I’ve burnt some of this product https://www.pololu.com/catalog/product/2120 trying to step down from 7.4V to 3.3V. The 7.4V is made up of two 3.7V Polymer Lithium Ion - 2000mAh Batteries https://www.sparkfun.com/products/8483. Can someone tell me what I have done wrong?
Thanks.
If you would take the time to tell us what you’ve done, describe what actually happened and post a photo or schematic diagram of your entire circuit, perhaps someone would be able to help.
Hi Jim,
Thanks for the response.
I only set up a simple connection trying to measure the output voltage using a multimeter.
It didn’t burn immediately after the set up – only started when I adjust the potentiometer’s shaft to decrease the VOUT. Sorry not able to tell what exact voltage of the measured VOUT was when the fume started. But I’m sure not lower than 5V.
A drawing of the setup has been attached.
Thanks
s.
Hello.
With the setup you described, I would not expect the regulator to fail. Is it possible that you accidentally created a short by bridging power and GND with your screwdriver or test leads? Also, can you post pictures of your setup that show your electrical connections?
-Jon
Hi Jon,
Please find attached a picture of the setup.
The test points (positive and negative) are at some distance apart from each other.
Thanks
s.
Hello.
I don’t see any problems with your setup. Is it possible that your screwdriver shorted something on the board while you were adjusting the potentiometer? In your first post you mentioned that you “burnt some of this product”. Does that mean you have more than one? If so, how many S8V3A regulators do you have, and how many of them are not working?
-Claire
Hi Claire,
Three regulator boards – two burnt and a brand new.
I used a very small screwdriver as seen in the attached.
I’m going to set up the brand new one and see how it goes.
Thanks,
s.
Hello,
Just to let you know that I’ve tried out a brand new S8V3A board and this time there’s not a problem.
I must have shorted the two previously boards by accident.
Thanks everyone for helping.
s.
Since two regulators have been damaged, I am worried that there still might be some problem with your setup that I did not see in the picture. Before testing the last one, could you move your setup to a different location or you breadboard and double check that your multimeter is set to measure voltage? Also, could you try testing the new regulator one step at a time so if there is a problem, we can try to determine at which step it fails? First, just apply power and see if it works without burning. Next, try connecting the multimeter (what voltage do you see?). Lastly, try turning the potentiometer in small increments.
-Claire
Hi Claire,
I’ve tested it again according to your advice by resetting up a new test circuit on a different location of the breadboard. Then applying a very small amount of power in and measuring the VOUT (just below 1V), this was fine.
Next turning the potentiometer shaft clockwise gradually to measure a series of VOUT values:
~1.5, ~3.3, ~4.5, ~7, ~ 8 and ~9. These steps went well.
Then I fully turned the potentiometer shaft anticlockwise intending to repeat the steps above.
Right after this step, a problem occurred. The S8V3A didn’t give out any voltage values.
And no matter the measurements were made on any points in the circuit (i.e. VOUT and GND; VIN and GND; or at the battery’s ‘+’ and ‘-’ plugs) there were no voltage values given unless the S8V3A was taken off the breadboard – it was when I could see 7.4V of the battery again.
All steps have been repeated extensively since yesterday. Still no lucks.
Could you suggest if there are other testing processes I should try?
Thanks,
s.
Thank you for trying those tests. We have not heard of any similar problems with this regulator and have no explanation for the failures you are seeing, but we will try to replicate your results. In the meantime, we have some newer step-up/step-down regulators with better performance that you might consider using. Depending on what output voltage you need, our S7V8A might work. As for the three damaged regulators, if you email us directly with your order information, we can see about getting you replacements.
-Claire
I was not able to get any of the regulators that I tested to break by just turning their potentiometers. However, when I tried shorting various components around the potentiometer with my screwdriver I found that shorting the pins along the side of the IC closest to the potentiometer immediately damaged the board. The regulator IC is not too close to the potentiometer, but an unlucky slip of the screwdriver might cause it to short those pins. If you think that might have happened, I recommend making sure that your screw driver is an appropriate size. Using one with a head that is too large usually increases the chance of it slipping out of place.
-Claire
