Erratic Servo Question

ZW99GT

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Arrma RC's
Senton
HI Guys,

I just picked up a cluster of bolts of a project, which eventually will be known as a Mugen MBX6 ECO. I'm looking to swap whatever I like into the Senton, once I get this all straightened out. Everything looks to be complete and half working, but ANCIENT, aside from the motor/ESC, that's fairly recent. TrackStar 1900kv and XErun SCT PRO

Hoping some of you guys can help me out real quick. When I power the car on, the servo (JR Racing Z650M) works great. I have endpoints set great, dual rate set just where I want it. With weight on the wheels, it turns them effortlessly. Trouble is, after a quick forward pull, the servo acts very erratically. The trim is all out of whack (right and left and all over the place) and I have 10% steering, if that. The servo sounds like it's moving fine, but it will not move the arm at all. Bolt in arm is tight. Turn the car off and then back on, it's perfect again. Very strong, complete throw of the servo.

Any ideas?


I've been reading up on using capacitors to hopefully help with issues like this, but I don't understand how this setup on the battery wire would help. I plugged it into the battery port in the receiver, but it keeps the ESC on all the time, and made no difference

CAPS.jpg

RECV.jpg
 

Dreadstar

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Fury
It sounds like the servo requires more power than the esc's BEC can provide. You may well need to get a separate 7.2V bec to run the servo,go to RC Adventures youtube channel for a video showing how to set one up.
 

Dustin Mustangs

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Granite
What kind of battery are you hooking this up to? That servo is only rated for 6v so be careful, 2s or more might let the smoke out. Same concern for that reciever. And certainly don't hook it straight to your battery and your esc bec at the same time.

Try hooking that servo up to your senton and see what happens. Same for the esc, connect it to your senton's servo and test it. I would suspect something is faulty because the bec in that hobbywing puts out 3a which should be plenty.
 

OrangeDRAGON

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Arrma RC's
Fury, Raider,
Yeah I'm not digging that battery-to-servo-side power thingy... The BEC in the ESC is designed to control voltage and can provide up to 3a of current as @Dustin Mustangs said. It looks like someone tried to provide full battery voltage/current on the servo-side to overcome a weak BEC (or to not have a BEC at all).

I have (and use) a cap pack (also called glitch buster) on the servo-side of the Rx which helps smooth out current/voltage drops - but that is just a capacitor (or bank of them) directly plugged into Ch3 of the Rx and is fundamentally different then trying to run power directly to the servo-side of the Rx which is already powered by a BEC. When I power off my ESC there is definitely no power going to the servo.
 

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