ruffrider28435

I just noticed that my savage xl has radio glitches. I changed the crystals out it was ok for a while i came back out later that day and played with it it started doing it again today. sometimes it does good sometimes it starts messing up. I had the truck now for two weeks is this a common problem with am radios and how can i fix the problem?

BudBud

It is fairly common, especially if the radio antenna is really close to the rx. Also I have a couple that leap anytime I touch the truck with a screwdriver to adjust the needles. Nothing like trying to adjust the needles when the truck wants to jump three feet as soon as you touch the carburetor with a screw driver.

ruffrider28435

Is there a fix for this? Are do i need to switch from am to a fm radio? If i was to switch to a fm radio do i need to change my servos are will they be fine?

3-172IN MTN

depends on your servos and if it is a computer radio, if you want to run them digital or if you can still have analog. There is a bunch of things that you will have to think about when you make the switch.

There are some great FM radios out there and there is always the option to go to a 2.4GHz system as well.

Most radios will work with analog servos and digi servos.

ruffrider28435

so if i go with the 2.4ghz radio i can keep the stock servos? What do you think might be causing that glitch that i have. The truck is about two weeks old.

Argess

Look for loose metal-to-metal contact and try to tighten stuff up, or insulate one piece with heat-shrink, or whatever the situation can allow. Watch for metal-geared servos. Metal Geared steering servos can become damaged in a crash. They still work, but the gears are loose and can cause radio glitching. Loose glowplugs can cause trouble. Low batteries of course.......LOL.


Not likely, but for interest:

You can also improve things by have an elctronic technician adjust the radio. This improves the signal to noise ratio and helps reduce glitching. He needs to re-tune the transmitter for max output power. Only adjust the second from the last inductor in line with the antenna while monitoring the antenna RF on an oscilliscope. Or he could do this while moving away. Far enough and control stops, adjust the induictor until you regain control. Keep repeating until teh distance is maximizied.

The receiver can have it's front end adjusted easily if AM. For FM, just leave it alone. For AM, I just move away from the vehicle with the transmitter antenna down until the vhicle stops responding. I then adjust the front end potentiometer on the reciever until. I get control again. I move further away and keep repeating the whole thing. Or you could use expensive frequnecy counters, etc.

I have done all of this to many RTR radios and have at least elimianted glitching in the range I usually drive. All assuming I cleared up all the usual trouble spots (metal-to-metal contact, etc.) first.

3-172IN MTN

I had a glitch at less than a hundred feet towards a lake and lost my heart for a second. Wow that was a scary day.

I bought the Futaba 2.4GHz radio and no more glitching and it added a failsafe to my system as well. It added a frequency lost failsafe and a low battery power failsafe.

These things can get very expesive when they go awry!!!

ruffrider28435

Do you think its a good possibility that the throttle servo could have a shortage in it. It does not affect th steering just the throttle when you go wide open it has a jerk jerk action then it might go wide open.

ruffrider28435

Will the Spektrum DX3 Radio with Reciever SR3000 DSM 2.4Ghz work with my savage xl?

46u

My Feedback: (3)

Yes it will work. I use to run high end FM then about 3 years ago I went to 2.4GHz and I will NEVER go back to anything else.

ruffrider28435

Do i need to change my servos are will the stock servos work with this remote and receiver?

46u

My Feedback: (3)

No reason the stock ones will not work but there are better servos. A good steering servo makes a BIG difference.

ruffrider28435

I think i found some of my problem yesterday. When i changed the crystals out i put the one for the receiver in the truck and vise versa. Also i found something that was interesting if i have my truck and remote on at close range with the antenna down on the truck has a glitch. Also i found that the longer the antenna the better it responds but i'm still switching over to 2.4ghz remote. I had the glitch with the stock crystals in it before i changed them then i went to 27.195 and was ok for a while and it started doing it. I have another antenna but its to big to go in the hole. Does the hobby shops carry longer antennas for rc radios are do they carry just the stock ones for replacement?

steed2-inactive

I think i know exactly what is wrong and believe it or not its not you reciever its the transmitter!! I had the exact same problem with a little glitching and then slowly it got wirse untill when i hit the throttle wide open it would slowly open but glitch on the way. easy way to check is to switch the servo wires and activate the throttle brake servo with the wheel on your transmitter instead and if it sweeps nice ans smooth you have a bad potentiometer. disassemble your transmitter and you will find a hard green liquid on the throttle brake servo potentiometer that someone at the factory put a little to much on and it seeped inside the potentiometer. clean as much of as possible and the clean the unit with electric cleaner and blow it out with compressed air. here's the kicker. to access the throttle brake potentiometer you will have to cut the wires that go to the steering potentiometer because they are soldered to the back of the board and then are routed through a hole in the board and to the unit. dont worry though just reconnect them and it will work fine. seems like alot of work but it only takes about half an hour. make sure you first try it with the servo wires switched and if it still acts up with the thumb wheel the problem is in the reciever or a bad servo.
-Scott

ruffrider28435

Thanks.

SAVAGEJIM

Just a question, I am not electrically inclined, I only know a bit of what I studied in physics class just to get an "A" in class. I dont apply it now, now is it part of any of my current coursework.

Just curious, As for loose metal to mtal contact, how does that cause glitching and interference? Even in FM radios? I know in electronics, the wave functions and frequencies have some sort of linear energy along the meduim of transfer (wires for example). For metal to metal contacts, I know with linkages, the energy would only be expressed in the amplitude as it vibrates like a guitar string. And if the linkage were vibrating any faster, the harmics would create additional nodes, etc. I dont see ow this creates EM fields to interfere with the electronics, FM, AM, 2.4GHz, etc. Maybe some forward and bakward motion my exhibit themselves to, but nothing that I can think of that would cause EM fields (radio waves and such). The harmonics of the metals touching would be purely mechanical, nothing EM at all, no matter how fast the linkages vibrate.

But then again, maybe I am missing something here. I saw a licensed plumber use two coat hangers and dowse for the water pipes. and I have no idea how water, even though it is dipolar, has enough EM energy to cause dowsing rods, coat hangers, welding rods, wooden sticks, etc. to work.

steed2-inactive

ya i agree i dont understand how that would create unwanted interference?? and if it did then what about metal gear transmissions ? and steel spur gears riding on steel clutch bells? I recently seen this heatshrink tip in a rc magazine but dont see how this would cause glitching? from enelctrical point of view the only way i could see this happening was if the reciever/ servos used the vehicles chassis as a common ground and metal rubbing on it some how induced unwanted voltage. ? but no rc car is designed like this so i dont know????

MadManAndrew

the high pitched noise that metal on metal "clinking" makes is right around the same frequencey our AM radios use...

SAVAGEJIM

Well, noise (sound) is a mechanical phenomenon, not an EM phenomenon. I can see how an EM can be converted into mechanical pressure waves (sounds), the humming of electricity through wires for example, but I unfortunately dont understand how vibrating metals, regardless of the noises (frequencies) they make create EM fields. Unless the linkage wire is magnetized and some how, by means of static electricity, the charge somehow begins to create a circuit some how and a current is created.

Argess

Dowsing.......darned if I understand it, but I accept it works...although one could claim "co-incidence" and sway my thoughts....LOL.

I'm not sure about the metal to metal contact either. When you go to touch your model with a screwdriver, one can easily envision a potential difference between that of the screwdriver (held by you) and the model. There's a static discharge...large enough to cause a glitch. I'm sure the main EMI spike is low frequency and it's harmonics that affect the radio. Hence, the higher GHz radios are immune as the harmonics get so small in amplitude as the frequency of concern gets higher.

I suspect any two pices of metal that touch create a bit of EMI........basically created the same way static electricity is generated when two materials are rubbed together. Since we are talking metals, the voltage doesn't build up, the current (electron flow) is high and EMI is generated. As it is lower in potential (voltage), it is less likely to cause glitching. So transmission gears rubbing, isn't as serious as you touching somthing with a screwdriver. Also, the gears are in good electrical contact when the mesh is good. Have an accident, and those steering servo gears can loosen up and make that contact intermittent. EMI goes up.

Something tells me only iron based metal-to-metal friction can cause sparking (and hence EMI) and bronze-based metals don't do that. Could be why it's the steel components with intermittent touching that often cause problems...i.e. brake rods with loops in the typical off-road buggy.

Mind you I am speculating here.