strange radio/servo problem

[mrwill]

ok, had my new storm truggy out playing today, had to replace the stock radio with a jr xr3 fm radio, now I am thinking it may not have been the radio.replaced the steering servo with a 5645mg but left the throttle stock. started the day with new batteries. first off the bat it runs out about 40 yards goes to full throttle and holds a wheelie for 40 feet into the fence ( I have a fail-safe) pull the old batteries and put in new ones figuring the old ones were bad.check every thing it is ok, go out and run for 1/2 tank, and bring it in when I notice the engine is surgingcheck it out n.p. start it, it goes to full throttle and starts to run away, but I can steer it so I bring it around and then I get control again and shut it down. bat throttle servo?? did the same thing with the stock radio. what would be a good replacment servo??

 

[Monkey Wrench]

Could be a bad throttle servo. Have any others you can throw in there just to compare? Have you tried running it without the failsafe? It almost sounds like someone is jumping on your frequency. Hmmmmmmm.......

 

[olds97_lss]

I've had a couple throttle servo's do that. It would work fine for a few minutes, then just get all weird. Those are now "parts" servo's.

 

[HeartBreak]

I've currently got one that will work fine in one direction, but act like anti-lock brakes in the other. Thankfully, it's in the direction the brakes are, so it really is an anti-lock brake. It also pulses at center, too. I guess I should have put a thin pad between the bottom of the servo and the chassis.

Oddly enough, it was mounted in a Storm buggy.

 

[olds97_lss]

That's what mine started doing... then it would slowly creep to WOT.

Although, you may have your EPA going further than the servo can stand. They bounce like that when your trying to make them apply more force than they are built for. At least most of the ones I've had do that when I have the EPA going too far.

 

[HeartBreak]

My EPA wasn't set that far. In fact, it was set to around 90% of the travel. Any further, and the buggy would do donuts if I wasn't paying attention. I think what happened is the servo more-or-less got vibrated, due to the bottom of the case making 'just enough' contact with the chassis to rattle it. Kind of like an ultrasonic cleaner, minus the fluid.

edit; update:

Replaced the POT in the servo (the little doohicky that tells the servo where it is). Determined that it is NOT the POT. The twitching persists, however it is now only when the servo gets to where it's going, regardless of direction or distance.

In other words; it randomly twitches during "Hold position" mode.

Conclusion; the controller board has a loose component; not going to pursue repair further. Cheaper and easier just to replace it.

Cause of damage; not properly isolating the servo against vibration.

I'm just glad it's a Hitec 625MG and not a $100+ servo.

 

[mrwill]

Could be a bad throttle servo. Have any others you can throw in there just to compare? Have you tried running it without the failsafe? It almost sounds like someone is jumping on your frequency. Hmmmmmmm.......

well , the problem is there is nobody around (lunch time at a field). I am going to pick up a new servo (30.00) and see what happens. I hope that this solves it... at least it isn't a wasp so I know it is fixable lol

 

[rotarycaviar]

New guy here, but my car suddenly has a similiar issue. Out of nowhere, just goes full throttle, with no controls whatsoever. New batteries etc., and no one within miles of where I race. Anyone ever figure this one out?