If you own old gear it will be hard to source spare parts. The contacts of the cable connecting my mount with the hand control are full of rust. Since I couldn't find any commercially available cable I put it together myself without a solder iron. The unused pins can be cut and the protrusing cables isolated with tape. Cable and connector are about US$10.
Mount: Orion Atlas EQ-G
Hand Control: SynScan V3
Cable: RJ45 (8p) to RS-232C (male)
Pin assignment:
Note that the colors of the cables inside the RS-232C connector may differ by vendor.
If for whatever reason you will have to open the front panel of your Orion Atlas EQ-G mount please have a look at the Dec connector on the print board. It has 5 pins. The Dec motor cable plug has 4 pins. Be sure to switch power off and plug it back aligned to the left (photo below). If inserted aligned to the right, the Dec motor will make a scary noise and run wild although it is not damaged. Misalignment did not cause any damage to the electronics of the author's mount, but you never can tell.