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Celestron HC cable extension

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#1 hickeydp

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Posted 05 May 2013 - 07:22 AM

Just got my hands on a CGEM and I'm about to install it into my obs. I wanted to extend the HC cable and have done so using a 6 pin end-to-end connector to attach it to a regular telephone cable (for Ireland). This cable has the same size connector but only 4 pins therefore pins 1 and 6 on the hand controller are no longer connected to anything and pins 2-5 are connected correctly through the extension cable.

From the digging I have done so far, it seems that pins 1, 5 and 6 are all ground with 2, 3 and 4 being data.

Can anyone confirm this and also confirm that I will not do damage to my HC by connecting it in this way?

#2 mich_al

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Posted 05 May 2013 - 08:00 AM

I extended mine with a straght thru cable.
I went looking for a pinout but didn't find one. This site
does talk about the cable.
http://www.nexstarsi...HCExtension.htm
http://www.nexstarsi...ddsEndsCGEM.htm


If that doesn't help then this yahoo site has some knowledgeable people.
http://tech.groups.y.../CelestronCGEM/

#3 Raginar

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Posted 05 May 2013 - 08:16 AM

If you're doing imaging, I'd just use the HC for alignment and then never touch it in the end. Another option, if you are using computers, is either WIFIscope to simulate a SkyFI using WIFI or just using Sequence Generator Pro to do the same thing (and get automatic meridian flip, etc). When I had a CGEM, I wanted to do what you're talking about, but decided it wasn't really necessary.

#4 MartinTreadgold

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Posted 05 May 2013 - 09:48 AM

RJ-11 sockets and plugs have different configurations I believe, e.g. analog telecomms cable might be different to a digital modem cable... as it may be for a HC etc

Make sure you get the right sort of cable etc

#5 mclewis1

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Posted 05 May 2013 - 10:14 AM

The extension cable is an RJ11/12 6p6c (6 pin, 6 conductor) cable wired straight through. RJ12 telephone extension cables (not the 4 pin stuff) are wired as cross overs and should be avoided unless you add a 2nd crossover (from the female-female connector) putting everything back to straight through wiring.

There are a few commercial sources of cables - the best being from Scopestuff.com
http://www.scopestuff.com/ss_cgmx.htm
It's a black coiled cable that nicely matches the existing hand controller setup.

If you build your own cable be very careful of the pinouts, the electronics are TTL and not RS232 serial so the drivers can't handle being abused (wired incorrectly).

#6 neilson

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Posted 06 May 2013 - 12:27 AM

I recommend buying one that is specifically for extending the HC cable like the one from scopestuff or Astrophotography tonight. There are several different versions of the phone extension connectors that look alike. I tried one and ruined my new mount and had to send it back to Celestron for repairs. I had used a connector recommended by someone in a forum but it was the wrong one. I bought one from Astrophotography tonight this time and have had no problems with it.

neilson

#7 Fred1

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Posted 06 May 2013 - 06:22 AM

I used the ScopeStuff extension for my CGEM (when I had it, sold it with the mount) and have two others for my 2 CG5ASGT mounts (and the respective one for my Meade LX80). Been using them for a few years with no issues. At $19 they're a no brainer for me and my fairly adequate wiring skills.

#8 hickeydp

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Posted 06 May 2013 - 06:37 AM

Thanks for all the info guys. I tried the 4 pin cable and the HC seemed to work just fine however as 2 of the 3 ground connections are now disconnected, I'd be a bit worried that there is a floating ground point in the system that could mess things up. I have found a 6 pin cable that is straight through and so will use that instead.






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