Re: strange electrical issue - anyone have any knowledge of what to do.


Roland Christen
 

From our website:
25 Amp Variable Volt Power Supply (PSVPW25A)
It has a 3 prong power cord with ground plug.

Rolando


-----Original Message-----
From: Ron Kramer ronkramer1957@... [ap-gto]
To: 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? 


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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.

Rolando

On Wed, Oct 18, 2017 at 12:33 PM, chris1011@... [ap-gto] <ap-gto@...> wrote:
 
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.

Rolando



-----Original Message-----
From: ronkramer1957@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Wed, Oct 18, 2017 9:20 am
Subject: [ap-gto] strange electrical issue - anyone have any knowledge of what to do.



I'm a proud new owner of a Mach1.  I had an issue that seems impossible.

I have a dome, and I power everything via one AC outlet on my gate near the dome.  The GF was bad on it so I replaced the receptible. The GFI "text" works... but I'm no electrician.  (could I have goofed?)

Installing the Mach1 and doing some initial testing was all good. I started playing with APCC and was working out kinks and getting SGP all set up.  With some initial problems with wifi,  I found I had to reboot the CP4 often during various configuration tweaks and the easiest way to do that was to remove and replace the 12v power plug on the CP4. 

HERES THE WEIRD PART.  Laptop was running and doing fine, when I removed the 12v from CP4 and waited, then plugged it back in - upon plugging it into the CP4 the la ptop went black as if all power was cut.
(if AC power is cut normally it will just continue via it's battery). But no...  dead. 

It didn't really hit me that plugging in the 12V cp4 power caused it... I rebooted the laptop and continued. 
a bit later I did a power off/on of the CP4 and once again the laptop went black.  This time I thought 'weird was that due to the 12v Cp4 power plug?  so I rebooted the laptop and TRIED IT AGAIN on purpose to see if that caused the laptop to die.  YES upon putting the plug in a 3rd time, laptop died and this time, would not reboot. (it's been sent in order warranty repair).  = ( 

Assuming it a fluke... bad laptop?  or maybe by using a 2 prong extension cord from the AC outlet to my setup instead of a 3 prong with ground, I swapped out the extension cord to 3 prong and ground. 

I dig out my OLD laptop to get by... and spend a full day installing software and drivers and getting it ready to take over.  thinking it may have been some sort of ground short/loop? (I dunno I'm no electrician)... I figure the ground solved the issue.  

Everything was working and I left the laptop and set up running as I left to have dinner. Upon my return, the laptop was depowered. And would not boot.  It acts like my other laptop that died, in that it powers on with just a fan and power light - but no screen and no bios or booting or error. 

MY FEAR...  I wait a month or more for my laptop to be repaired only to set it up and have this happen again.
Or worse, the CP4 dies?  Or is it the new CP4 causing this?  Not only am I out of commission until I get a nother laptop but I have nothing to do but stress over the WIERD situation? 

ideas?

The AC power goes from AC outlet to dome, to a power strip. Another power strip is plugged into one of those outlets and powers all the scope electronics.  The first power strip runs things like LED lights in the dome, fan etc.  (nothing else has had an issue).  I have a 10amp AC/DC box that runs up to a rigrunner to delegate power to focuser, heater, filters, mount cameras etc. nothing else has had an issue (yet?)

I do not suspect that powering up the Cp4 would have anything to do with the laptop via AC power... so I'm wondering.   Could it be the ethernet?  and/Or the USB connection?  Both of which were running from cp4 to the laptops.  These would be the only direct link between the Cp4 and the laptops to cause any problem.

Laptop has it's own AC/DC converter and it's own outlet on the power strip.  I am thinking it has to be related to the CP4 to laptop connection?  

Ron in MI.







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