@Paul Lytle posted:... I found that changing the radio pickups seems to help. if you have an old failed board you can remove from old board and install in the board your having issues with. I was able to swap out while board is still in the engine by installing a wedge between both board which held the bottom board up so i could unsolder and remove the frequency filter and replace with others.
I am impressed that you discovered this "failure mode."
The two items you circled are crystals. And if I understand what you're saying this could be a temperature phenomenon since the frequency of a crystal oscillator drifts with temperature in a somewhat defined/predictable manner. We're talking in the parts-per-million category but it's a temperature dependency nonetheless. That's why it might work for a while until the circuit board warms up and the frequency of the crystal drifts enough to cause a problem. In fact, if you run across another board set that behaves as your describe, then take a can of compressed air, or can of component cooler, and give a blast right to the crystal. If all of a sudden you restore DCS communications, then you know you're on to something.
