THE HEAT the cause
~ Captain Paul's response to: ~ Basinmaster ~
The Garmin GPSMAP 172C uses Color Super Twisted Nematic (CSTN) technology in the display screen. In CSTN Technology, the pixels in the display are actually 3 separate colored pixels. One Green one Blue and one Red. Each of those colors are controlled individually by the graphic controller chip. The CSTN pixels respond to heat and a very minute electrical current. This allows the unit to operate longer on battery power. It is a way of making a color screen display at low cost. Although the ambient air temperature was between 75° and 80, ° I bet the top of the unit was too hot to touch. The heat is what is causing the problem.
I had several black and white hand held units behave exactly as you describe when I was stopped for a while. Fortunately after covering the unit for a few minutes, the screens reappeared.
I had my wife sew a piece of elastic on the edge and the corners of a small WHITE hand towel. Basically the elastic made a circle on one edge of the towel. I then placed the elastic over the top and behind the unit. This allows me to be able to flip the towel to the rear when under way, and when stopped, flip the towel towards the front of the unit. The elastic holds the towel on the top of the unit out of the way towards the back of the unit and at the same times allows you to completely cover it when needed.
While this solved the problem, it does not solve the inheirted charasticicts of that type of screen pixel technology.
Please let me know what Garmin tells you.
~ Captain Paul ~