Q Bill, N3SNU, asks, “The display malfunction on my ADI- 146 is definitely temperature-dependent. During summer, and to a lesser extent during spring and fall, all the segments of the LCD display activate so it is impossible to tell what frequency the radio is on, or any other displayed parameters. The radio apparently still works fine. Transmitting, especially on high power, causes heat to build up faster and the display to go haywire sooner, but in hot weather just having the radio on receive during a long drive will eventually bring on the problem. This is a mobile radio, installed in the family car, and taking it out whenever the car is parked is not a practical solution. If I had to resort to that I might as well go back to carrying a handheld and plugging it into an external antenna. Any troubleshooting suggestions?”
A This problem crops up in many LCDs in conditions of extreme heat. Typical problem conditions include the obvious (when the car has been sitting in the sun on a 90° day with the windows closed) and the not so obvious (on a moderately warm day with the radio mounted on top of the dash in direct sunlight, or mounted in the dash without ventilation space around it). The ideal mounting position is under the dash where the rig would get some shade, but adding a small 12V fan helps in installations that are less than ideal.
If the display is failing under more normal conditions, then the LCD itself or the display driver circuit is very likely defective. If the radio was purchased recently, I would suggest asking the dealer for an exchange. If the dealer can no longer exchange it, then having ADI repair it may be your only option. This is not a problem that can be easily tackled on the typical workbench.
from QST May 2000
