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Help with broken servos. Please!!!!

cdfigueredo

Well-known member
#1
Recently a friend received a package of servos as a gift from abroad. It is a package like this one. The problem is that several of the servos don't work. When you connect them to the servo tester, they don't even react. :cry:

Is there any way to try to make them work? Could it be a loose wire? Any ideas? Getting servos here is very difficult, we need help repairing them. :rolleyes:
 

BS projects inc.

Well-known member
#2
Those servos are known for not being of the highest quality. I use them all the time but they are kinda burner servos, and are popular for scratch builds. Here is what you can do. Check them with something other than the servo tester you are currently using, make sure that the pins in the connector are not loose, and after that you can open up the servo and check if the wires are lose. After that you can pretty much conclude that they are bad.Good luck with this.
 

quorneng

Well-known member
#3
It may sound obvious but are you sure you lugged them into the tester the right way round?
You are running the servo tester on a 5V regulated supply?
These cheap servos don't like anything above 6V.
If your tester has more than one output plug then plug in one good and one bad at the same time. If the good servo still works then clearly there really is something wrong with the bad one.
If more than one servo has failed a bad plug connection (possible on the servo tester itself) is more likely than several servos failing internally.
 

cdfigueredo

Well-known member
#4
Those servos are known for not being of the highest quality. I use them all the time but they are kinda burner servos, and are popular for scratch builds. Here is what you can do. Check them with something other than the servo tester you are currently using, make sure that the pins in the connector are not loose, and after that you can open up the servo and check if the wires are lose. After that you can pretty much conclude that they are bad.Good luck with this.
Well, that was fast!!!
I will do that, will ask to my friend for the broken servos and will try to chek those. I will usw TX/RX to test them, but my servo tester is ok, i use it all the time with no issues.
Thanks for your advice.
 

cdfigueredo

Well-known member
#5
It may sound obvious but are you sure you lugged them into the tester the right way round?
You are running the servo tester on a 5V regulated supply?
These cheap servos don't like anything above 6V.
If your tester has more than one output plug then plug in one good and one bad at the same time. If the good servo still works then clearly there really is something wrong with the bad one.
If more than one servo has failed a bad plug connection (possible on the servo tester itself) is more likely than several servos failing internally.
As obvious as it sounds, it's still a valid cause. Sometimes we miss things. But that's not the case.
My servo test is fine, I use it all the time even with cheap servos. Seems like those servos aren't really good. Or it's just bad luck. :(
 

sprzout

Knower of useless information
Mentor
#6
Odds are, the bad servos aren't going to work. People buy large quantities of these things on the assumption that a few of them were poorly constructed, and quality control is either very poor or non-existent. Sometimes it's worth paying a little more for better quality servos. Think about it - if a bunch of them are failing on the bench before you put them into a plane, how long are they going to work before potentially failing in midair?
 

cdfigueredo

Well-known member
#7
[QUOTE = "sprzout, post: 535096, member: 34177"] Las probabilidades son que los servos malos no van a funcionar. La gente compra grandes cantidades de estas cosas bajo el supuesto de que algunas de ellas estaban mal construidas, y el control de calidad es muy pobre o inexistente. A veces vale la pena pagar un poco más por servos de mejor calidad. Piénselo: si muchos de ellos están fallando en el banco antes de ponerlos en un avión, ¿cuánto tiempo van a funcionar antes de que potencialmente puedan fallar en el aire? [/ QUOTE]

You are right!!! Unfortunately we can't buy parts from here where I live and we have to make do with what we have. I'll try to see if they have any visible defects, something like a loose wire or bad welding. If not, we will use them to make some good extensions or Y-harnes. ;): LOL:
 

BATTLEAXE

Well-known member
#8
I bought a package very similar to what you have linked and it took forever to come in the mail, over 6 weeks. I have used 6 out of the 10 so far and I did notice the new ones are not the same compared to the other TowerPro SG90's I have sourced from elsewhere at over double the price. I thought I was getting a deal on the same servos but I am skeptical of their performance. They are definitely quieter, which being different then what I am used to was a red flag, and they seem to be slower to, especially at the end of the throw. It seems they move fine at the first 60% of either direction but the last 40% it seems there is a slow delay in action to get to the end. I have them in two planes now but haven't flown them yet.

I was the same as the rest thinking that maybe its the tester but any other servo I tried with it acts normally, buyer beware I guess. You never know what you are going to get when it comes from China
 

sprzout

Knower of useless information
Mentor
#9
I bought a package very similar to what you have linked and it took forever to come in the mail, over 6 weeks. I have used 6 out of the 10 so far and I did notice the new ones are not the same compared to the other TowerPro SG90's I have sourced from elsewhere at over double the price. I thought I was getting a deal on the same servos but I am skeptical of their performance. They are definitely quieter, which being different then what I am used to was a red flag, and they seem to be slower to, especially at the end of the throw. It seems they move fine at the first 60% of either direction but the last 40% it seems there is a slow delay in action to get to the end. I have them in two planes now but haven't flown them yet.

I was the same as the rest thinking that maybe its the tester but any other servo I tried with it acts normally, buyer beware I guess. You never know what you are going to get when it comes from China
Yep, I'm experiencing the same thing. I bought some similar to what was listed in the first post, and I have them in a Baby Blender. When setting up the throws last night, I noticed I'm not getting full travel on one end vs. the other. I thought it might be the beveling on my elevator, but that's not the case at all - there's actually a bit more movement it could go when looking at the theoretical travel area. It's not a problem, because it travels more than what the high rates should be set at, but it still concerns me on quality of the servo. I'll fly it, but I'm not going to trust that it's going to be a long term servo like my Emax or Hitec servos.
 

BATTLEAXE

Well-known member
#10
Once I get into balsa I will be using higher end servos for sure, I am not gonna let technical issues take out a balsa build that's for sure