MGL Avionics User Forum

I had been chasing a problem in a new V16 installation which over only a few hours flight had developed a high background noise over the intercom, and triggered even worse on tx.
After spending a few hours checking wiring, earthing, screening, and disconnecting other equipment, I came to the conclusion it was the V16 itself.

As I removed it I heard something rattling inside, opened it up and found an Al electrolytic cap (C34) had broken loose.
Its tabs had fractured at the 90 degree bend, almost certainlydue to vibration and probably not helped by the V16 being mounted inverted so any bulky components are hanging by their solder tabs.
And probably also saved by the inverted mount so the loose cap metal can didn't short out other components.

Replaced the V16, this time putting dabs of sealant on each heavy component/pcb interface to help prevent movement under vibration.
Time will tell how effective this is- better would be conformal coating over the finished assembly.

Further to this- the replacement radio has suffered the same issue.
Mounted inverted, the cap has dislodged off the pcb due to vibration.
Probably not helped in that the cap body is very close to the pcb edge and can possibly touch the lip of the mounting slot in the extrusion.
Moral of the story- don't mount the V16 inverted, minimise vibration, put a dab of silicon on the heavier caps and pcb/rail to dampen the effect of vibration.

Thanks Stuart,
we will amend the assembly and stick those things down.
It must have something to do with exactly the kind of vibration profile that V16 is exposed to - as part of the design it has undergone the prescribed DO-160F vibration tests which included vertical mounting in all 4 possible orientations. In addition I add a few low frequency high-G vibration tests in addition to that as I believe the official vibration tests are too mild for some of the smaller aircraft out there. Not everything flies as smooth as a Boeing...