[TenTec] Orion 565 failure due to electromigration of solder

[A R]

Just recovered from a failure of my Orion 565 that looks to be a result of ionic solder migration.

Orion was purchased two years ago from original owner's estate. Details of his operation/use are unknown.

Replaced snaphat battery, A9 caps, and intermittent VFO encoder. Orion performed flawlessly for over a year following those measures, and was relegated to back-up status about 3 months ago.

When it was brought back into service, receiver worked fine, but no transmitter output on either ANT 1 or ANT 2 outputs. Two master resets were performed, but no joy. Covers were removed, and interior subjected to the burnt component "smell test", and visually inspected for any obvious causes (loose cable connectors, etc.). Discovered powdery substance on the I/O board that surrounded the entire periphery of TXEN 1 rca jack solder pad (perfectly circular around solder pad) intersecting the adjacent +13vdc wire conductor solder pad, with a "track" extending to ground side (anode) solder pad of adjacent 5KP15A surge suppressing diode. Removed the powdery deposit using Q-tips and 90% isopropyl, followed by judicial flushing with distilled water.Gently and slowly dried with warm (not hot) air, and after 10 minutes of ambient air dry time, applied power. All sytems are "go", and the Orion lives again.

I have never used the TXEN or TXOUT jacks, but don't know whether the original owner did. At any rate, the condition (which I attribute to electromigration of the solder) had to have resulted/propagated with no externally applied potential to the TXEN jacks, since the condition only became "fatal" after two years of problem-free operation/life. The internally applied potential to the TXEN pad/lead is just +3.3vdc. And, the distance from the TXEN's pad edge to the diode's anode (ground) pad edge is more than 1/2 inch, and distance from the +13vdc pad edge is approx 3/16 inch. Since the deposit was uniformly centered around the TXEN's pad (and, not the +13vdc pad edge), it would seem that the donor was the TXEN pad/solder.

Given the wide spacing between these pads/solder and the low potentials involved in this case, the potential (no pun intended) for similar failure conditions elsewhere (with closer pad separation) would seem quite possible. So...I guess my counsel is to do a close visual inspection (under magnification) of boards when unexplain/unprovoked failures occur. Or, maybe better...periodic visual board inspections...or, even cleaning...BEFORE electromigration causes a failure. Fortunately, in this case, the condition didn't result in permanent (and catastrophic) damage. An ounce of prevention....etc.

73,
Allen--W7GIF