Recently, while stowing our RVDataSat 840 satellite internet dish I thought the worst when I heard an ugly grinding sound coming from the mount on our roof. Then I noticed the controller display read “Stowing Dish” for far too long, as the noise continued. I aborted the stow and went up top to investigate since high winds were in the forecast for the evening. Sure enough, the skew motor was having a hard time. A very hard time.
I pulled up the controller interface on my iPhone and gently assisted the dish as I manually skewed it to center, then I stowed the elevation and azimuth without any further trouble, or any more ugly noises. I figured for sure the motor had gone bad. That’s what I hoped for at least, since I picked up a spare skew motor at RF Mogul after troubleshooting skew count errors a while back. After opening up the skew assembly the next day, I discovered this…
How to Fix RVDataSat 840 Skew Gear Assembly
After nearly three years of hard use – in some pretty harsh conditions at times – one of the retainer pins for a drive gear in the skew assembly had snapped. I would have snapped too, if not for the simplicity and logical design of the RVDataSat 840 antenna mount. All the skew assembly components are easily accessible, and I was able to service the the gear array, which was clearly in need of some cleaning anyway after a few seasons in the southwestern desert.
Thankfully, the pin that broke was for a gear that could be replaced without removing the reflector (dish). I asked MobilSat support for for some repair tips and a photo to have as a reference before taking things apart.
When removing the skew assembly cover, the smaller gears that are not held underneath the main larger drive gear may have a tendency to stick to the cover with grease when the cover is removed. That didn’t happen for me, but I was glad I had the photo just in case.
Note to Self: If I ever do need to replace those other gears, I will just need to remove the reflector plate by raising the elevation enough to take off the dish and unscrew the six bolts in the center.
Our system was in need of a good re-greasing. Since our motor wasn’t the problem, I had RF Mogul send me a spare pin. And since these replacements parts are so inexpensive, I ordered a complete set of spare gears and pins in preparation for the future.
After replacing the broken pin and aligning the skew gear assembly back together, I applied an ample coating of Tribolube-12 extreme pressure synthetic grease. The precise design of the 840 mount allows the skew assembly cover to align perfectly with all the gear pins and retainer bolt holes.
Finally, I replaced the skew assembly cover and added a bit of silicone sealant around the vinyl boot for the skew motor to prevent dust from reaching the gears. I then screwed the shroud back on, and a quick dish calibration resulted in smooth operation with no ugly grinding sound.
We were back in business in no time, thanks to the great support from MobilSat and RF Mogul.