I have my own set of G5500 rotator woes. Mine was purchased few months ago, and just now getting around to testing on the ground. I made up 2 cables with the connectors supplied.
First attempt: UP, LEFT, RIGHT worked, but DOWN switch did nothing. After reading the schematic diagram I concluded that DOWN and LEFT voltage is on pins 4-to-6 and UP and RIGHT voltage is on pins 5-to-6. All 4 rotor control switches generate voltage between those screws on the back of the controller.
So I swapped the 2 connectors at the G5500. Problem moved from DOWN to LEFT. So I concluded there is something wrong with my connector to the Elevation rotator. I've checked voltages at the connector end with connector disconnected, checked continuity: all appear ok.
I have unscrewed and replaced the 2 connectors so many times that now both cables are displaying the identical problem: UP and RIGHT switches work; DOWN and LEFT do not.
Sometimes I can hear the inoperative motor humming, mostly no noise at all. I suspect high resistance or bad connection in the connectors pin 4, the center pin that carries the DOWN singnal to the Elevation rotator and the LEFT signal to the Azimuth rotator.
What should I try next? Re-solder the whole thing? Get new cable end connectors? Are there any connectors for this rotator of better quality than the ones delivered with it?
73, Larry W7IN, DN27