The RJ45 plug for the wire set I have plugs into the handset; that cable then splits into two separate cables with RJ22 ends for which the LX50 has no jacks of that size, except for the one labeled "handbox" which I wouldn't use in this case.
Either way, the cable ends are the wrong size for the RJ45 "encoder" jacks on the mount (fork arm and base). Would there be RJ22 to RJ45 adapters that could be used or is this too much effort to be worthwhile?
Theoretically you could do it either way -- make a completely new cable or just make an LX50 adapter cable. Either way, you are going to need someone with a Meade telescope that accepts a Magellan I to help reverse engineer what is needed. I will be happy to help with the LX50 side.
I think it will be easier to make a new cable with the RJ45 plugs on each end. The problem is going to be one of figuring out the correct pin-outs required for this new custom cable. Making a mistake with pin-outs could mean frying the Magellan I control board! The end result would be a set-up where the Magellan I plugs into the fork arm connector of the LX50 using a single cable. (The LX50 control panel encoder port would not be used. Plugging a hacked Magellan I cable in there could possibly fry your LX50 killing all normal functions of the telescope!)
You will need to find someone with a Magellan I compatible scope which has the encoders installed. You have to find out which encoder pins from each of RA and DEC go to which pins in the bottom of the Magellan I. Then you will need someone to determine how the LX50 encoder pins for RA and DEC are wired to the fork arm connector. (I can do that part.) Finally, given those two pieces of information, a new custom cable can be specified and built which will connect the Magellan I to an LX50 at the fork arm connector.
Even after doing all this, there will be a few additional details to figure out. First will be to find out whether the encoders used on the Meade dobs are the same part number and resolution as those used in the LX50. That may affect the pin-outs of the cable. Finally, any gearing and resolution differences will have to be worked out to ensure that the encoder ratios programmed into the Magellan I are correct or whether they may need to be adjusted.
All this work is part of the reverse engineering I mentioned in post #7 above. It could be done and would be a good fun group project that might end up benefiting a number of users in addition to yourself. To even get started, though, you need to find someone who can help verify the design of the Magellan I encoders and cable.
Edited by jdupton, 16 June 2016 - 06:24 PM.