Wounded bulls
I repaired the depth sounder on my neighbours boat the other day Dick. Flavour of the month in gizmos designed to run in a battery/alternator environment is a fast semi to ground just after the fuse. The semi shorts on transients at 4 times the nominal rail voltage & pops the fuse.
Most up market avionice these days have a tamper seal so opening them to replace the 50c shunt diode voids the warranty. Nice earner for the manufacturer though, wish I had a product like that in my inventory! If warranty isn't an issue then it might be worth asking around the on airfield avoinics shops, can't hurt to have a look inside & then if you do have to buy a new one then at least you've got a repaired spare?
I remember an R44 owner's comment a decade ago when I bought my little R22. "I want you to paint a big bulls eye on your wallet", he said & that's what its been like these last ten years.
PS Tried to get a meal at Capella the other day but guest only policy. Have a word to that offspring re exemptions for old RotorHeads will ya?