Re: strange electrical issue - anyone have any knowledge of what to do.
From our website:
25 Amp Variable Volt Power Supply (PSVPW25A)
It has a 3 prong power cord with ground plug.
From: Ron Kramer ronkramer1957@... [ap-gto]
Sent: Thu, Oct 19, 2017 3:12 pm
Subject: Re: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.
Thanks - the typical AC/DC power supplies as you are aware always seem to have only 2 prong. (no ground AC plugs)? should I shelve these cheap units and get one larger (higher quality AC-DC unit?) Powering all from it and making sure it has 3 prong AC cord?
With a volt meter - in AC mode? test the DC line out for AC?
What do you guys use for power in a AC (home) situation?
How about this? https://www.amazon.com/dp/B01MQ2PGYO/ref=sxbs_sxwds-stvp_3?pf_rd_m=ATVPDKIKX0DER&pf_rd_p=3171424582&pd_rd_wg=fneIc&pf_rd_r=9T6VWDJTX1189Y6V5DNY&pf_rd_s=desktop-sx-bottom-slot&pf_rd_t=301&pd_rd_i=B01MQ2PGYO&pd_rd_w=nshIT&pf_rd_i=Amp+Bench+Power+Supply&pd_rd_r=3582cc28-b4f9-11e7-8193-a5e4a69badd3&ie=UTF8&qid=1508436809&sr=3
I assume that both your laptop and your mount electronics are being operated with low voltage DC. That means that the power supplies are isolated from the 120 volt mains by isolation transformers. If the transformers are not faulty, then no 60 cycle current would be superimposed on the low voltage DC lines. However, I have seen many times that some of these power supplies are faulty and have substantial leakage currents that can elevate the low voltage circuits well above ground.
The mount CP4 has internal protection (transorbs) on every pin that goes in or out and is thus protected against stray leakage currents. That may not be the case for commercial laptops which are not meant to be used outdoors where you can have such leakage currents. If everything is plugged in and grounded, there may be a path to ground for these leakage currents, but unplugging the CP4 can eliminate the ground path and allow high voltage 60 cycle current to flow into your laptop input ports.
You may have to use an AC voltmeter to check your power supplies against the AC circuit ground to see if there is stray voltage on the low voltage DC side. I have heard of cases where the DC power supply had enough voltage due to a faulty power transformer that a person received a considerable shock when touching his telescope while standing on wet grass.
One other thing I would recommend is to ground all power supplies together to a common ground so that you don't have inadvertent ground currents running thru USB or other connectors.
On Wed, Oct 18, 2017 at 12:33 PM, chris1011@... [ap-gto] <ap-gto@...> wrote: