I bought a DC power supply on ebay from a seller who customizes them and asked them to use a 4-pin XLR at the cable end of the output, with pin1=GND and pin4=5v (that's what the input of the device I want to power says at the back). The PSU has the right specs for my device, but when I connected it and turned it on, my device didn't power up.
Looking at the back of the PSU, the cable is coming out of a coaxial socket with "+" in, "-" out, and I started suspecting that the "-" hadn't been wired to the chassis ground as I expected (perhaps mistakenly, but I don't know any better). I brought out the voltmeter and surely enough, both read 5v (pin1 and pin4). Also checked that the used XLR pins correspond to the "+" and "-" of the coaxial plug - all good there. I hope my device hasn't been damaged. Please correct my logic if I'm off the mark.
Opening up the PSU, the coaxial output's terminals are clearly visible, as is a chassis ground further down the PCB (I'm presuming that's a chassis ground because it's standing by itself on the PCB without any traces around it, and a screw attached underneath it that's fixed to the chassis). My instinct is to desolder the coaxial socket's "-" from the terminal on the PCB, and use a short insulated cable to connect the socket's "-" to the chassis ground (not the AC socket ground). How wrong am I?
Thanks guys!
Looking at the back of the PSU, the cable is coming out of a coaxial socket with "+" in, "-" out, and I started suspecting that the "-" hadn't been wired to the chassis ground as I expected (perhaps mistakenly, but I don't know any better). I brought out the voltmeter and surely enough, both read 5v (pin1 and pin4). Also checked that the used XLR pins correspond to the "+" and "-" of the coaxial plug - all good there. I hope my device hasn't been damaged. Please correct my logic if I'm off the mark.
Opening up the PSU, the coaxial output's terminals are clearly visible, as is a chassis ground further down the PCB (I'm presuming that's a chassis ground because it's standing by itself on the PCB without any traces around it, and a screw attached underneath it that's fixed to the chassis). My instinct is to desolder the coaxial socket's "-" from the terminal on the PCB, and use a short insulated cable to connect the socket's "-" to the chassis ground (not the AC socket ground). How wrong am I?
Thanks guys!
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