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
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