AQ6 makes Magic smoke - Phoenix rises from ashes

[jabram]

Thanks Steve,

You've convinced me to stick with the 2 x RECOM.

Joe

[jabram]

Two new RECOMs arrived today from element 14 in Sydney, installed them using thin automotive trim double sided tape.





I am willing to bet that someone when laying out the AQ6 PCB forgot to leave adequate ground relief around the ground pins for the RECOM, particularly the one near the I2C socket, it takes a lot of heat to melt the solder on the GND pin for the RECOM a LOT more than what it should take, I know it is a large GND plane but nevertheless, I bet there is no GND relief on those pads, this needs to be rectified in future versions of AQ6 PCB as it already has and will lead to further soldering issues for the RECOM pins, same issue with GND pin on the power connector.

Anyway, my AQ6 is alive and I am back in the beta testing.

Did the first static calibration curves look good, only problem is it is winter here in Australia and down in my basement it is cold, about 6C so after 100 minutes the small insulated food container only got up to 35C which is not hot enough since the places I plan to use this run 45C in the shade. I will do them with the sun warming up the food container tomorrow.



An observation, the 2 new RECOMs seem to me to be running cooler, the old ones when left on the bench switched on for over an hour they got fairly warm, the new ones are running cooler after being switched on for over an hour.

[chris24g]

if you need your board to get warmer, wrap it in some antistatic bubble wrap. i was able to get just over 50C.

[GoFaster]

Good idea to insulate it further in a small air space. Isn't antistatic stuff conductive, even if at very high resistance?

[jabram]

[kinderkram]

Congratz!

The board looks like brand new. From the first glance I thought it was totaled.
Can't figure out why the new Recoms are cooler, though.

[rput]

I feel embarrassed to admit it, but I also reversed polarity and got the stinky smoke from the Recoms This is really stupid, especially after all the warnings in the documentation. I blame myself, as I used black heatshrink on both GND and V+ on the input connectors and this led me to my mistake somehow. After connecting the battery there was a hissing sound like a boiling kettle and then a strong smell. By the time I disconnected the batterry there was molten plastic bubbling from the RECOMS and a toxic smelling smoke.

After my initial depression, I figured I should try and see if the board is salvageable. I removed both Recoms and applied a regulated 5V output from an Arduino Mega board to both output connections from the Recoms (together with the gnd). Unfortunately this did not resuscitate my board. Is there anything else I can try? Is there any way to test and see if the MCU is still functioning?

Thanks for your help everyone, I was just getting excited to learn the calibso, but I guess I will have to wait.

Richard

[kinderkram]

Hi and welcome to the show!

Shit happens even to the best and I'm sure someone will help you out if you can't manage it on your own.
As you can see in this thread Jabram managed to get his board working again - so there's still hope.
Unfortunately Joe removed all the pics in anger after it burnt for a second time.

As far as I remember he only replaced the Recoms but can't tell for sure. Maybe some other parts are damaged, too.
Where are you located and where did you get your board from?

Just wait for one of our experts jumping in...

Norbert

[JussiH]

Not good!

What usually happens apart from burning the Recoms, is that an internal power trace in the board is burnt too. This can however (In some cases) be dealt with by placing a wire jumper from Vin+ to the input pin of the Recom right next to Vin. Start by verifying continuity and resistance between Vin+ and the input pins on the recoms.

Damage depends on how long you had the reversed polarity on and the voltage/current potential of that source. If left on for more than 1 second it will burn out parts of the internal groundplane and that is really bad news for reliable operation. If that is the case, then I would not recommend trying to revive the board.

[rput]

Thanks for the quick replies!

I am in Canada, ordered through flyduino I believe. Hard to tell how long the power was on, it seemed like forever... There is continuity between the Vin+ and the Vin of both Recoms, I hope that is good news.

What else can I check for?

edit: I bought it through viacopter.