Could I repair a Beaglebone Black that had was fried by the wrong adapter?

[jayfehr]

As it turns out the Beaglebone Black has no protection circuitry between the USB plug and the board. While using a powered USB hub I had both a 12V and 5V cable sitting next to each other. I accidentally grabbed the wrong one and, well, now I'm down a BBB.

I was curious if it would be possible to find the exact component that died and replace it? Well of course it's "possible", but is it realistic? If so any tips on where I should start looking? Nothing on the board is visually damaged and there was no smoke. When I plugged in the adapter it just stopped, and of course didn't start up again.

Thanks in advance.

[kolonelkadat]

there is no reason you couldnt try replacing the TPS65217C power management ic. with any luck you blew that before any of the bga chips were damaged.

but at whatever like 10 bucks in one off quantities for the pmic, the 45 dollar beaglebone is probably beyond economical repair.

[jayfehr]

You're absolutely correct. The cost isn't really a concern. I am more interested in the learning aspect. If you're going to learn how to diagnose and fix issues like these a $45 machine is better than a $2000 machine.

Would their be a way to test that part before blindly purchasing? I've never attempted to fix something like this before so any advice would be good advice. My brother also has a three year old 1080p TV that I was hoping to fix too at some point. So directions more in the realm of how to learn as opposed to how to fix would be preferred. But all are welcome.

[jayfehr]

Thanks for the replies. I'll poke around at it with a multimeter this weekend. But you're probably right, it most likely isn't worth fixing.

Also I see I forgot to reply about the LEDs. No, they do not turn on. The board is effectively dead right now.

[jayfehr]

It'll cost $20 to get that chip shipped to me. Yeah, I'd be better off putting that money towards a new BBB.

Thanks for all the replies.

[max666]

I don't know how many power rails the Beaglebone Black has, but trying to power it up from external power just for kicks, might be fun for you.

About the old 1080p TV; look for bad caps. Dave also has some Monitor/TV fixing vids.

[amyk]

Given that the PMIC's input is specified for an absolute maximum of 20V and the datasheet (page 36,37) explicitly specifies that it has OVP, I'm more optimistic that it is still OK given that you only applied 12V to it and it's connected in a configuration that supports OVP. The capacitor C2 is only 10V rated, I would check to make sure that one hasn't failed short. You can follow the datasheet and the Beaglebone schematic and check its operation.

The power LED is driven from the 2nd LDO which doesn't turn on by default.

[nardev]

I did something similar.

I accidentally plugged 12V instead of 5V and now, it works only if powered through USB.

Wondering, if it is ok or not...

Also, when i attach 5V now and if i measure voltage on the board it shows around 1.7V..


any ideas? Is it broken or not???

[JacquesBBB]

You probably have a short cut. This is why the voltage drops to 1.7 V instead of 5V.

In similar experience, I  checked for short cuts.  Look to the circuit path for power, and removed
components until I found the culprit, each time testing for shortcuts.

It was indeed the main CPU which was fried.

The problem was then to replace it  and  to reload the firmware.

[nardev]

You probably have a short cut. This is why the voltage drops to 1.7 V instead of 5V.

In similar experience, I  checked for short cuts.  Look to the circuit path for power, and removed
components until I found the culprit, each time testing for shortcuts.

It was indeed the main CPU which was fried.

The problem was then to replace it  and  to reload the firmware.

Well i was lucky this time, it was the psu plug which was not fitting 100%.. although before that i checked all capacitors.. because they have 10V limitation and the PSU chip is actually 20V max.

It works fine now

thnx

[SparkyBruce]

I too have seen the TPS65217C survive 12V on the input on one of my designs.

The AM335X that it powers is far more sensitive to it's supply rails and I have killed one with 5V connected through to the 3V3 rail.

I probably have some TPS65217C's kicking around at the office (One of the benefits of being a Ti Design Network partner in addition to being taken out for lunches..). I will have a quick look tomorrow.

They are easy to put down with hot air.

Bruce