JRK 12v12 USB voltage regulation

Firstly, thanks for the great support that this forum offers.

I am was having feedback noise problems with on of my JRKs and while trying to track down the problem, I measured the 5v pin only reads 3.7volts. I checked the another JRK connected to the same PC, and 5v pin reads 4.7volts. These readings were same with Vin connected to 12v or Vin disconnected. I tried other USB ports which gave the same results.

The low voltage puts the feedback supply voltage (ie 3.7v) on the minimum supply voltage threshold for my Hall Effect feedback sensors - (which is most likely causing the feed back noise /jitters etc)

Is the USB voltage run through its own onboard voltage regulator?

Is Vin fed through its own Voltage regulator?

I understand that Vin takes priority through a VReg and switching circuit. So, is the onboard Voltage Reg likely to be faulty?


The USB power does not go through the regulator, so if you are measuring 3.7V when powering through USB as well as Vin, then I do not think the regulator is damaged.

Did you have anything connected to the jrk when you measured the voltage? If you did, could you try measuring it with nothing connected (including your hall effect sensors)? I am concerned that you might be drawing too much current from the on-board regulator, causing the voltage to drop.