Buzzing Servo

[ThunderTiger]

Hi all, just upgraded to a spektrum DX3 Tx with an SR 300 Rx controlling two futaba S3305 servo's (metal geared) and i think that i may have a problem somewhere.

My problem (at least i THINK its a problem), is that even after setting the radio adjustments correctly (as far as i know), my throttle/Brake servo and my Steering servo "Buzz" (Or Humm depending which way you look at it). If i tweak the throttle trigger, or steering, it sets back to its neutral position and stops "Buzzing" for a few seconds then starts again. Is it just me being stupid or is it the servo's or radio ?? I'm a noob at these DSM radio's so i'm not sure. What i DO know, is that it never did this with my 40MHz Futaba T2PL Tx, which is why i suspect i have a Tx setting out of whack somewhere.

Could it be because i have an extra "Return" spring on the Throttle/Brake servo ? but then, thats kinda ruled out as the steering servo does the same without any extra "force" trying to bring it back to a neutral state.

When i set the radio up this is what i did

Transmitter

1) Set ALL adjustments to Zero (Thats "0")
2) Check Rx & Tx Were Bound correctly.

Throttle/Brake:

1) Removed the servo horn to allow natural neutral center point with radio on.
2) Checked servo operation with no servo horn and thus no load for correct operation.
3) Pulled throttle trigger back to full open (Tx) and refitted Servo horn with carb at a shade under fully open (app .25mm).
4) Re Checked operation of throttle action (all O.K.)
5) Set E.P.A for brake so as not straining servo.
6) Checked throttle and brake operation. All O.K, no problems, working as it should.
7) Re-Checked steps 5 & 6

Steering Servo;

1) Removed the servo horn to allow natural neutral center point with radio on.
2) Refitted servo horn with servo at natural neutral centre point and wheels set facing straight ahead.
3) Re Checked operation of steering action with wheels on the floor(all O.K.)
5) Set E.P.A for steering so as not straining servo.
6) Checked steering operation. All O.K, no problems, working as it should with no binding evident.
7) Re-Checked steps 5 & 6


Now, correct me if i did something out of the ordinary here, but removing the servo horns to re-adjust for a new radio is something i have always done. Not for the fun of it, but to ensure that both servo's have a "Natural Neutral Center point" with the ne Rx / Tx combo.

I have checked for "Metal To Metal" contact and there is none, with the exception of the mounting bolts to the aluminium servo arms, but the mounts are solidly fixed without any play or without being loose. I have tried all the trricks i know to see what is causing it bar swapping out the servo's. I Even went over my linkages, but there is still no "Metal to Metal" contact excepting the servo horns. I even tried plastic servo horns but to the same ends, the Buzzing (or humnming) is still happening.

Is there something i have missed ????

 

[ImBroken]

Here's some interesting info I just found on Towers site about this servo...

This is the Futaba S3305 High Torque, Metal Gear Servo.
per Futaba this servo is approved for use with NiCd batteries ONLY!

This servo can produce high-current draw from your batteries. If using NiMH or LiPo batteries, make sure they are capable of delivering sufficient amps.

 

[Lessen]

Here's some interesting info I just found on Towers site about this servo...

This is the Futaba S3305 High Torque, Metal Gear Servo.
per Futaba this servo is approved for use with NiCd batteries ONLY!

This servo can produce high-current draw from your batteries. If using NiMH or LiPo batteries, make sure they are capable of delivering sufficient amps.

Every Futaba servo I own has that warning on it. I don't pay it any mind. I've been using Futaba servo's for years now with great success with NiMh Rx packs.

 

[ThunderTiger]

Originally Posted by ImBroken
Here's some interesting info I just found on Towers site about this servo...

This is the Futaba S3305 High Torque, Metal Gear Servo.
per Futaba this servo is approved for use with NiCd batteries ONLY!

This servo can produce high-current draw from your batteries. If using NiMH or LiPo batteries, make sure they are capable of delivering sufficient amps.

Every Futaba servo I own has that warning on it. I don't pay it any mind. I've been using Futaba servo's for years now with great success with NiMh Rx packs.

My point entirely Lessen



Ok, but NONE of that helps me to sort out the problem i "Think" that i have, does it. Besides, i have run futaba servos and Rx units on NiMH for 4 years without problems so far, so that knackers that warning completely.

C'mon boys 'n' gals, help me out here, PLEASE. I can't run my rig until i know i'm not going to screw up my servo's, its killin me sittin starin at the thing wishing i could, wanting to, and being tempted by it, just to go and run it !!!!

 

[Cupooterluvr]

All servos will buzz at the neutral position if there is any significant force being applied to them. It's just them trying to center themselves. If there's a throttle return spring that puts constant pressure on the linkages on your car then that's probably the issue. Twitching it helps center it better so it stops buzzing. It's nothing to worry about unless it's really loud or if the servo twitches at neutral.

The 177oz 985MG and the 300 something oz 5th scale servo on my Baja both do the same thing until I twitch them and then it stops.

 

[ThunderTiger]

Could it be because i have an extra "Return" spring on the Throttle/Brake servo ?but then, thats kinda ruled out as the steering servo does the same without any extra "force" trying to bring it back to a neutral state.

Still don't make sense to me. Both servo's do it, steering servo has no "Load" on it to cause it. I can understand the throttle doing it now, but the steering servo ?? even "off the ground" it buzzes.

Thanks for the heads up though pooterluvr, guess i better get to running tomorrow. missed out some days cos of this little issue.

 

[Cupooterluvr]

If the steering is buzzing then there may be some resistance or binding in the steering linkage.

 

[ThunderTiger]

Linkage is free as a bird. Always has been. The entire buggy is Maintained and cleaned after EVERY run. Wether its 15 minutes or 5 hours, it gets a full clean down, relube (no WD40 shite) and a check for any damage or other issues. There isn't even one IOTA of rust on any part of it, nut,bolt washer etc. its that damn clean. Looks like a shelf queen, but its not. The chassis isn't even marked on the underside, excepting of course where my missus drove it into a tree and damaged the lower front edge of the kick up at the very nose. but the chassis is getting replaced anyway (2nd time around for the option chassis at £40 each).

Maybe the servo's are just dying, maybe it's me over reacting.

Either way i have decided to "Upgrade" the servo's again now i have a halfway decent radio set, a Spektrum DX3 (NOT a DX3.0).

Cheers for all the advice pooterluvr, made a mental note of it all aswell as written down certain "Check" points.

 

[Lessen]

If the steering is buzzing then there may be some resistance or binding in the steering linkage.

He's absolutely correct. I know your steering seems perfect but there IS some amount of pressure happening. Digital servos are very sensitive. It sounds to me like you don't have a problem though. If it goes away when you twitch it or pick the front wheels off the ground then it's not a big deal.

 

[olds97_lss]

The S3305's aren't digital though.

Does it do it if you disconnect the horn from the servos completely and power it up?

My guess would be that the DSM is sampling more frequently than your old radio which makes for more accurate response between you and your servos. The S3305's aren't high end servos and the pot's probably just tend to wander a bit on resistance. That combined with the higher signal/sample rate from your new radio would cause increased twitchy/humming.

I noticed similar issues on lower end servos compared to my 985MG's. When the 985's are at rest, they are fine, but just a breath of pressure on the linkage makes them hum. My cheaper JR590's, 270's, Futaba S3305's, hitec 645MG's and especially my towerpro MG995 tend to wander a bit even at rest. More noticeably like you now that I have the DX3.0 system. By wander, I mean they do what your describing, tend to hum/buzz more when the linkage is connected.

Just spit balling here.

 

[ThunderTiger]

Olds, your a diamond, you just helped me decide on what i was thinking of doing anyway.

low end ??. I paid £70 for the two instead of £40 each when i bought them, barely 2 years ago. Ahh well.

 

[olds97_lss]

Not sure what that converts to in USD, but they are $35 USD here, which is on the lower end of the spectrum. The 985's I like are $70 USD which is kind of middle of the road for price.

 

[ThunderTiger]

conversion is about 1.4USD to 1 GBP