ProModeler brushless servo test results

[jbeech]

I don't know if this link will work, or not, but on another forum a fellow posted some test results for some ProModeler servos he purchased from us. Nice thing about servos is unlike an opinion about how a model flies, you can mount them in a test rig and prove what you got. http://www.flyinggiants.com/forums/s...t=86935&page=1

Anyway, turns out this fellow was the giant scale columnist for Model Aviation for quite some time. Thus, unlike some anonymous 2-gallon expert (a keyboard pilot), he brings real world experience plus credibility to the table. It's a fairly short read and of interest is this information is about our 245oz-in servos, which we inadvertently sent him instead of the 520oz-in servos he'd ordered. You may find the results interesting because the 245oz-in are our top of the range brushless HV cyclic servos, which we expressly created for helicopter pilots.

[N3M0]

I have read this as well! Some very impressive servos for the price! I hope to get myself a set soon!

[boggintuff]

http://www.flyinggiants.com/forums/s...ad.php?t=90506

[N3M0]

Originally Posted by boggintuff

http://www.flyinggiants.com/forums/s...ad.php?t=90506

WOW.. that's pretty concerning. John seems like a great guy.. I do hope he makes it right.

[smwht]

Different kind of test, but I have a set of the 245-oz-in BLS servos (and the BLS tail servo) that survived this just fine... and are running strong on my new E700.

[Atomic Skull]

Originally Posted by boggintuff

http://www.flyinggiants.com/forums/s...ad.php?t=90506

Has to be something he's doing or you'd be seeing that everywhere and not just that one guy.

[N3M0]

Originally Posted by Atomic Skull

Has to be something he's doing or you'd be seeing that everywhere and not just that one guy.

I would have to agree as well.. Either that or a bad batch of control boards. That's all I could think of that would cause this kind of failure rate.

[jbeech]

The situation is unfortunate and we are sorry for this. It appears that one customer has been unlucky, very unlucky indeed. We are trying to get our arms around this so read through as we try to explain why this is such an unusual situation for us.

To begin, we assemble servos in batches of 500. We've sold 450 of the latest batch of S140 servos and until this guy, we had had 3 servos fail (from this batch). Coincidentally, only 3 servos failed from the previous batch also. In any case, in all instances we simply replaced the servos . . . no question asked. In fact, we usually ship out a replacement instead of making the customer wait until we receive his dead servo.

And note, the servos which have failed have done so for various reasons (some, upon inspection, unrelated to quality). However, when in doubt we simply replace the servo because I feel it's the right thing to do. And for proof, I offer this . . . search through the forums and find a single instance of anybody claiming I've screwed them over (and consider we've been at this since 1993). Anyway, now we add one new customer claiming 8 failures out of the 10 servos he received. This brings the total failures in this batch to 11 servos.

So how likely is this to be a quality issue when the other 439 servos in the batch are working just fine? This, versus there being an issue with the customer? We feel it's very unlikely to be related to quality, especially once we examined the servos and discovered they had all (every single one) failed due to over voltage. These servos were fried and since he claimed to have done them one at a time, it appears deliberate.

Look, we offer a servo, which is built to a high quality standard, e.g. well manufactured (and tested) but yes, some may randomly fail. However, once you realize we're talking about hundreds upon hundreds of servos out in the field, the use of statistics are helpful to understand the big picture.

Basically, the probability of one customer getting a failure is 3/500 or 0.06%. Similarly, the probability of one customer getting 8 defective servos can be computed also. This is because there are a large number of servos in each batch and we know what the failure rate has been. Thus, there are several ways to compute this probability. If for example, we use a simple binomial distribution; with probability k=8, n=450 and p=11/450 we get result of about 4e-11, i.e less than 1 in 100 billion (recall, there are 5 billion people on the planet). Yes, these are long odds indeed. Heck, the odds of one customer getting 8 defective servos are so astronomically high the customer is actually more likely to win the Powerball jackpot because odds of winning that are 1 in 175,223,510 the last time I checked.

To better understand this, imagine a set of dice with not 6-sides but 447-sides instead. Now imagine throwing that special 447-sided dice 8 times and getting same number every time. Do you begin to understand what we're taling about when we say it's so unlikely for the same customer to get 8 defective servos as to border on the bounds of credibility? Anyway, throw that 447-side dice 8 times and hit the same number and we're in the ballpark in terms of this customer receiving 8 defective servos. I'm not saying it is impossible . . . just really, really, really, really, really, really unlikely.

This means there's something else going on. For example, perhaps the customer accidentally plugged in a 3S battery pack. Yup, that would fry them. Sure, some hero-servos might even survive this for a little while - but without question - a 3S pack is going to result in an over voltage condition, which leads to fried servos. Did this happen? I dunno but he claims he fried them with a 2S and I know this ain't happening to my servos. Period!

To recap; when a single servo fails we replace it - no questions asked. However, when one customer claims 8 servos fail, we start to investigate and try to understand what is common with these servos. Thus far, the only thing in common is they all belong to the same customer! However, while we're still in the process of analyzing what happened, the unfortunate thing is we see some evidence the customer has played a little fast and loose with the truth.

For example, he claimed the servos had never been mounted. Frankly, we don't care - but upon examination - we see clear evidence of wood stuck to the bottom of some of the servos (refer to included photo). Thus, our thinking goes like this; if he fibbed about this (which doesn't even matter) then in what else might he be shading the truth? For example, he claimed his test rig delivered 8.3V but the battery he claimed to have used (a Fromeco Relion 7.2) only delivers 8.15V fresh off charge. Regardless, this is NOT sufficient to damage our servos and thus, there is something wrong with the story. What? We don't really know but he threatened to take this public, did so, and thus, he basically has painted me into a corner.

Anyway, we will be pleased to share more when we know more. Meanwhile, it is unfortunate that this customer chose to make this public because we've had to respond in kind. However, make no mistake, we are proud of the quality of our product and we're always thinking of how we can improve it. Furthermore, if you have our servos in your helicopter or airplane you now can see how very unlikely they are to fail. In fact, the way I figure it, I'm about a 1000X more likely to crash because I did something stupid than because of servo failure! The same holds for you too. Furthermore, we also know there are some pilots who are pushing our servos to their limit, but statistics show that those customer's planes and helicopters continue flying (and we want to keep it this way).

Finally, as to the question of why has this one customer experienced so many failures? Frankly, we don't know. Sure, we have some suspicions, but based on what he has 'said', we just don't see how the servos could possibly have failed. But the one thing we do know for certain is once we opened them up for a look see, we learned every single one failed due to over voltage. Meanwhile, we stand by what we told him - we will be pleased to repair them but not for free, e.g. not under warranty because it is quite clear to us this is not a failure due to our fault.

Basically, we don't feel his claim passes the sniff test . . . but draw your own conclusions.

[kpod]

Ive got the 140's on cyclic and 110 on tail of my 6hvu and they have been working great using a 2s rx pack. John, ive got my logo 480 now and cant wait to get some promodeler mini hv servos for it. Any idea when they are coming out?

[quinn]

not sure if you figured your whole equation of this or not, but 3 out of 500 is .6%, not .06%. however still a very slim chance for 8 out of 10. another thing to think about is the fact that it only takes one bad servo to take down a heli so if people buy them in sets of 3, 1 out of 166 chance (3 out of 500) of a particular servo going bad turns into a 1 out of 55 (2%) chance that one of your 3 servos will fail and take down your whole heli. still pretty slim odds, just thought i would point that out

[distructor]

I've got 4 ProModeler on my 800 running off 2S 3600ma Pulse batteries with over 100 flights. I always a start flying section with a fully charged Rx pack. Servos have been flawless and have another set on the way for my 700 build. I'll take John's word as fact.

Sent from my SAMSUNG-SGH-I317 using Tapatalk 2

[Dr. M]

This sort of thing always turns ugly when it's aired in public...

I for one am happy with the PM servos in my Goblin Speed (flying for 6 months now), and have always received superlative customer service from JB.

[bakerch1]

I have yet to have the opportunity to buy a set of these servos, however I have had the honor of dealing with Mr. John Beech on other products he offers.

Let me first start out with the fact that Mr. Beech is the owner and operator of his company in which he takes full pride and commitment in which truly shows by his customer service practices. My experience was nothing short of exceptional due to the fact that Mr. Beech replied back to my emails promptly, thoroughly, and even on a Sunday! When I started my communications with Mr. Beech I had no idea that he was the owner at the time. Also to find out during our communications Mr. Beech was on Vacation and still taking the time to reply back too my needs.

I would like everyone that reads this to take a moment and think about how many times during your hobby purchases have you ever had the exceptional service of talking with the owner, to the individual that has all the information at hand with out redirecting you to a customer care tech. Mr. Beech's commitment to his customers speaks volumes of his dedicated service and products.

I without a doubt will install PM servos in my heli when I bite the bullet and set it up as an HV setup..

[metallica944]

I am sad to see this, I couldn't be happier with the PM servos in my 700.

[Atomic Skull]

Originally Posted by bakerch1

I without a doubt will install PM servos in my heli when I bite the bullet and set it up as an HV setup..

I wish he'd get the coreless back in stock it's holding up completion of my X600.

[Jermo]

Tested mine and they work just fine.. *shrug*