Blown up my Pi with 19V input

[stevetl]

I think I've bricked my lovely new RPi. My strange power supply has a 19V output and a 5V output. Pi was working OK, but this morning I realise I've plugged in the 19V input by mistake, and now its not.

Now I get a steady read power on light but no other signs of life. Can anything be done? What component would I have destroyed?


thanks

stevetl

[Joe Schmoe]

I thought there was stuff in place to cover for this - isn't it supposed to blow a fuse or trip a regulator or something in an over-voltage situation?

P.S. I've read that it might not work with a minimal over-voltage (like, say 6V), but that it would definitely work with a large one (like your 19V). Am I wrong?

[Grumpy Mike]

Well there are regulators on the board to cut the input voltage down to the required lower voltages of 3V3 2V5 and 1V8. So directly you could have blown anything connected to the +5V line which is anything plugged into the USB sockets or the HDMI socket.
However, with such a large voltage it is likely that you have blown up the regulator's input capacitors at least.
There is a TVS diode ( Transient Voltage Suppression ) on the input that is supposed to conduct when over voltaged and allows the excess current to blow the input poly fuse. However, this is for transients and it looks like you might have blown something else as well.

What test equipment do you have?
Apply the correct voltage and check what you get on TP1 & TP2, if that is down then you could try replacing the poly fuse and TVS. Then check the output voltage of the three regulators. If these are showing at over their regulating voltage then you have blown most of the chips and possibly also the SD card.

[Vindicator]

My question would be have you seen the magic blue smoke that took your device's soul to the gods.

[stevetl]

Thanks everyone. Voltage across TP1-TP2 is 4.95V. (I have a DVM).
Can you point me at a diagram showing the regulator output voltages? Is TP1 0V?
The SD card seems to be OK (at least my netbook reads it fine).
They must have invented polyfuses since I studied electronics - can you point me at an idiots guide?

[stevetl]

There wasn't any smoke, sparks or bangs. But I know that ICs sometimes " go gentle into that good night".

My question would be have you seen the magic blue smoke that took your device's soul to the gods.

[godFather89]

But I know that ICs sometimes " go gentle into that good night".

Yes, but it's unlikely at 19V.

So the voltages on all the regulators are fine?

[NickT]

Thanks everyone. Voltage across TP1-TP2 is 4.95V. (I have a DVM).
Can you point me at a diagram showing the regulator output voltages? Is TP1 0V?
The SD card seems to be OK (at least my netbook reads it fine).
They must have invented polyfuses since I studied electronics - can you point me at an idiots guide?

Schematics are at http://www.raspberrypi.org/wp-content/u ... s-R1.0.pdf.

The datasheet for the protection diode is at : http://www.farnell.com/datasheets/89307.pdf - so your maximum voltage applied to the chips should have been clamped to some extent.

[Grumpy Mike]

They must have invented polyfuses since I studied electronics - can you point me at an idiots guide?

Try:-
http://en.wikipedia.org/wiki/Resettable_fuse

[tna]

To revive what is in Internet time an ancient thread, I seem to have done the same thing to my Model 1 B with a 12V instead of a 5V input (due to my rushing to assemble an input supply with a12V battery and a DC/DC converter) and have the same symptoms when I now connect it to a power supply: PWR LED on, nothing else happens.

Steve, did you manage to do anything about it? Not that it's a big deal to buy a new one, but still, it'd be neat if I could get it working again, I don't know, with a new diode and a bit of soldering or something like that...

Just to provide the full context, this is what I was able to measure:

- TP1 to TP2 voltage is a healthy 4.9V on a short USB cable from a smooth (battery) source
- this would suggest that the D17 diode didn't burn up (http://tinyurl.com/jkf85uq)
- this voltage is puzzling because a sole red light is supposed to mean inappropriate voltage or an unreadable SD card (http://tinyurl.com/mkgztq3), but the card is readable on my laptop, and the voltage is fine
- the F3 polyfuse seems to be fine, which is bad news, because it suggests something else burnt up before it could activate itself (https://www.safaribooksonline.com/libra ... /ch01.html)
- voltages on C11, C15 and C9 should theoretically be 3V3, 2V5 and 1V8 and I measure 3V28, 2V47 and 1V78, so I think there's nothing obviously wrong there

[jdb]

If you supplied 12V to a Pi from any decent power supply, that Pi is dead.

The polyfuse/suppression diode combo is implemented to protect against the side-effects of overvoltage, not the primary effects. The fuse is generally slow to react to overcurrent (it's thermal-only with no electronic/magnetic trip) and with a substantial fault current flow, the admitted downstream voltage is likely to be well in excess of the threshold breakdown voltage of the suppression diode. In an overvoltage situation where the upstream supply can deliver more than a couple of amps, the protection devices on the Pi will not act to protect function, only safety.

It's the difference between "board burst into flames after I overvolted it" and "board doesn't work after I overvolted it".

[stderr]

It's the difference between "board burst into flames after I overvolted it" and "board doesn't work after I overvolted it".

Basically added to avoid people making high hit count youtube videos.

[stevetl]

Sorry tna - I came to the same conclusion that has been reached here - an overvolted Pi is an ex-Pi, and procured another one.

[calleblyh]

I have experienced similar problem, not 19V but 12V. I placed the RPi in my fridge over nigth and next morning it was ok. Good luck