Re: CP4 is definitely NOT water tight - VERY suseptible to DEW flooding


Joe Zeglinski
 

You’re welcome Elliot. Glad you enjoyed some of the tongue-in-cheeky commentary.
 
    The post came out of a lot of frustration over the past three years of using the new CP4 , but in any narrative, one can always add sugar to the vinegar.
I have always had a very high regard for Chris, and continue to value his opinion, but some conjectures can be misguided. Then again, wouldn’t surprise me if there is regular contractual or personal exchange with AP on engineering matters, for a second opinion.
 
    I will continue to trust that there wasn’t  “acidic corrosion” – being produced from infiltrated “humid” outdoor air, and certainly dew water, entering the case. Nor should there be very much dried acid,  remaining from the board manufacturing process and latent acidic manufacturing chemicals not having been washed away properly upon completion of  board assembly. Otherwise, my washing down of the milky residue with “PCB cleaner” – on the second drowned CP4 circuit board, (with Marj’s permission and guidance) – would have exposed obviously corroded fiberglass strands on the board’s substrate, leading to further damaged components. My belief is that it was mostly the result of major short circuiting from the visibly obvious  “rust” from the RJ-45,  dissolved in the water, even though “distilled  dew water” could have done almost as much.
  
To quote the great American - Ben Franklin:
“For the want of a nail the shoe was lost,
For the want of a shoe the horse was lost,
For the want of a horse the rider was lost,
For the want of a rider the battle was lost,
For the want of a battle the kingdom was lost,
And all for the want of a horseshoe-nail.”
Benjamin Franklin
    Likewise with CP4 “Waterproofing” or lack thereof, and AP’s production – for want of a toothpick-sized dab of RTV or similar rubber calk around the leak prone Ethernet RJ-45 connector ... a CP4, or two, actually so far at least four now known ... to be lost. Hopefully such laggard disregard won’t damage AP’s “competitive kingdom” in the marketplace.
 
    But really, as long as everyone has their CP4  vertically positioned, with all dew respect there shouldn’t be many more repeats of such disasters.
Of course, that excludes being struck by mild showers from open domes or direct hits from sprinklers ... on any CP4.
 
Joe
 
 
From: Steven Elliott steven447@... [ap-gto]
Sent: Tuesday, October 9, 2018 4:55 AM
To: ap-gto@...
Subject: Re: [ap-gto] CP4 is definitely NOT water tight - VERY suseptible to DEW flooding
 


Hi Joe,

 

You are a very funny man, my friend, now I truly appreciated your post, and I'm saving it! Thank You for the enjoyment.

 

Steve

 

(PS, you probably realize that vog is a legit met term nowadays? Doesn't matter if you don't know, I still LOVE your reply, it made my day)




From: ap-gto@... on behalf of 'Joseph Zeglinski' J.Zeglinski@... [ap-gto]
Sent: Tuesday, 9 October 2018 1:47 AM
To: ap-gto@...
Subject: Re: [ap-gto] CP4 is definitely NOT water tight - VERY suseptible to DEW flooding
 
 
Chris,
 
    I don’t know who at AP has been  “talking you up” on this “CP4 corrosion myth”, since I only had Marj posit that theory to me, and she not being technical, probably heard it from someone else on staff, tossing it around the table – likely, the so-called “servo engineer” who declared the first drowned CP4 was definitely not “caused by water corrosion”. Marj then countermanded his errant opinion – actually, she is way smarter than most. So, it was definitely just “plain drowning”. The high water mark, an  inch-wide white scum mark, rubs off easily, like chalk, the copper traces were unaffected, thus the PCB surface was NOT corroded. I just took it for granted that Marj uses the term “corrosion”  someone loosely, as offhand  non-technical parlance, signifying nothing other than  there was a swath,  demarcating the depth of dew built up inside the CP4 case, over a few nights of viewing time – but neither of which had bottom corner DRAIN holes, for the CP4 .... to “relieve itself”.
 
    Now, as you reported in another post’s reply below, as a professional engineer you are quite familiar with and have regularly experienced “acid rain corrosion”, such as at your observatory near the Hawaiian volcanoes. Although you attempted to apply your own circumstance to my pristine site here in Canada, you should realize that if there had actually been ANY outward sign of  “acid rain corrosion” causing the CP4’s to burn out, then the same “acidic dew” would have been raining down on my “nylon tarp”,  covering the scope over the past 6 years, (from May 2012). The nylon tarp would be a very delicate “lace cloth” by now.
 
    You remember, Chris  ---  my nylon “HINDENBURG Tarp”, as you recently referred to - covering my AP-1200, with its 900 WATT automatic dew heater underneath the tarp, keeping it at 60% relative humidity, 24/7/365, when it is not open for a few short hours during a session. Yes .... the tarp is still quite intact, didn’t burn up as you expected, doing well, with not even a single pin-prick hole in its large nylon surface – from anything like acid rain. Besides, Chris, if there were a molecule of sulphuric acid in the dew downpour entering my leaky CP4 – actually BOTH of them -  then the AP-1200 paint job would have yellowed or burned off in spots by now, as would the primary mirror coating,  my backyard lawn wouldn’t be the rich green colour it has been all summer as in every year, the beautiful flowers bloomed in my garden a few feet away, fruit trees nearby didn’t prematurely shed their leaves even until now in the fall, and there wasn’t one single dead bird in the yard – i.e. no equivalent sure-tell “Coalmine Canary”, if you please.
 
    Is that enough evidence to contradict AP’s cockamamie assumption your contact is espousing,  about “corrosion from acid rain” causing my CP4’s to fail – BOTH of them – rather than ending up as a one inch deep baptismal font? I can’t see it being your own professional, well-considered, engineering conclusion – without evidence.
 
    I assume your own CP4,  at the occasionally volcano gassed, “Waikoloa Hawaii,  is on a “new AP model” mount, rather than being attached at your site’s local Latitude angle on top of the RA axle. So I find your claim quite interesting  ... that with all the “sulphuric acid rain” occasionally hitting YOUR own  CP4, it still has not corroded (inside or outside), and yet you presume that MY far cleaner Canadian skies  have an even stronger sulphuric acid content than your VOG in Hawaii. This is Canada  ... not VENUS ! 
 
    You really should check out the pretense your friends at AP may been trying to foist on you – if that really was the case. Unlike the “vog” (volcanic fog, as you called it) near your site, the only “smell of sulphur” here on the North American  mainland, might be emanating from someone’s oval-like office, or more recently coming from under ... “a Bench” ;-)
 
Clear non-VOG skies, Chris -
Joe Z.
 
 
From: 'Christopher Erickson' christopher.k.erickson@... [ap-gto]
Sent: Sunday, October 7, 2018 7:21 PM
To: ap-gto@...
Subject: RE: [ap-gto] CP4 is definitely NOT water tight - VERY suseptible to DEW flooding
 


There aren't any corrosive gasses or particulates on the top of Mauna Kea. It is way above the inversion layer. And the humidity at 14,000' is usually around 20-30%.
 
Mauna Loa does get "gassed" by sulfur dioxide blown up from Kilauea from time to time. And when mixed with water becomes sulfuric acid.
 
My home is in Waikoloa, on the dry side of the island. Once in a great while we get a visible cloud of vog (volcanic fog) rolling through, which is corrosive. Most of the time it is the East side of the island that suffers from constant humidity, rain and corrosion.
 
Although I live in Hawaii and regularly have 60-80% humidity outside, I have NEVER had corrosion problems with my CP4's. And about every other month I am setting up my scopes within a stone's throw of the ocean.
 
 
-Christopher Erickson
Observatory engineer
Summit Kinetics
Waikoloa, HI 96738
www.summitkinetics.com
 
 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Sunday, October 7, 2018 6:05 PM
To: ap-gto@...
Subject: Re: [ap-gto] CP4 is definitely NOT water tight - VERY suseptible to DEW flooding

Hi Chris,

 

Good advice.

 

Question: Do you have any concerns about the salty corrosive atmosphere on the mountain? Trade winds blow right up the hill, eh?

 

Steve E

NZ


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