August 26, 2017

TV Reception Rescued by using Corrosion Block®

By: Rob Lowe

Featured Picture

On a cross country trip this summer, we stopped for the night and discovered that our satellite TV Antenna was not working and that we had no TV reception. We confirmed that the receiver and TV’s were on and set correctly. We did not hear the KVH TracVision 5 InMotion Antenna going through its usual satellite seeking procedure, a characteristic of this mobile antenna. We confirmed that the antenna switch which is located in an overhead control cabinet was 'ON' and that we had suitable power. I climbed the rear ladder onto the roof and proceeded to remove the antenna’s covering dome.
Satellite Antenna with Cover Removed When my wife turned on the power while I watched the antenna components, I noticed that the Step Motor (Yellow Arrow in photo) tried to move but that was it – no further action from the antenna. The ability to rotate was confirmed so the problem was with the electronic control system.
When the antenna is fully operational there are two distinct processes the antenna goes through: First the step motor (an incremental movement motor) moves the satellite antenna reflector and LNBF ‘head’ up from the storage position in increments from laying flat to almost vertical. Then the antenna rotates the reflector and LNBF ‘head’ using it’s GPS sensor to match the location of the satellite based on the programming built into the Antenna’s onboard computer circuit board. When the antenna is operating correctly it rotates rapidly until it comes close to the position needed to pick up the satellite signal and then it fine tunes by gently moving back and forth. The step motor moves the ‘head’ up from just above the storage position and as the antenna locks on the satellite location it then steps up the head until it is at the proper angle to pick up the satellite signal. This process usually takes a couple of minutes. Since this antenna is an ‘In Motion’ version, if we leave the antenna powered while driving it will continually track the satellite by moving as the coach moves so that the signal is readily available. Our habit is not to watch TV while driving and we try to preserve the system by using the antenna only when stopped. We have found that in treed locations it is wise to allow the antenna to find the satellite while in a clearing and then while parking to have a TV on to confirm that the reception continues as we park. Sometimes moving just a few feet (or metres) makes all the difference between receiving or not receiving the signal.
I concluded that the Antenna had power to it and since the area was clear and the sky was clear there was an issue within the antenna. If the step motor does not move the head up, the rotation motor will not try to move the antenna. That knowledge led me to focus on the reason for the step motor failing to move more than a slight amount. Since the motor had power, I thought that the issue might be the corresponding multi-pin connection and the other similar connections under a circuit board. By manually moving the antenna (with the power off) I was able to access the circuit board cover (Red Arrow in photo above) enough to raise the cover to access each of the various multi pin connectors.  

Satellite Antenna circuit board
I applied Corrosion Block® to each of those connectors and then turned on the power to see if the antenna would operate.  Usually one removes and cleans the connection on each connector however the cover could not be fully removed without a lot of difficulty and disassembly. I elected to let the Corrosion Block® ‘do its thing’ and see if it operated the next day. In the close-up photo of some of the connectors you can see a few unused connector pins which are similar to those that the white connectors fit onto.
Connectors Exposed
We stopped for lunch the next day and turned on the power to the Satellite Antenna. Sure enough, we heard the usual sounds of the antenna locating the satellite and within a minute or so the signal was found and the TV displayed the desired channel.
I am writing this Blog Post two months after the failure and during this time the KVH TracVision 5 has flawlessly located the satellite each time it has been turned on. Upon reflection, I’ve applied Corrosion Block® to most connections in the RV that I could access. The antenna has not been touched since it had a recall update done to it almost seven years ago. This year the weather has been wetter than usual and the dome, while covering the antenna for protection, is not designed to be sealed to the atmosphere. Moisture in the form of water vapour can cause corrosion of the gold terminals inside the tin connectors. It took half of a day for the Corrosion Block® to penetrate the corrosion which was not visible to the naked eye, however it was able to provide the cleaning action and protection to correct the issue.
A call to KVH Tech Support revealed that the serial connector located on the power switch panel inside the RV can be connected to a computer using a serial cable. If the computer has a serial port to download a file it can be downloaded, saved and sent to them for diagnosis. If, as is often the case with newer computers, there is no serial connection, then a serial to USB adapter can be used to perform the same procedure. I’ve now acquired such an adapter so that I’m ready should I need to diagnose the Antenna’s issues in the future.  
I wonder how many serviceable dome antennas have been removed and discarded because of a poor connection after years of flawless performance? Hopefully this article will encourage you to take preventative action on your satellite antenna to eliminate corrosion and the potential for operational problems.


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