servo got weak?

[zkid009]

had a little bit of a wtf moment this evening and wondering what you guys thought about it...
im running a losi night crawler, MG 946r servo, stock esc, 2s lipo.
i havent been able to crawl much other than around the yard since i got the servo. today i went down by a creek close to my house and it seemed to do alright, got home and i was attempting to crawl up my stairs and the servo seems super weak...
now, last night i wired my BEC straight to the servo because it seemed like the servo always seemed weak. i read alot of people doing this and i figured it might give it a little kick in the butt.

it seems like its running out of umph around 7.7 volts or so according to my battery charger/balancer. i plugged it up thinking maybe the battery was getting weak but that was a negative.

i did notice it seems like the servo has a fair amount of play in it... i can move the wheels 1/2- 2/3 of an inch or so while its sitting still.. it is also getting hot. seems like the servo is getting nearly as hot as my esc

could the servo be about shot, or is there an issue somewhere else?
has me stumped as to why it could be like this without much time on it

[Charlie-III]

I would disconnect the servo from the steering, then move the steering full travel to see if there is a bind. That may be your issue.

Also check the steering EPA's, if you are binding the servo at full turn, it can heat it up. That WILL kill it quickly.

[AR Fabrication]

Is the play slop in the linkage or is the servo arm moving also?

[zkid009]

The servo arm is moving also.
My EPA could have been off. I thought of this last night and adjusted them a little. They didn't seem WAY off though.

Another addition just to see if it could contribute.... I made a plate for the front to mount my servo and esc. I put the servo on the passenger side of truck so I could use a super short drag link. My drag link uses revo ends and has about 1/4" between the ends from being butted together. Those put more of an angle on the drag link, but have seen a few people doing this. Could the angle of the drag link harm anything??
Can get pics if needed

[AR Fabrication]

Pictures would help. It's possible that a short drag link and a chassis mounted servo changed the geometry and reduced the amount of throw. As for play in the servo, I would open it and inspect the gears and bearings.

[zkid009]

Okay I have an update.
I bought two servos at the same time. Same servo though.

I swapped back to the stock servo plate and made drag link so it's in line with the servo. No angle in it at all. I soldered the bec to the positive and negative wires on the servo, hooked the signal to the receiver, and this servo is just as weak as the other. This servo has no play of course, but when the crawler is sitting on carpet, it won't even turn the wheels all the way either way.

End points are good and I don't have any other ideas.
Could it be a BEC going bad orrrr what should my next step be ?

This mess is killing me. I was going to order a new servo but after trying this new one, im not 100% it is the servo.

Help me out before i pull my hair out haha

[JohnRobHolmes]

If the servo is getting hot, like above 140f on the case, the motor is stalling out and overheating which causes power loss. Once that happens its a downhill slope.

[DioptricStraw]

I was having the same sort of issue with my 7950 a while back. After changing out the older Castle BEC to one of the newer ones it was like night and day, try a new BEC.

[zkid009]

I think I'm going to go back and wire the servo straight to the reciever and see if maybe the bec is going bad or something.. If there's any improvement, wire the bec straight to reciever and see what the result is...

I'm using an off brand BEC that my lhs sold me. Maybe it's about seen its better days??

If anybody else has ideas or has witnessed this, feel free to chime in and help out!

[zkid009]

Okay guys, failure.
I cut the bec out, wired it back to the plug and ran the servo right off the receiver and it was even worse.

Here's a video. If it doesn't work, tell me and I'll try another link





http://i236.photobucket.com/albums/f...9/40f3d1a8.mp4

[Bgreene]

How many volts is it bec putting out? I had this same problem and then found out my bec was only set at 5.1 volts.

[SMR 510RR]

I have been having similar issues with one of my servos, common between our setups is the GT3B. I believe that my RX is going out and causing issues, if you have another RX to try I would give that a go.

I plugged that servo into one of my Spektrum setups and it works just fine.

[zkid009]

i thought about that as well!
however, having the BEC wired directly to the servo, only the signal wire would be going to the receiver so the receiver wouldnt actually power it.
i actually ended up putting the stock LNC servo in it and its heaps stronger than the other two. why? i have no idea.
i then wired the BEC straight to the stock servo and it was stronger than off the rx so im assuming i just have two junker servos.... i cant think of anything else :\

[zkid009]

And sorry I forgot to answer about the bec volts.

I'm not sure how many volts honestly. It's an off brand bec but i tried hooking it up to my castle link with no success.