servo buzzing

[eight_balljake]

i am new to this hobby and just finished putting a Great plains "Spirit".On testing my controll functions i noticed one of the servos buzzes wene everything is on.it does rest against the side of the fuse.but only does it once and awhile and continues to buzz wene sticks are in the neutrel position.its a brand new servo.could it be that because its on the fuse that its noticable?Or is this a bad thing????????in a hurry to try this out but not THAT much of a hurry........any help??:confused:

[Vito]

I have had this happen as well and have always felt that it was due to the linkage hanging up and not letting the servo return to real neutral. I usually try to bend the wire or control tubes to make them move smoother. It is easier if I disconnect the linkage from the servo and feel for spots that stick. I must admit that I am not always successfull and have an OV-10 that I never finished building because I couldn't get it to stop buzzing. Maybe someone can tell us if I am all wet or maybe something that I have not tried.

[eight_balljake]

Thanx !I tried unhooking the linkage but they still "buzz".I even Swithched with my other two(spare) servos...........they buzz too.they buzz in plane,outa plane,on the sofa an on the table.......BUZZ BUZZ BUZZ:eek: :confused: :mad:

[beefa]

Hey Jake,

I finished building my Spirit last week : ) and flew it for the first time yesterday, sloped it in stiff winds that was blowing thermals up the slope every 5 mins which would let me jump the plane up a couple hundred feet, then run it out and back into the slope lift... awsome.

As for your servo's.. have you tried each servo at a time and in different channels, I had a problem building mine, where i was using 2 GWS servos for Rudd. Elev. and a HS-80 micro for the spoilers. This combo would cause the HS80 to glitch and spasm. Ended up using two HS80 micros, and 1 GWS for spoilers and it fixed problem.

Also make sure your not in a "noisy" environment, and that the antenna of your TX is screwed in all the way and its turned on.

Things i have found that effect the signal are PC's (although i think its the monitor) infrared devices, and other high voltage devices.

Regs,
Beefa

[Konrad]

Hi
The servo jittering you notice with no linkage attached is coming from noise on your servo leads. Modern servos have very high input impedance to the servo amplifier. High input impedance is a desired trait of an amplifier circuit. This is so the first stage (input) does not distort the incoming signal. Cheap Low-grade servos have the gain set to high to try to mask the large dead band. This along with poor input filters and voltage regulation will make the servo jitter. I think most people mistake this jitter for buzz. The classic buzz of a stalled servo is hard to mistake. Test out your servos by butting an arm on the output and listen to the sound of the servo when you gently try to twist the output arm. Twisting the output arm is what a stalled servo sounds like. The little jitter at neutral with no load is just the price of a cheep servo. This is not to say that you could not have a set of servos with binding gears or some other failure. But if you can hear a distingue difference between the idle and stall test you are probably OK. The real test would be to use an amp meter. In rough numbers the RX should draw 50milliamps and each servo should draw 20 milliamps of current.

A fix for the jitters is to twist the leads. This is why the servos from the good old days were twisted. The ribbon wire (lead) used in automation of the servo assembly line is very poor at suppressing these noise transients on the lead.

To make a twisted lead I remove the pins from the connector (note how they went in). Then I pull the three wires apart. I twist (some times braid) the three wires together. I use a heat gun to set the wires so they don’t un-wind. Plug the wires back into the connector as noted.

Consider buying quality next time. All manufactures have an entry level of product. This should not color your opinion of the brand you may have. No $12US servo is going to match a $189US servo! That being said I like the Multiplex mc/2v family of servos,
Konrad

[onlyfingers]

Now and then, on my own and with help, I plant my MAD Highlander in the ground, nose first. Apparently, the flex of the fuse against the control rods which do not flex strips teeth from my servo gears. Several months ago, a servo began turning free--the servo was working, AFIK, 'cause I could hear it. But the rudder was not moving. A stripped servo, I assumed, so I got a exact replacement, took the covering and tape off the fuse, and replaced the servo. (The plus is that I got to tighten up the plane, which wiggled like a loose tooth around the CG after bouncing on the ground a few hundred times.)

After taking a dive the other day, the elevator "sticks" or jerks at a given point in its travel. I assume that another servo is on the way out. So soon I am going to replace another servo. I would like to hear from a veteran or two about whether I should get a metal servo or get servo savers or learn to replace the stripped gears. The sevos I have in the plane are HiTecs (don't remember the model, off hand) that I salvaged from a Thunder Tiger Windstar EP ARF. The one I replaced cost about $15.

[RRD]

Originally posted by onlyfingers
Now and then, on my own and with help, I plant my MAD Highlander in the ground, nose first. Apparently, the flex of the fuse against the control rods which do not flex strips teeth from my servo gears. Several months ago, a servo began turning free--the servo was working, AFIK, 'cause I could hear it. But the rudder was not moving. A stripped servo, I assumed, so I got a exact replacement, took the covering and tape off the fuse, and replaced the servo. (The plus is that I got to tighten up the plane, which wiggled like a loose tooth around the CG after bouncing on the ground a few hundred times.)

After taking a dive the other day, the elevator "sticks" or jerks at a given point in its travel. I assume that another servo is on the way out. So soon I am going to replace another servo. I would like to hear from a veteran or two about whether I should get a metal servo or get servo savers or learn to replace the stripped gears. The sevos I have in the plane are HiTecs (don't remember the model, off hand) that I salvaged from a Thunder Tiger Windstar EP ARF. The one I replaced cost about $15.

I had the same problem with my Highlander. Definitely get some servo savers. Stiffening up the tailboom with a carbon rod or extra strapping tape doesn't hurt either. It's a great glider, but the flexy tailboom is hard on servos and makes the glider a lot less responsive.

Heres a link to a great Highlander How-To. There are other links at the bottom of the page.

Charles River Highlander page (http://www.charlesriverrc.org/articles/kitmods/williamson_highlanderhowto.htm#Tailflex)

Bob

[Jack Hyde]

Learn to replace gears. It looks a lot more difficult than it is. I have used plastic and metal gears. For everyday use in a Highlander, I would go with nylon gears and keep a few sets of extra gears on hand, $3 per. Figure on replacing gears once in a while.

[eight_balljake]

konrad.you win! Thanks so much!i did as you said and twisted servo leads..used heat shrink tubing to keep'em twisted and they quiet as a sleepin baby:D
servos are jr ner-600s are these considerd "cheap?"they came with the radio,a jr xf421ex.well i beleive all is well.....wind about 15 mph.........little more than i wanted for my first flight of my life.but i think i'm goin anyway.Like I have said earlyer,no one here that flys that I have found yet so it's all of your clubs great advice and help with a hope a prayer and sum nervouse guts to a large open field I'll let ya all know what happens...........thaks all again .what an awsum site.Its like havein a r/c club in my living room!