How pleased I continue to be with my 2008 version of Losmandy G-11. After 12 years the?Gemini-1?electronics had quite working. On the recommendation several persons on different forums I entrusted the repair to Michael Herman. So I can add myself to the those who have been vary satisfied with the work he did in getting the repair accomplished. His expertise was very much in evidence. He admitted that the symptoms were very strange, puzzling to himself and the other Losmandy electronic repair specialists in the UK and Australia. But he didn't give up and expeditiously finished the job by an intelligent process - testing, replacing suspect parts. Eventually the EPROM, SRAM chips were replaced along with some smaller discrete components. He eventually tracked down the
cause of the issue.
That issue was the result of an
accident I had a couple of months ago. Let me explain. My G11/Gemini-1 had resided on a permanent pier in my garden observing site. At the conclusion of each observing session I had been covering the mount and electronics with a Telegizmo cover topped with a large plastic garbage can to provide some protection against our sometimes fierce winds here on the south Oregon coast. Since the mount usually had a significant amount of dew on it I thought it wise to place an open container of Calcium-Chloride crystals to absorb the moisture.?
So the
accident I mentioned happened when I uncovered the mount for an observing session. This caused the container of Ca-Cl solution to spill, with significant quantity of the salt solution getting on the base of the mount and the Gemini electronics chassis. I wiped off what I could and continued with the observing session. This was a mistake on my part. I should have recognized the damage this could cause and thoroughly cleaned all mount and electronics components that were covered with this corrosive solution. Yes, I didn't realize that Calcium chloride as a salt solution is corrosive to metal, that could be damaging to all sorts of parts. So the
cause of the issue Michael discovered was that some Ca-Cl had gotten into the "Hand Controller" RJ45 socket at the upper left corner of the chassis. This caused a short between some of the contacts there, leading to the bizarre symptoms that had him and the other experts puzzled.
So kudos to Michael for fixing the problem. Since he spent a number of hours over several days on the repair, his charge of $200 plus parts was most reasonable. The only part he charged for was $25 for the EPROM. Along with that came the latest version of software (Level 4, v 1.05). I wholeheartedly recommend him for any repairs to electronics that might be needed.
Moving forward from this I found the electronics works just fine. I needed to set geographic coordinates and mount limits. But everything worked as expected for two observing sessions. First night I used my little Astrotech AT115 EDT triplet APO refractor. The next night I installed my Celestron-11 with the refractor riding piggyback. This requires 53 pounds of counterweights. So no doubt the mount is maxed out. ?But these were two most enjoyable observing sessions, examining some clusters and double stars in Cassiopeia. The revelation in moving ahead came when I examined the mount in the daylight, something I seldom do. There I saw that the Ca-Cl contamination had caused some corrosion to the extreme lower end of the mount. The most affected areas were the tabs for attaching the Gemini chassis along with the azimuth adjustment mechanism. Both showed evidence of salt corrosion.
So I removed the entire mount and its adapter clear down to the cast iron flange atop the 4-inch galvanized pipe pier. Everything was cleaned with hot soapy water. There was some surface corrosion on the bronze traveling pin that moves the mount in azimuth. But I removed all corrosion and reassembled everything ?applying lubricating grease where needed. I like to use a special anti-seize compound on all stainless steel and aluminum threads. So everything is back together and functioning properly.
I'm a bit wiser in that I've learned about the dangers of employing Calcium-Chloride. In the future I will refrain from wrapping up a wet mount, and will just place the large plastic garbage container over the mount. Even if it should rain, the mount will be open to the air so dew can evaporate without needing the Ca-Cl. After the mount has dried the next day I can cover the mount with the Telegizmo cover and plastic garbage can as needed.
This brings me to a question for the forum:
To protect unused RJ45 sockets from moist night time air I am considering inserting in each such socket a spare RJ45 jack (with no wire attached). To seal each socket from the moist maritime (salty) air I am inquiring if it would be wise to apply some sort of paste that would further seal the socket. As a HAM radio operator I know of some paste that is applied to coaxial cable connections to exclude moisture. This paste is non conducting and serves to exclude water. With dew settling on the Gemini chassis there is danger of salty deposits (from marine air) on the exposed pins of the unused sockets. I have two potential pastes:
- ?Stuf Dielectric Waterproofing Filler (for coaxial connectors, with Teflon)
- Permatex Dielectric Grease (for automotive connectors like spark plugs and 12 volt lines).?
Maybe I'm trying to fix a problem that doesn't exist. The dielectric paste could be applied around the edges of the inserted plug to exclude water. Maybe there is another technique that would accomplish the same thing. Perhaps just applying some sort of waterproof tape over the RJ45 socket. I know electrical tape would work for a while. But it eventually becomes a sticky mess as it ages. Any suggestions? I'm interested in suggestions from the forum.
Best Regards,
Russ
Russell Milton