.

I followed the instructions step by step, but since it's my first time using a soldering iron, I must have made some mistakes.
Once arrived at the firmware flash ste, I was unable to upload the firmware, or at least if I did, I didn't do it correctly, as on the first day the board kept flashing and the verbose log of the loader was functioning intermittently. It seemed like I was using a faulty or incorrect USB cable. The Lepton occasionally "closed the shutter", and the screen remained completely white. No other signs of life or connection with the PC.

The next day I wanted to try with a new cable, but the Teensy no longer showed any signs of life, while the battery charged normally and the Lepton occasionally still "closed the shutter".

I'm afraid I may have burned out some components. So I took the Teensy out of the peripheral for some test.
How can I test the Teensy using a multimeter (I have restored the connection between the two USB-VIN power pads)? In particular, I would like to test the "default" functionality of the various components, but I'm not sure what to measure and where. Can you help me step by step? I measured VIN and it's 4.95V, but 3.3V is actually 0.16V.
Could the regulator have burned out? What else can I measure and where?

I tried with a new DATA cable, I examined the board at 20X but i did'nt notice anything except for a lot of fluxant, I'm waiting for isopropyl alcohol to arrive in order to clean flux on the board.

I read similar threads:
but actually I cant' tell if it is the same situation.


Thank you in advance
 
Google wants a login just to view. :(

You can put pictures into your message here. It's easy. Just select the image in any graphics program and Ctrl-C to copy. Then here on the forum, Ctrl-V to paste.
 
I can see your pictures and your soldering looks reasonable. Cleaning the flux off might help identify if there is a solder whisker somewhere that the flux is masking.

If you are getting 0.116V with the Teensy 4.1 no longer in the system and there is no solder short, then It sounds like your 3.3V regulator is probably burned out. If the 3.3V is being used to power other items in the system, I would look in those areas for possible shorts as well.
 
PaulStoffregen said:
Google wants a login just to view. :(

You can put pictures into your message here. It's easy. Just select the image in any graphics program and Ctrl-C to copy. Then here on the forum, Ctrl-V to paste.
Click to expand...
Thank you for the advice.
Here are the pictures:
 

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KenHahn said:
I can see your pictures and your soldering looks reasonable. Cleaning the flux off might help identify if there is a solder whisker somewhere that the flux is masking.

If you are getting 0.116V with the Teensy 4.1 no longer in the system and there is no solder short, then It sounds like your 3.3V regulator is probably burned out. If the 3.3V is being used to power other items in the system, I would look in those areas for possible shorts as well.
Click to expand...
I know it is very probable. A replacement board is arriving, however, just to be sure, I would like to measure the tension out of the regulator: which pin(s) should I measure? (regulator is U4 right?)
Then I will also double check solderings in the thermocam PCB. I would also discover the cause of the burning, in order to avoid another accident for the same reason.
Thank you! :)
 
The test point by 5V has what looks to be a generous Flux pile and a solder splatter? Not sure what is 'there' it might influence.
1737236756687.png
 
Yes, it is, flux plus a drop of solder.
As soon as I have isopropil I will clean and remove solder, but it doesn't seem to short anything...would it?
 
BTW - nice pictures!

Looking again at the snippet - there seems to be a flake in the flux toward the "G"nd pin that isn't silkscreen.

Funny a cold solder joint won't connect - but have to worry about flux and debris ...
 
chrisp said:
Yes, it is, flux plus a drop of solder.
As soon as I have isopropil I will clean and remove solder, but it doesn't seem to short anything...would it?
Click to expand...
Flux can vary in conductivity I suppose. Extra flux around PSRAM chips on QSPI has been behind failure until cleaned.
Also that test point could be 'anything' - no top trace to a simple nearby pin - Paul would know - but a direct influence across flux could be meaningful.
 
For building a DIY Thermocam with a Teensy 4.1. The screen is white, the board flashed before, but now it’s unresponsive. VIN is 4.95V, but 3.3V reads 0.16V. Could the regulator be damaged? How can I test the Teensy and fix the white screen issue?
 
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