<html><head><style>body{font-family:Helvetica,Arial;font-size:13px}</style></head><body style="word-wrap:break-word;line-break:after-white-space"><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div> <br> <div id="bloop_sign_1532049903892278016" class="bloop_sign"></div> <br><p class="airmail_on">On July 17, 2018 at 10:55:56, Jeff Frontz (<a href="mailto:jeff.frontz@gmail.com">jeff.frontz@gmail.com</a>) wrote:</p> <div><blockquote type="cite" class="clean_bq" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none"><span><div><div></div><div><div dir="ltr">I'm not an EE, but it seems like your momentary "dead short" is a cap charging (one perhaps intended to smooth out spikes/sags from cheap wall warts).</div></div></div></span></blockquote></div><div><div><br></div></div><div><blockquote type="cite" class="clean_bq" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none"><span><div><div><div dir="ltr"><div>And I think you want to measure your wall-wart's output with a load on it (otherwise, it seems like the circuitry could be hunting around to figure out what is really required downstream).</div></div></div></div></span></blockquote></div><p>I was about to give up and chuck it when for some reason I started wondering if the board’s problem was not enough current. My bench power supply has a knob for current and one for voltage. When I turn the voltage knob, the little display immediately reflects my change to the output voltage.</p><p>When I turn the current knob, usually nothing happens. So I rarely mess with it. Up until now, I’ve never had to. I know there’s such thing as “constant current” but I’m not sure what it is and I don’t think I can select between CC and CV, at least on this PSU.</p><p>I gradually turned up the current, and lo and behold the switch started going through its startup diagnostics. It was pulling a little under 1A. The switch’s power supply is rated for 2A. I plugged that busted power supply back into the switch, and it is only supplying about 35mA — not nearly enough current and far below its rating.</p><p><a href="https://4.bp.blogspot.com/-MIZ_PDXfj9U/T6AJIuFal4I/AAAAAAAAAnU/RE6CdCdZnHc/s1600/theres-your-problem.jpg">https://4.bp.blogspot.com/-MIZ_PDXfj9U/T6AJIuFal4I/AAAAAAAAAnU/RE6CdCdZnHc/s1600/theres-your-problem.jpg</a></p><p>Bottom line, power supply is toast but the switch is probably just fine.</p><p>To answer the other question, it always seemed like a hardware rather than software problem. In either case, I have no idea what version of the Linux kernel it might be running. The datasheet (which the mfg tries really hard to keep anyone from getting) seems to say that the CPU is a SoC (Switch on a Chip). I doubt it’s running any form of Linux as we know it.</p><p><br></p></body></html>