Joulescope Losing USB connection on measurement

Likely user error.

Was recording I/V/P using joulescope yesterday without issue.

Today when I attempt to measure current only, the sensor status LED switches to flashing red and blue for 5ish seconds, 1 green blink, repeat as long as joulescope is connected. The rear Controller LED status is green, then switches to blue at the same time as the joulescope disconnects, playing the windows device disconnected audio sound.

Joulescope is dropping communication when I attempt other measurement setups as well.

Is there a recent software update or a setting I changed? (I did hit reset to default hoping it would fix). Do I need a specific USB Driver for reliable operation?

Did I toast my joulescope? Or am I missing something?

toasted a sense resistor, will solder on replacement and hope

Hi @StratoJoe - Sorry to hear that your Joulescope is losing the USB connection! We have not had any recent updates that would affect USB behavior.

I am presuming that you are using a JS220 since the sensor status LED is RGB.

If you aren’t already, try connecting your Joulescope directly to a USB port on the host computer, no USB hubs, docks, or adapters. Neither the JS110 or JS220 are compatible with unpowered USB hubs, and even some powered USB hubs cannot provide the full power requirements. Also, some USB hubs are not as reliable.

Does this help?

Uh, oh. If a sense resistor was toasted, it’s corresponding selection MOSFET likely was also toasted. They tend to go together. Also, replacing a sensor resistor will definitely knock your JS220 out of calibration.

We are working on the software-controlled fuse feature which includes protection for the JS220. You were a little to eager to test this feature out :wink: Still a work in progress, but here is what it looks like:

Thanks for your response, I did some investigation and found a burnt resistor on the joulescope pcb, user error.

Do you happen to know the resistor value of the resistor immediately to the left of R27?


Haha, that fuse feature would have been nice.
Unfortunate to hear that the mosfet was likely also toasted, I’ll attempt to replace that as well if i get that far.

That resistor is 0.01 Ω. We use CRF0805-FZ-R010ELF.

I also sent you a DM here to see how we can get this fixed.

You can download UI 1.0.35 (currently beta) here. This release contains the fuse feature, and updates the JS220’s FPGA gateware and firmware. This automatically protects the JS220 and should prevent most overcurrent damage. You can also set your own fuse thresholds to protect your attached equipment. Here is a screenshot showing the completed feature: