Servo strategy-I've killed 2 expensive servos in a month

[Lil Dylan]

First off, yes I've set my endpoints.

So I bought a $150 Savox 2290mg servo for the Noto. Super fast and strong but it started acting crazy a few weeks ago and is basically dead. If I knew how to repair it, I would. I think it might have gotten wet and that's what killed it. I sold my race buggy and transferred the Protek 170sbl to the Talion. Another $150 super nice servo. I broke that one in one day. I guess I landed off a 3ft jump wrong and broke the motor? Gears look perfect.

So, I know people ask a lot of servo questions, but I'm debating on going down the $60ish servos route and just hoping they last long enough to get me value over $150. Or should I get really nice, water-proof servos and chalk the previous failures up to bad luck? What to do.

 

[Garcbomber]

Did they burn up the board or strip gears?

Aluminum servo brace?

Is the saver locked or modified?

Within their voltage range?

 

[Lil Dylan]

Did they burn up the board or strip gears?

Aluminum servo brace?

Is the saver locked or modified?

1) All I can tell you is neither servo has broken gears. Not sure how to identify burnt boards

2) Yes, noto has all aluminum steering including servo brace. Talion has all aluminum steering except for EXB servo brace

3) Bother servo savers are adjustable and tighter than stock but not extreme.

 

[Hector_Fisher]

Logically, i'd suggest one of three issues here:

1) you got really unlucky and had two expensive lemon servos in a row. That's very unlikely.
2) your setup is causing extra strain on the servo which causes premature failure (not as likely since you say gears are intact). Unless you're overstraining the motor.
3) your ESC or BEC is faulty and killing servos.

If (3) is the case, you might just start blowing through $60 servos instead of $150 servos. I'd try swapping in another ESC if possible first. Or buy super cheap amazon servos and see how long they last.

 

[Camaroboy383]

So I think the question should be are you setting your end points? Or just running it.. it's actually pretty easy to burn out a big boy servo if your stalling the motor...

 

[GraniteFox]

I would look at the receiver or esc. Possibly something bad coming out of the bec to the servo. Hard to believe you would destroy 2 high quality servos like that. Not impossible……but highly unlikely. If you have a bench setup I would test them with different electronics.

 

[Garcbomber]

1) All I can tell you is neither servo has broken gears. Not sure how to identify burnt boards

2) Yes, noto has all aluminum steering including servo brace. Talion has all aluminum steering except for EXB servo brace

3) Bother servo savers are adjustable and tighter than stock but not extreme.

Smell them, you’ll know.

BEC voltage within their specs?
Is the servo touching the chassis, plenty of vibration/flex clearance ?

 

[dure16]

Well, you bought two non-waterproof servos in a row. That's living on the edge IMO. (unless you're going to be diligent about only running in dry conditions).

I've been super happy with the 2290. The brand new version is waterproof.

And here's a servo I don't see people talk about but it's been fantastic. Strong, fast, and durable (and waterproof). I have a few of them.

 

[ArrmaFreek2022]

First off, yes I've set my endpoints.

So I bought a $150 Savox 2290mg servo for the Noto. Super fast and strong but it started acting crazy a few weeks ago and is basically dead. If I knew how to repair it, I would. I think it might have gotten wet and that's what killed it. I sold my race buggy and transferred the Protek 170sbl to the Talion. Another $150 super nice servo. I broke that one in one day. I guess I landed off a 3ft jump wrong and broke the motor? Gears look perfect.

So, I know people ask a lot of servo questions, but I'm debating on going down the $60ish servos route and just hoping they last long enough to get me value over $150. Or should I get really nice, water-proof servos and chalk the previous failures up to bad luck? What to do.

I'm new so take this with a grain of salt....So maybe the hype about expensive servos is just that. I'd say try a cheap one or the 60.00 joint like you said, I bet you'll not regret it. Except if you plan to run on water all day. IN that case buy a boat!

 

[Surchaufeur]

When cheapass servos outlast the ones who are 3-5times more expensive... buy a local brand servo or the ds3218pro it can run up to 7.4v. Avoid the amazon coreless servos and the standard 20-25kg.

 

[Pinepig]

There is practically no way to blow a motor on a servo by shocking it in a crash or bad landing unless you physically deform the case. Gearing just doesn't work that way, you'll bust or strip a gear first ( I've done it many many times leaving a flap hanging out on a landing ). You can smoke them with high voltage ( bad BEC ) you choose the wrong voltage on your ESC or a faulty receiver, I had one smoke 2 $75 dollar servos in a few second from a short in a brand new receiver, all the other channels worked perfectly, that one channel was bad, sacrificed a $5 servo to confirm my suspicions.

Now you can overload them with long term force by having a crappy installation with, a ton of bind from poor setup or fighting against some kind of jam.

Easiest way to kill a servo is to get the internals wet, this is likely what caused your failure. Even wet grass throws a ton of water in these, as far as the servo is concerned you might as well dunk it in a bucket. Buy waterproof servos for these even if you don't plan on running them in wet conditions.

 

[Moirae]

Smell them, you’ll know.

BEC voltage within their specs?
Is the servo touching the chassis, plenty of vibration/flex clearance ?

This is what I came to post. Chassis flex killed numerous servos for me until I figured it out and added some spacers to raise the servo a bit. Haven't killed a servo since.

 

[Garcbomber]

This is what I came to post. Chassis flex killed numerous servos for me until I figured it out and added some spacers to raise the servo a bit. Haven't killed a servo since.

Yep, those tiny boards withstand enough drivetrain vibration through the 4 posts with rubber absorbers, direct to chassis won’t last long on a 6S aluminum 4x4

 

[Lil Dylan]

Thanks for all the responses. I guess, going forward I'll buy waterproof servos (didn't realize how sensitive non-waterproof servos were) and I'll be sure to lift the servo up a bit with some spacers. Neither servo is currently lifted at all.

 

[SrC]

1) All I can tell you is neither servo has broken gears. Not sure how to identify burnt boards

2) Yes, noto has all aluminum steering including servo brace. Talion has all aluminum steering except for EXB servo brace

3) Bother servo savers are adjustable and tighter than stock but not extreme.

Gear sets with BB's are available for the 2290sg. Since you are all in for the $150. , you have no choice but to get the replacement Gear Set if that is broken. Savox also sells the case if it cracks or breaks FWIW.
Have you opened it up yet??? Get used to how they work, by opening them up. I don't see how water would affect the gear train. But the Savox specs for this servo don't say it's a WP version.
I will never buy another Savox again personally. Got burned with 2 Sav. 1210's out the box were crap, Savox Warranty service sucks. Been there.
AMZ DS3235's are good enough for my Basher rigs. ( 35 kg servos) $32. I can afford to eat when they fail. Even if I get a year out them.
Have yet to break any of the 8 that I have, over 3 years later. But Servos are consumable items at some point. Can't justify $150. for just a servo when there are many out there for Less Coin. I was also a diehard Futaba Fanboy early in my RC days. They are also out of my price range now.
My 2 cents.

Edit:
I hope you setup your "ST Endpoints" properly!
A burnt IC board will usually, but not always, smell like a bastard, once you crack the case open. Invest in a cheap Servo Testor to bench test it. How I fly.

 

[Xpress..]

I'll offer some insight since I've worked in the servo industry and know a thing or 2 about servos. There is some misconception that any servo will work in any application, and that's not entirely true. You have to consider the fact that there are 3 main types of aspects in the RC world that servos are designed for and they are engineered with specific performance functions to enable them to be compatible with those 3 aspects. These 3 are:

Fixed Wing Aircraft
Helicopters
Surface (car/boat)

You have to be careful with your servo selection as sometimes when you select a servo, you may be picking a servo that is designed for a different application than what you want to run it in. Diving a little further down the rabbit hole to offer a little bit of deeper insight, servos are designed with specific performance parameters to make them compatible with their respective application. Aircraft servos are generally designed with a tight deadband to offer as precise of centering as possible as control surfaces need to have a high degree of centering in order for the aircraft to be able to track straight and true. Helicopter servos are designed with ultra tight deadbands and high refresh rates to make them ultra reactive to control input as helicopters demand the highest level of centering possible.

Surface servos, on the other hand, are not designed with tight deadbands on purpose. Surface applications are so vastly different from flying applications due to the fact that your control surface (your front tires) are in full contact with the ground and may get violently jerked back and forth during normal operation. This jackhammering effect wreaks absolute havoc on your servo, even with a servo saver, that a wider deadband is almost always mandatory to allow the servo to cope with the heavy demands being imparted upon it.

You can think of deadband as how reactive the servo is to centering its output shaft. The tighter the deadband, the more it wants to force that servo arm to the exact position its told to. This is what we want when we are in control of a flying machine- but it's absolutely horrible for servo longevity when we factor in usage in a surface application. The Savox 2290 is common in the giant scale 3D aircraft world and is held in high regard for precise centering even with very large control surfaces, but this tells me that it will make for an exceptionally poor application in surface use. Savox doesn't post their deadband specs but given the refresh rate, I'd say this is not an ideal servo for a car or truck (even if they have it listed as such on their website). My suggestion is to look into servos that are specifically designed with surface use in mind, such as Reefs RC or Perfect Pass. Even some Hitec units like the D956WP (you have to program this with the programmer to have a wider deadband, and turn some of the other functions off) work awesome for surface use.

By the way, don't go assuming that because surface servos have a wider deadband that it means your vehicle won't drive straight and true. The centering required for a car/truck is FAR less than that of an aircraft. If you've ever driven a typical sedan or SUV, and flown a real aircraft, then you'll know that the sensitivity of the steering wheel is far less than that of a yoke and a vehicle doesn't need near the amount of centering ability as an aircraft.

 

[dure16]

This is what we want when we are in control of a flying machine- but it's absolutely horrible for servo longevity when we factor in usage in a surface application. The Savox 2290 is common in the giant scale 3D aircraft world and is held in high regard for precise centering even with very large control surfaces, but this tells me that it will make for an exceptionally poor application in surface use. Savox doesn't post their deadband specs but given the refresh rate, I'd say this is not an ideal servo for a car or truck (even if they have it listed as such on their website).

Great post. Thank you for sharing.

I know this is merely anecdotal, but my Savox 2290 servos have held up to quite a bit of extreme jumping and bashing. Haven’t had one fail yet.