Hitec 7954SH glitching at 4.8v

[ik632]

I have my new 7954sh that showed up yesterday and plugged it into my test receiver setup. I ran it with a 4-AA pack using Alkaline so it's about 6v and the servo is very glitchy. I also tried it on another receiver powered by ESC BEC (Sidewinder SCT so it's 4.8-5) and it's also glitching.

Does that receiver need the full 7.4v from a 2S LiPo to not glitch?

[Charlie-III]

Describe it better, is the servo arm moving around a lot, or is it still but making a buzzing sound?
Quite a few servos will make noise when "resting", digitals seem to make more as the servo "hunts" for a steady spot but this is normal.

Your voltage should be fine.

[ik632]

I can take a video when I get home, but I'll try to describe a little better. Basically when it's sitting centered it's buzzing. Then when you turn the wheel (channel 1 for steering) it moves to where it needs to be and then let go and it centers. When it centers it buzzes and wanders back and forth a little before centering.

[Trubble]

Is you test receiver an old AM radio?

[indiana mudcat]

It's pretty common, AM radio systems will be worse. I freaked out the first time I bought a digital servo because of the noise also. More voltage does slightly help as it gives the servo more power to help find center when traction is high. I.e. it'll be louder on carpet than hardwood as the wheels turn easier on hardwood, same with voltage but to a lesser amount.

[Charlie-III]

Originally Posted by ik632

I can take a video when I get home, but I'll try to describe a little better. Basically when it's sitting centered it's buzzing. Then when you turn the wheel (channel 1 for steering) it moves to where it needs to be and then let go and it centers. When it centers it buzzes and wanders back and forth a little before centering.

Sounds pretty normal, as stated, AM/FM radios may add a bit to the "centering buzz" but you'll still get the same thing with a 2.4ghz radio.

[ik632]

I have a FS-GT3B which I plan to use in the crawler (which I've been testing with) but also tried it with a Traxxas 2.4ghz system too. Both systems are 2.4ghz.

Might be that I've been using analog servos all my life and I'm just worried over nothing.

[ik632]

Here's a video of the worst "glitching" that I saw. It was when running some batteries which have mostly been used for testing like this.

[ik632]

Servo connected to receiver powered by Sidewinder in my MERV.

[ik632]

Final video of the receiver and esc I plan to use in the truck. The servo will run direct off my 2S LiPo so it should have as much juice as it wants. In this one it's connected and run from ESC BEC. Noisy, but looks like it's running better. I'm wondering if the AA's I have in the receiver pack just don't have enough juice.

[littletoyboy]

I bought the exact same servo last weak. it has the buzz, butt no glitch. running off 7.2v and 2.4ghz radio.

[ik632]

it's a little hard to hear the buzz in the video but I'm happy that everyone else has the buzz. I'm really beginning to think that the 4 AA's just don't have the juice and that's why it was glitching so bad in the first video. It was solid with the BEC's running it.

Thanks again for the help guys.

[Charlie-III]

Originally Posted by ik632

it's a little hard to hear the buzz in the video but I'm happy that everyone else has the buzz. I'm really beginning to think that the 4 AA's just don't have the juice and that's why it was glitching so bad in the first video. It was solid with the BEC's running it.

Thanks again for the help guys.

The qty-4 AA's, between the carrier, small wires, low mah likely have issues with the amp draw of a digital servo. This is why it's better with the BEC.
Did you use the same radio for both tests? You may have a dirty/worn steering pot in the TX which adds to the glitching which is emphasized by the fact the servo is digital. Also having no load on the servo does not do any damping of it's movement.

I vote it's fine, just run it.

[ik632]

Thanks Charlie, I think this makes all my suspicions better.

The funny part is when I was recording the videos out in the garage then uploading them my wife was all interested to see what I was working on. Then when she watched the videos she told me I was a dork. Haha