From: milo@dorm.rutgers.edu (james mielo)
Newsgroups: rec.models.rc
Subject: Re: new R/C car guy has problem, needs HELP!
Date: 19 Nov 92 02:26:40 GMT
Followup-To: rec.models.rc
Organization: rutgers university

In article <cerulean.721362543@access.digex.com>, cerulean@access.digex.com
(Bill Christens-Barry) wrote:
> 
> I need help, please!  I have some questions about an R/C car (a Kyosho
> Optima Mid 4wd that has a different motor put in by the previous owner) 
> that I bought used the other day.  It has a Futaba FP-R102GR 2 channel AM 
> receiver (29.965 Mhz) with a battery eliminator circuit.  It has a speed 
> controller (a Nova 18-III) that allows for continuously variable forward and 
> reverse speeds.  It runs on a 7 x 1.2 v NiCad pack.  

.
>    Anyway, while my son and I were testing the car it developed a problem.  
> It no longer will go in reverse as it would before we ran it into a dirt 
> embankment (with low impact).  I see that the joystick correctly causes 
> green and red leds on the speed controller to light when the joystick is 
> moved to forward and reverse positions, respectively.  However, I hear a 
> clicking kind of sound coming from the speed controller when I try to go in 
> reverse and get no movement.  My son said that putting the joystick into 
> reverse while the car is moving forward seems to deccelerate the car but 
> has no other effect. 


       It doesn't look like the unit was meant to be opened or 
> serviced although I think I can do so nondestructively.  Can I get a 
> replacement relay or will I have to buy a whole new controller?

      If you have a problem with the speed contoller, just send it back to
Novak. They will repair it for a fee.



>    Let me add that the speed controller has two trimpots with markings that
> allow some adjustments.  One is marked "neutral" and the other is marked
> "proportional" underneath and has "hi" and "low" markings indicating the
> effect of turning it in either direction.  I don't think these settings were 
> disturbed by our crash.  Can someone explain what these are all about?

       The pots adjust the amount of current the speed controller gives out
relative to the postion of the transmitter. If you turn the neutral pot it
will change the postion of the neutral setting. Give it a shot. Turning it
one way will cause the motor to slowly go forward. the other way, reverse.


   The lights should go on at full or go off at full ( I can't remember
which)
Just watch the light. If it's on at less then full throttle it should go
off at full throttle and vica versa. I have an older model that doesn't
have reverse and only a red light. So I don't know what the green on does.
I guess it has something to do with reverse. Note that the same should
occur in reverse. Put the car in full reverse if the light is on and
doesn't go off, you haven't hit full revers and need to adjust the pot. 


      My guess is the reverse trimpot is off. Try putting the car in
reverse and watching the light if they don't do what they did during full
forward (I assume forward works properly)then the revers pot is off. Do
this without the motor attached or if it's hardwired to the speed
controller make sure all 4 wheels are off the ground or the car will take
off



  Proportional determines the curve. If linear, a small increase in speed
requires a small movement in the position of the reciever trigger/ stick

     It is possible that the pots are just out of adjustment. It's best if
you get the instructions for the controller or goto you local R/C store for
info
they would know more and be more familiar with the unit you have.



>    Since I bought this setup used and on a shoestring budget I can't afford not 
> to try to fix it.  Any help you can give me will really help me get this car 
> back on the road.  Several more things - if I do need to buy parts, where 
> should I buy them?  Is there a mail/phone order place that carries parts that 
> I can use?

       TOWER HOBBIES is the mail order catalog place. You can find the adds
in most R/C mags. I would also recommend getting a subscription to one of
the R/C car mags. You'll learn alot


  How do I know what is compatible with my car?  Any suggestions 
> on a particular brand or model to use as a replacement?  Finally, I've been 
> told that it doesn't do much good to the brushes in your motor to use
> reverse.  Why is that?
   The brushes tend to seat themselves in one direction. Reverse tends to
be less used so the brushes won't be in optimum contact with the
commutator. SInce the motors are not unidirectional it won't affect the
motor and shouldn't make much of a difference on the brushes either. Just
keep the motor and commutator clean and cool and oil the bearings/bushings
regularly and you shouldn't have a problem.

James Mielo
Rutgers College of Pharmacy '94
milo@dorm.rutgers.edu

 Good luck. I haven't really been in the R/C car stuff since I went to
college about 4 years ago. I use to be on the cuttimg edge and still have
my optima mid, a RC 10 and a 12L
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