My Powerboost 500c stopped working


#1

Hi all,

I’m new to the forum so nice to meet y’all. I have an adafruit 500c powerboost since february and I absolutely loved it! I think there is no better option for portable projects when you want to have the option of charging them.

So yesterday it stopped working…and I’m not sure why. I was trying to fit a sliding switch between the BAT/EN/GND pins. It might have to do with the fact that it’s a 3 state switch (rather than 2 state) and it shorted some pins it shouldn’t? I may have heard a “POUF” sound go off but it may be my imagination. Could it be a capacitor that blew up? Can I find it? Is there some common component that blows up on the powerboost? Any help to revive my beloved powerboost would be much appreciated!!

PS: I have already ordered 2 more to come but I still need to fix this one!

EDIT: Oh some important detail I left out. When I connect the LiPo battery now I the LEDS (PWR - LOW) light for a millisecond and then go off. It cannot be the battery’s fault because I checked with other batteries and it does the same.


#2

The datasheet for the TPS61090RSAR chip on the Powerboost can be found here: http://www.ti.com/lit/ds/symlink/tps61090.pdf

And the schematic here: https://learn.adafruit.com/system/assets/assets/000/017/555/original/adafruit_products_powerboost500C.png?1403289316

Looking at both, I don’t think there’s anything you could have done except, perhaps, short VBAT to GND which might potentially have fried the TPS61090RSAR. While you could replace it, actually getting hold of the part would be costly and replacing it would be difficult without a hot air station and lots of patience.

Alternatively you could have blown the LIPO charger IC, which would be a little easier to replace physically, you could try picking one up and give it a go if you want to experiment: http://uk.farnell.com/microchip/mcp73831t-2aci-ot/li-ion-li-poly-charge-controller/dp/1332158

So, in answer to your question- yes, but unfortunately the components that blow up on things like this are generally the most expensive and difficult to replace.

Good luck, and post your results if you give it a go! It’ll be a learning experience and a challenge if nothing else.


#3

Thanks for the tip! I think I will try to replace the MCP and see what happens…


#4

On second thought… Since when I plug the charge cable (microUSB) the LEDS light properly, would that mean that my charging circuit works fine? Or is it that the LEDs would turn on regardless of the MCP being fried?


#5

The wiring around the Stat LEDs in the schematic is a little weird- it uses a multiplexing trick. From the looks of it, when you connect a USB cable then both the Orang and Green LEDs should turn on briefly until the charging IC fires up and sets a HIGH/LOW state on the Stat line.

Current would flow through the Orange LED, through the 470ohm resistor, through the 1K resistor, through the Green LED and to Ground.

However if the IC sets Stat HIGH then only the Green LED should light up, and if it sets it LOW then only the Orange LED should light up.

I’d guess if either the Green or the Orange LED lights up on their own, then it’s possible that the IC is still alive, but it’s also possible that only a portion of it is fried and the rest of it being alive isn’t much help.

Without actually testing it, I can only speculate!