I had two Futaba receivers fail at Nats due to tool dip waterproofing. One in a convoy and one in Warspite. Warspite has sunk dozens of times over the four years it had that receiver, but it finally leaked. If I had filled the case with dielectric grease, it might not have been a problem, but there was enough condensation in both cases that the boards had corroded. Thinking I could avoid the same fate in Kenya, after battle Friday I went to cut open its Liquid Electrical Tape waterproofing. Much tougher stuff, I really had to lean on the X-acto. Then I discovered I had waterproofed it without a case. So my X-acto work destroyed that receiver's circuit board. A liberal application of Corrosion-X revived Warspite's receiver, but the convoy and Kenya were now toast. I've ordered four replacements which I plan to waterproof as follows: Fill each case with dielectric grease, tape over the bind switch, then pot in free-flowing silicon so I can see what I've got inside and cut it open without ruining it if I ever need to re-bind, though I've never heard of a Futaba FAST with that problem. This is the silicon I plan to use: http://www.permatex.com/products-2/product-categories/adhesives-sealants/sealants/permatex-flowable-silicone-windshield-glass-sealer-detail I don't think I have to worry about any corrosive properties in the silicon since the case will be filed with dielectric grease. Please chime in if you think I'm wrong
Tool dip, liquid tape, and I suspect that silicone all have the same problem. Over time the coating looses it's grip on the stuff it is coating and allows moisture to seep in between the coating and the electronics it is protecting. Potting will certainly help prevent the separation to some extent but the wire antenna is still a possible point of entry if separation starts to happen. A better solution is a conformal coating such as 3M Scotchcoat. The conformal coatings are specifically made to protect electric and electronic equipment. It will not separate and pull loose over time and water dunkings.
Thanks Mike. Would you suggest leaving the receiver in the case w/ tape so it can be re-linked if necessary, or must it be applied directly to the board?
I tend to take the case off, apply it directly to the board, then put the case back on. The coating also works well for electronic switches and the boards in servos.
Another method you could use which has been in use in WWCC (and probably many other clubs) by multiple captains including myself is to remove the case and let it sit as is. After every sink or battle or even event, you simply dip the receiver in alcohol. Guys have been doing this for years without major failures.
