Teensy++ 2.0 3.3V question

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7951

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So I soldered the 3.3V regulator to the Teensy++ 2.0 and cut the trace between ground and 5v but my voltmeter shows that the pads are still connected.
I cleaned the cut and inspected it, I'm pretty sure that nothing of the trace is left. Is the trace deeper than I thought or do I've fallacy?

I don't have a camera nearby so I can't take a picture of my Teensy, but the solder only connects the 3.3V and the ground pad and the cut is like 1mm deep.
 
I do not know. I can't see the board, or your multimeter, or even specifically what you're doing to make this measurement (volts, ohms, powered or unpowered board, etc)
 
lAoxbht.jpg

The light blue line is the cut, grey is solder and red and black are the multimeter headers.

The board is unpowered and the multimeter is set to ohm. It shows 0 ohm so it's directly connected somehow.
My soldering is pretty clean so the solderblob doesn't touch the 5v pad anywhere.
 
I just tried it here on a Teensy++ 2.0 which was modified for 3.3V. I've used this Teensy++ in *many* projects... as you can see from the signs of wear)!

3v.jpg

Not sure if this photo helps much, but I just don't know what else I can do to help.
 
Alright, thanks for the picture. So it's normal that the 5v and the ground pad are connected.
I was confused, since I thought the purpose of cutting the trace is to disconnect them from each other.
I'll try to work with my Teensy now. Thanks for your help. :)
 
7951 said:
Alright, thanks for the picture. So it's normal that the 5v and the ground pad are connected.
I was confused, since I thought the purpose of cutting the trace is to disconnect them from each other.
I'll try to work with my Teensy now. Thanks for your help. :)
Click to expand...

Well, you will always have some resistance in a power supply on a circuit. That's 929000 Ohms on his meter, which is really really small, its probably reading the capacitors in the circuit.
 
Hello,

I have the same problem, i cut the trace to 5V and soldered to 3.3V , soldered my 3.3V regultor and connected the USB and somehow I get 5V in the 5V pinout (multimeter mesure)
I´m 100% sure the trace is cut but I still get connection between 5V and the middle pad, or the USB Vin pin and the 5V even I cut the connection.

First i thought something was wrong with the regulator, so i tried outside the teensy and it works well, I get 3.3V from output.

I removed the regulator keeping the 3V soldered and I still get 5V when connected via USB, I should n´t get any voltage if I read correct the schematics. It seems that there is some defect in the PCB or something else.

Is this common issue ? Is there any solution to my problem.

The only solution i see to use the teensy++ 2 in 3.3V is to just cut the 5V from USB cable and connect a 3.3V external supply ? Or maybe keep the 5V pad connected so I have 3.3V in the UVCC and VBUS ?

Regards and thank you
 
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