I rarely test unbalanced devices on my bench. I have a consumer stereo preamp that a friend asked me to look at. RCA In and Out. Two prong AC power cable. The shell of the RCA cables is connected to chassis. No chassis connection on the power cable.
I set up the Portable One as described in the manual. I made cables that have RCA tip to XLR pin 2 and RCA shell to XLR pin 3. Shield is connected to XLR Pin 1 with NC on the RCA connectors. The Portable One Generator is set to 40Ω Unbalanced. HiZ Input.
I was getting very strange results. It was like it wasn't grounded. When you touched the device there was static discharge and tons of 60Hz hum. I didn't believe what I was seeing was true so I pulled out a "bump box" bi directional -10dbV to +4dBu type thing. Electronically balanced. When I put that between the DUT and the Portable One everything behaved as I expected.
What's going on?
I set up the Portable One as described in the manual. I made cables that have RCA tip to XLR pin 2 and RCA shell to XLR pin 3. Shield is connected to XLR Pin 1 with NC on the RCA connectors. The Portable One Generator is set to 40Ω Unbalanced. HiZ Input.
I was getting very strange results. It was like it wasn't grounded. When you touched the device there was static discharge and tons of 60Hz hum. I didn't believe what I was seeing was true so I pulled out a "bump box" bi directional -10dbV to +4dBu type thing. Electronically balanced. When I put that between the DUT and the Portable One everything behaved as I expected.
What's going on?