Another of those "did a lot of work, made little observable forward progress" updates…
When I started my panel design, Garmin made two audio panels, the GMA 340 and the GMA 347. These had different capabilities – the 340 is all analog and the 347 features digital processing – as well as completely different mounting trays and connector pinouts. I went with the 347 on the basis that it must have 7 more "somethings" than the 340.
Fast forward to now… in the intervening years, they've come out with the GMA 240, an excellent low-cost audio panel targeted at us homebuilders, and the GMA 350, a high-end all-digital number. Both of these new audio panels use the same wiring as the old GMA 340, which makes my 347 sort of an odd man out. Given that the 240/340/350 pinout seems to be the favored arrangement for audio panel connectors these days, as well as the fact that the GMA 240 is also lighter and cheaper than the 347, I decided to remove my existing audio panel and convert to a GMA 240 tray. Might as well do it now while I've still got access to the wiring, as it would be almost impossible to do later.
Old audio panel tray removed:
Redoing wiring in accordance with the new schematic I drew. Fortunately it was mostly a matter of de-pinning wires from the old connectors and re-pinning them in the new ones, with only a few new wires or splices required.
Connectors tested, strain-relieved, and sealed up:
I enlisted Mary's help to reinstall the tray in the radio stack, as there was one stubborn fastener which was impossible for me to reach from both sides simultaneously.
New audio panel tray bolted in place with connectors installed. I'm glad I did this now, because the only way to access these connectors once the top skin is riveted on will be with a crash axe or a stick of dynamite. Maybe both.
Testing… everything works!
So I spent a bunch of hours removing a perfectly good audio panel and replacing it with another one. But at least the new one is lighter by a pound and a half, and its seemingly more common pin arrangement might save me some trouble down the road.