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fried my second pi zero - no idea whats wrong!
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fried my second pi zero - no idea whats wrong!

by ikolino on Tue Aug 20, 2019 12:29 am

Here is a picture with the setup.
https://imgur.com/a/FysfTCH

- pi zero W (https://www.adafruit.com/product/3400)
- zero2go omini (https://www.adafruit.com/product/4114)
- tft lcd screen (https://www.adafruit.com/product/911)

I have to power the zero2go and the LCD screen.
When i connect everything to AA batteries (4xAA, 6v) it works great.
When i connect everything to a 12v marine battery, the pi zero just dies. I can tell its the pi zero because it gets very hot, and i can smell something burnt.
The LCD screen and the zero2go omini still work though! (?)

At every step of the way, I touch everything with a multimeter and I always get the expected voltage and polarity.

I am at a loss because the thing that dies is the one that is not connected to power?
Anyone know what could be wrong?

ikolino
 
Posts: 2
Joined: Tue Aug 20, 2019 12:19 am

Re: fried my second pi zero - no idea whats wrong!

by adafruit_support_mike on Wed Aug 21, 2019 12:35 am

What's providing the 12V power?

adafruit_support_mike
 
Posts: 58799
Joined: Thu Feb 11, 2010 2:51 pm

Re: fried my second pi zero - no idea whats wrong!

by ikolino on Wed Aug 21, 2019 1:27 pm

It's a 12V deep cycle battery.

I've since found the problem: as I was wiring things, I had connected positive (live) to the LCD without connecting ground first.
That way, the composite cable was acting as ground for the LCD and some current was flowing "backwards" into the Pi from there, and that fried it.

I've wired things correctly now and it works. Lesson learned. :)

ikolino
 
Posts: 2
Joined: Tue Aug 20, 2019 12:19 am

Re: fried my second pi zero - no idea whats wrong!

by adafruit_support_mike on Thu Aug 22, 2019 1:10 am

Glad to hear you found the problem.

"Always connect GND first" is a major principle of circuit construction, second only to "always double-check to make sure you haven't swapped VCC and GND."

adafruit_support_mike
 
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Joined: Thu Feb 11, 2010 2:51 pm

Please be positive and constructive with your questions and comments.