Author Topic: I broke my CurrentRanger... suggestions for repair? [FIXED]  (Read 351 times)

josh

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Oops, I did the FIRST thing on the "But itís not OK:" section of the instructions: https://lowpowerlab.com/guide/currentranger/safety-and-proper-usage/

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"to measure a DUT that is mains/earth powered/connected, with an oscilloscope/DMM that is also mains/earth connected. Depending on the range and opamp biasing mode in use, this can cause ground looping and can damage the CurrentRanger"
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I did exactly that. My power supply and O-scope were both mains/earth connected and now my CurrentRanger does not power on (green LED shows for 3 seconds and then goes out).

Any suggestions for repair? Is there a particular part that gets fried in this situation.

Thanks for your help, this is a great product and I think I'll stick to wireless connection after this!






« Last Edit: June 04, 2019, 03:09:53 PM by Felix »

Felix

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Re: I broke my CurrentRanger... suggestions for repair?
« Reply #1 on: May 16, 2019, 12:09:10 PM »
Oops, I did the FIRST thing on the "But itís not OK:" section of the instructions: https://lowpowerlab.com/guide/currentranger/safety-and-proper-usage/

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"to measure a DUT that is mains/earth powered/connected, with an oscilloscope/DMM that is also mains/earth connected. Depending on the range and opamp biasing mode in use, this can cause ground looping and can damage the CurrentRanger"
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I did exactly that. My power supply and O-scope were both mains/earth connected and now my CurrentRanger does not power on (green LED shows for 3 seconds and then goes out).
Yup, that will break it, and it's good to read that section from the guide, if nothing else. A bummer for sure :'(

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Any suggestions for repair? Is there a particular part that gets fried in this situation.
Hmmm. It probably took down the MCU, possibly opamps, maybe Charger/LDO and inverter chip. Those are unfortunately some of the most expensive and difficult to replace parts on the board, especially the MCU. If you have HOT plate and/or HOT air then it's not too bad but you have to be pretty good or you can lift pads and such. Reflashing the MCU with bootloader requires an Atmel ICE programmer and soldering to a few key points on the board for SWD interface.

OR ... I can attempt to fix it for you. I would charge component cost + repair fee (because I know this will not be a quick fix). If you'd like, you can return this to me for analysis and see what it will take to fix. Let me know.

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Thanks for your help, this is a great product and I think I'll stick to wireless connection after this!
You don't necessarily need wireless. You just need to really be careful not to introduce a current path or ground loop through the board's internal circuit. You can have an earth grounded scope at output, but then keep the INPUT and USB completely isolated from mains earth/ground. That way there's no possible current path from input/usb to output or vice versa.
Then indeed you have the Bluetooth option to take wireless readings.

PS. Would anyone care for ... RFM69 wireless instead? Would that be Woot or what!

josh

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Re: I broke my CurrentRanger... suggestions for repair?
« Reply #2 on: May 16, 2019, 01:21:22 PM »
Thanks for the quick reply! Yes, I promise I read the instructions and have been using your product for several months! I think I didn't drink enough coffee this morning, spaced out a bit and forgot to use the isolated scope.

I think I'll ship it back to you to take a look. I'll send you a PM.


Felix

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Re: I broke my CurrentRanger... suggestions for repair?
« Reply #3 on: May 18, 2019, 08:57:35 PM »
josh,
Thanks for your return,
Although there were no visible signs of damage, the SAMD21 chip was dead. It was internally shorted between 3.3V to GND.
All other parts were OK and replacing and reprogramming the SAMD21 brought it back to life.
Once this is back in your hands, if you're satisfied with the service please leave some follow up feedback here.

ChemE

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Re: I broke my CurrentRanger... suggestions for repair?
« Reply #4 on: May 19, 2019, 05:09:19 PM »
I mean, who else supports a product like this?!  Felix is awesome!

josh

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Re: I broke my CurrentRanger... suggestions for repair?
« Reply #5 on: June 04, 2019, 11:56:44 AM »
@Felix - thanks so much for the repair. All is well and I really appreciate your help. Thanks again!

Felix

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Re: I broke my CurrentRanger... suggestions for repair?
« Reply #6 on: June 04, 2019, 03:09:45 PM »
My pleasure  ;)