trouble shooting Futaba Junior

[Clayton]

I have an old school Futaba Junior controller that wil not operate the motor of my RC10. The steering works, it just will not run the motor. I know it's the controller, I have already used a different controller and different crystals and the same RC10 works flawless, Any help please.

Thanks,

Clayton

[Coelacanth]

If you reverse the channels by switching plugs in the receiver, does steering work when you play with the trigger? Does the motor do anything when turning the wheel?

[Clayton]

Reverse the channel by switching plugs.....Hmmmm? Do you mean reinserting the crystal in the controller the opposite its is now? Sorry this RC stuff is all fairly new to me.

[bearrickster]

unplug the sterring servo and plug in the speedcontrol were it was and see if it works?

[Coelacanth]

Reverse the channel by switching plugs.....Hmmmm? Do you mean reinserting the crystal in the controller the opposite its is now? Sorry this RC stuff is all fairly new to me.

What bearickster said...you have two plugs going into your receiver; one from the steering servo, one from your speed controller. Swap them and turn on the radio/car and see what happens, then let us know the results. Troubleshooting 101.

[Clayton]

Got it!! I'll give it a try and post the results tomorrow.

Thanks for the help!!

[Coelacanth]

Basically, if you swap the plugs and pulling the trigger makes your wheels steer, then you know your radio's throttle function is working & communicating with the receiver & servo.

[Clayton]

Ok, I did the switch-a-rooney. Now the steering wheel operates the throttle and the trigger switch (throttle) does not operate. I do here a slight buzz from the steering servo. So it appears the problem lies with the trigger switch in the controller. I did not break it apart yet, should I look for anything specific when I do?

Thanks

[Coelacanth]

Good troubleshooting, now you know where the problem lies. Unfortunately I've never fixed a wonky transmitter trigger before. Anyone else have experience with that?

[8rad]

Unfortunately transmitters are usually BER(beyond economical repair). Magnum juniors are pretty cheap on feebay.

If you dont want to go that route then I would break it open and see how the throttle operates. I have never opened one myself but I would imagine it is just a potentiometer connected to the trigger with a linkage of some sort.

If this is the case, you should have 3 connections on the pot. 1 for supply voltage(probably 5 volts), one for control voltage and 1 for ground.

If you have the supply voltage measure the voltage on the center connection of the pot it should vary between 0 and 5 volts depending on the position of the trigger.

If there is supply voltage and ground but no control voltage take the pot to an electronics store and try to match it up. But make sure you get the same value of pot. There are no substitutions here.

If the pot seems fine I would throw the radio in the bin and get a used one from feebay.

Hope this helps.

[Coelacanth]

I have an older Magnum Junior that I received for parts. If you have the same transmitter and want to muck around with the internals, you're welcome to it. But like 8rad said, it's probably not worth the hassle. You can get a whole new modern radio system for under $75 I think.

[Clayton]

I'm going to break it open and play a little, nuttin to lose. I'll post what I find.....and the adventure begins!!

Thanks everybody!!!

[Coelacanth]

I'm going to break it open and play a little, nuttin to lose. I'll post what I find.....and the adventure begins!!

Thanks everybody!!!

Clayton, sgirouard just posted a Magnum Junior radio & receiver for sale, in case you weren't able to get yours working.

http://www.rc10talk.com/viewtopic.php?f=6&t=22106

EDIT: I see you haven't made 25 posts yet so you won't have BST access, but you could PM him. I'll let him know about this thread.

[Clayton]

Opened up the controller, traced the problem (maybe) to the forward reverse button on the top of the controller. Not sure what to do from here but to save it for parts. The control panel looks to overwhelming to tackle. Maybe some day when I am really bored??

[Coelacanth]

Troubleshooting circuit boards is never worth the effort unless you're very skilled with a tiny soldering iron. I wouldn't attempt it unless I was willing to throw it out.