RC truck that won't turn

[FordGT90Concept]

So, it goes forwards and backwards and the steering motor auto-corrects for when it is off center but it won't steer via controller command. I took the lot apart and everything looks good.

I was going to take it up to Radioshack but I discovered the guy that worked on my other RC cars passed away so I'm pretty much on my own. :(


Anyone have any ideas? I really want to get this truck working again. It worked this morning but quit today. The truck has nostalgic value so its not something I would just pitch and replace.


Edit: after some research, it sounds like the channel used for steering isn't working. Anyone got an idea how to correct that?

It appears to have 27.145 MHz radios.

[Solaris17]

you should first try by replacing the transmitter. If that doesnt work try the servo/motor for the steering.

[FordGT90Concept]

I know for sure it is the controller. I have a similar controller on the same frequency that works but unfortunately, it handles completely different so it won't work as a permanent solution (4WD truck versus tracked car). I basically need to either replace the innards of the existing remote or find a new one with 27.145 MHz controls.

[dr emulator (madmax)]

i'd say ask sir_real he dealt with alot of rc stuff
to me it sounds like the controllers potentiometer isn't connected ,take it apart and stick a multimeter on it and press the stick up and down (should change resistance)

[FordGT90Concept]

I could take a pic of the circuit board. Everything on there looks like it is connected so I suspect something inside one of the capacitors or other component failed. I don't know how I would even a multimeter in there to test except on the pins sticking out the backside.

[TechnicalFreak]

Is it one of them that you have to build yourself or is it a ready-to-race type of car? I know I once had a similar problem, and the small "gears" inside was worn off. They replaced them with small alu gears. And on another very old car it just broke, I just replaced it.

However, if it is one of them with everything ready made, then it could be the electric engine that is "stuck", try powering it straight of an AA battery or two to see if it rotates by itself. Sometimes the steering links get jammed/stuck and they don't turn - just release the electrical engine and move them to see if that works.

Any pictures of pcb and the main steering? Oh.. And what brand is the RC car??

[dr emulator (madmax)]

yeh take pics,
but i'm still thinking it's the mechanical part of the variable on ya stearing stick,
as i said sir_real over at tpu fixed a similar problem i'll see what he says
sometimes though he's hard to get hold of

[FordGT90Concept]

Is it one of them that you have to build yourself or is it a ready-to-race type of car? I know I once had a similar problem, and the small "gears" inside was worn off. They replaced them with small alu gears. And on another very old car it just broke, I just replaced it.

However, if it is one of them with everything ready made, then it could be the electric engine that is "stuck", try powering it straight of an AA battery or two to see if it rotates by itself. Sometimes the steering links get jammed/stuck and they don't turn - just release the electrical engine and move them to see if that works.

Any pictures of pcb and the main steering? Oh.. And what brand is the RC car??
It is a ready-to-race type. Here's one of them going on eBay:
http://cgi.ebay.com/WILD-HORSE-RADIO-CONTROLLED-4WD-OFF-ROAD-TRUCK-NICE-/370371111079

I took the steering gearbox apart and cleaned it up (there was fine sand in there), all the gears are in good condition and I lubed it up. The electric motor functions fine as well in and out of the gearbox. The truck works fine using a different 27.145 MHz remote (unfortunately, it is a completely different kind of truck so that isn't a permanent solution).

It's a Radio Shack branded Wild Horse.


yeh take pics,
but i'm still thinking it's the mechanical part of the variable on ya stearing stick,
as i said sir_real over at tpu fixed a similar problem i'll see what he says
sometimes though he's hard to get hold of
The way the steering is designed, I doubt it is the problem. It uses a sliding contact over a circuit board with 4 contacts. I'll take pics at some point today...


Edit: Here's pics:
http://img.techpowerup.org/100502/100_7632.jpg
http://img.techpowerup.org/100502/100_7633.jpg
http://img.techpowerup.org/100502/100_7634.jpg
http://img.techpowerup.org/100502/100_7635.jpg
http://img.techpowerup.org/100502/100_7636.jpg

[TechnicalFreak]

I think what you should do first is get some electronics grease, some chemical alcohol and some tops.

Contact surface only, no other parts:
When looking at the picture of the part for steering, start by wiping off excess grease and any "plastic dust". After that, clean it with the chemical alcohol. And when you think it is clean enough - test it out and see if it works. If it does, just take a smaller amount of electronic grease and put it around the contact surface.

Also, if you have silver paint, the type that can lead electricity then use that. It works better than copper, or if you are skilled with the soldering iron - put some tin on it, works great too.

[theJesus]

Clean underneath your fingernails while you're at it, too :p

[FordGT90Concept]

I think what you should do first is get some electronics grease, some chemical alcohol and some tops.

Contact surface only, no other parts:
When looking at the picture of the part for steering, start by wiping off excess grease and any "plastic dust". After that, clean it with the chemical alcohol. And when you think it is clean enough - test it out and see if it works. If it does, just take a smaller amount of electronic grease and put it around the contact surface.

Also, if you have silver paint, the type that can lead electricity then use that. It works better than copper, or if you are skilled with the soldering iron - put some tin on it, works great too.
I cleaned up both contacts and the slider. The red light goes on when doing the throttle and it stays off no matter what I do on the steering slider. It gets between 6 and 7 volt on the good one and nothing on the bad one.

...

I noticed there was PNP or NPN switch there which branches off to the steering switch so, I though, maybe you can't steer unless you are going forward/backwards. I tried it, and sure enough, it worked. XD

Silly me. (slap)


Now I need 4 9v batteries...

[theJesus]

LOL, you never tried that in the first place?

[FordGT90Concept]

Usually they can turn without moving, apparently not that one. It's been a long time since I used it.

[TechnicalFreak]

Usually they can turn without moving, apparently not that one. It's been a long time since I used it.

It has to be a proportional radio controller if you want it to do that.
Not all RC models can do that, if and when they do, they are always in the more expensive price range (depending on who ever made it).

However, I had a car from around the 80's from UK, was given to me as a gift. Runs on "normal" batteries C or D cell, can't remember, but that car had a proportional radio control - I could have the car completely standing still and I could move the wheels. It did not have opengimbal sticks, but a steeringwheel and 2 buttons for forward/reverse.


EDIT: I also had a Wild Willy (willys jeep) RC car, that one is controlled just like your car.

[FordGT90Concept]

My (also Radio Shack brand but much newer) Hot Machine II can turn left and right while sitting still. It was about $50 new. I think most of the newer ones can steer without moving but at lot of the older ones don't. It might be because the steering motor is not strong enough to overcome the friction of turning those large tires without moving so they design that into the controller to not wear out the steering gears.

[FordGT90Concept]

Any ideas of what could cause the range of a remote controller to be very short (3-4 feet) that is not the 9v batteries? This is a different RC car than the one above, by the way.

[theJesus]

Yes. A wall.

:p

[FordGT90Concept]

Unfortunately, that's not it. :(

[theJesus]

Are you sure? It could be an invisible wall.

lol, seriously though, the only thing I can think of is radio interference or bad antennae

[FordGT90Concept]

I think it would have ran into it, followed by me so, unless it is an invisible moving wall, I can't see that being the case.


How would an antenna go bad? Both are properly screwed down and neither appear to have any damage to speak of. Know anything that would make a good substitute for an antenna? I have a relatively small guage (like 20-24) coil of PVC jacketed wire somewhere. Would that to test if the antennas are bad?

[theJesus]

Other than physical damage or improper connection, I can't see them going bad either. Do you know what frequency is used for the communications?

[Wile E]

Bad cap or mosfet?

[theJesus]

Wile E brings up a good point. I find that replacing a standard baseball cap with a nice top hat results in better communication.

[FordGT90Concept]

Bad cap or mosfet?
Hmm, I didn't look that closely at it, perhaps I should...


Edit: I checked and none of the capacitors look like they have damage although it is hard to tell because they go in one side and out the other instead of being in and out on one surface (blow out surface on top).