ORIGINAL: mglavin
Are you not utilizing Multiplex RX's? These have been an issue with the control signal needs of this specific series of Hitec digitals. If I recall the control voltage signal is degraded due to a resistor is series with the individual output of MPX RX's.
That problem occurred only when two servos were connected by a Y lead to one output, that dragged the data output voltage low enough to cause trouble. These are connected singly, and to 6V so there is no question of mismatching. Also, they were fine for the first bit of time and then became faulty, one about 5 minutes before the other, if there was a data voltage problem it would be there all the time. Batteries have been freshly charged, tried it on 4 cells in case they didn't like a fresh 5 cell pack, the problem is always there now.
Unfortunately this experience of Hitec servos is consistent with
every other experience I have had of Hitec servos, usually using other people's Futaba or JR radio and I have zero confidence in them now. The 5625s will be returned for repair, and then sold or binned. I expect all brands to have faulty components, I have had one crash due to an ancient JR servo going nuts, and seen a crash due to a brand new Futaba servo locking hard over on its first flight. But that is so, so, so rare. With Hitec, every handful of brand new servos that I have been asked to fit into other people's models use has contained faults. I have had them shred gearboxes while on the bench being tested with no load, I have had them run at different speeds and inconsistent travels which is very obvious on twin elevators, I have had a model crash due to one trying to turn through more than 90 degrees from centre, and so on. I know that there are people who say they have used lots of Hitec servos for years without problem, as did the people in the shop where I bought these which is why I got persuaded into buying these servos- then 50% of those very servos go faulty within 10-15 minutes.
H