Despite using 13 o-rings in our standard size servos - more than anybody else in the industry - If you're going to play submarine with them, you should consider taking additional precautions against water entry because we don't warranty servos against water damage. This is why we promote our servos as water-resistant instead of waterproof.
What precautions? Pretty simple ones, actually! The idea behind this guide is to explain techniques you may find useful to help better protect your investment against water damage. No, we're not going to void your warranty just because you opened it up to try and to protect it - but make no mistake - we recommend against operating our servos under water. Basically, you're going to learn how a tiny dab of electronics-grade silicone, plus dielectric grease, can help preclude water damage to your delicate servo electronics.
Before you begin, you'll want to have these items on hand;
- 1.5mm Allen driver
- Electronics-grade silicone sealant (GC ELECTRONICS 19-155)
- Dielectric grease (Permatex brand works well)
Note: under no circumstances use ordinary silicone, RTV, or caulk because as that cures, it releases acetic acid (smells of vinegar). The acid adversely affects metal like solder joints on the PCB (printed circuit board) as well as copper within the motor, etc. Using other than electronics-grade silicone for this job is bad juju - consider yourself warned because this is important! Anyway, with the caveat that the success - or - failure of doing this is on you because we DON'T recommend operating our servos under water, these are the steps you may wish to follow;
- Remove the four screws securing the bottom cover plate. Set them aside for later re-installation. Carefully remove the bottom cover plate being careful not to damage the o-ring. Note the orientation of the notch (at one end of the bottom cover plate). This is for the rubber boot so you'll have to align it properly upon subsequent reassembly.
- Gently lift then slide the rubber boot down the servo-wire (e.g. away from the servo) approximately 1/4-1/2" - this, to make room for applying the electronics-grade silicone.
- Using a wooden toothpick, apply a tiny bit of electronics-grade silicone (tiny as in 'less' than the size of a grain of rice). Dab it on the wire - and - work it beneath the end of the rubber boot. The idea is that when you slide the boot back into position you'll capture the silicone within the rubber boot (between the boot wall and the wire). Basically, the flexible electronics-grade silicone offers a simple way to improve the seal between the flexible wire and the rubber boot. Otherwise, due to flexing of both, gaps may form thereby allowing water an entry point between the boot and the wire. Note: ideally, there's no excess silicone outside of the boot, but if there is, wipe it off while being careful to keep it off everything other than the boot and wire. This is the reason for the emphasis regarding using a 'tiny' amount of silicone because you're only trying to seal between the wire and the boot sleeve - and nothing else - and this doesn't require much electronics-grade silicone.
- Now is the time to add a small dab of dielectric grease (for added water protection). Place a small amount - less than the size of a pea - where the wires exit the boot and attache to the PCB (printed circuit board). The purpose of this is for added protection on the off chance water nevertheless manages to work its way past the silicone you've applied between wire and boot. Belt and suspenders!
- Finally, replace the bottom cover plate plus the screws. Note; don't overtighten the screws - they're only M2 - meaning you can break them if you play at being a gorilla!
In closing, along with the factory o-rings and flexible rubber boot (for the servo-lead), you are adding both electronics-grade silicone and dielectric grease and this 'may' help preclude water gaining access to - and - damaging the delicate electronics of your servo. Yes, this seems like a lot of trouble to go through but water is bad for electronics because it may short things out and/or corrode the components. Our servos aren't designed to be operated beneath the water, but following these steps may help preclude damage if you accidentally submerge servos by, for example, running a crawler through a stream, dunking your model airplane, overturning your boat, etc. But even if you follow these steps 'perfectly' there's still no warranty, or guarantee, regarding water damage!
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John