13 replies to this topic

[MarkH]

I have four of these Parma 4 ohm controllers. When they were new the trigger action was not very smooth. I sanded down the resistor a bit with block of wood and 220 grit paper. Then I put the 220 between the resistor and wiper to smooth the action out. It worked just fine and all four felt good.

 

I only use these for parties where adults want to be race car drivers for a while. With only three or four "race nights" on them they became real rough and a couple would not return to the brake tab.

 

The party cars are Turbo-Flex with 16D. Power is 12v power supply. A 2 ohm resistor in line at the controller station on the white post.

 

Any ideas how to fix this issue? Should the resistor be on a different post? Do I need to just run full power and gear them down? Is there a better option for a "party" controller?

 

Thanks.

[Kevin Donovan]

My kids do this to controllers, too.

It sounds like your guests are holding the trigger part way down, overheating the resistors.

This will keep happening until you show them how to use full power and also the brake band.

[Eddie Fleming]

The problem you are talking about is one of the reasons for electronic controllers. For years we old timers fought that very problem. It is only worse as the power of the car used goes up. Many different things have been done to try slow down the problem but some maintenance is required with a  resistor controller, or any controller. 
 
Try rounding/angling the edges of the wiper button so it has a ramp to lift it as it moves along the resistor. If you look close the wiper should lift a little and brake contact with the power winding just before it makes contact with the brake band on the resistor. The more the car runs at less than full power the more heat you will build up in the resistor and the more roughness you will develop.

The option is a low cost electronic controller.

[MSwiss]

The Koford M558-3 is a much better controller.

It uses a heavy copper clad circuit board and has thin wire loops between each band that create the resistance.

That wire runs through the inside of the controller and down the controller leads. The heat is thus distributed along a much bigger area.

I do a lot of reduced power rentals and parties with these controllers and they stay very smooth.

[JK Products]

Hi Mike,

 

We have a new resistor I'd like you to test. 

 

Please contact me.

 

Tim

jkp@jkproducts.com

[Ramcatlarry]

I experimented with local slow down methods for my rentals.  The best result was four (3 amp) diodes soldered in series in the black controller line to reduce voltage be about 3 volts.  The polarity is critical to get right.  I tried some in the controller handle and eventually made a "Grey post" so that the white was full power and the gray was for slow down with the diodes between the white and grey post under the panel.  The resistor helps with a 16d, but not with the falcon motors - and the diodes work with both.

[MarkH]

Thanks for the input guys. Sounds like they would be holding the throttle part way. As we all know new people always try to maintain one position so they don't crash as much.

 

Larry, should my resistor, if continued to be used, be on the Black post? The Diode setup sounds better. Can you send me a diagram and diode part number I need to make this work?

[MSwiss]

This might be cheaper, if you thought 9v would be low enough.

 

http://www.ebay.com/...t-/180777043955

 

But I'm not sure it will cure your problem.

 

I get customers in all the time with 4 ohm resistor controllers they got when Parma still sold starter kits.

 

A lot of them stick and the wiper doesn't come back to engage the the brake contact.

[gjc2]

As for the trigger not being smooth; make sure the wiper button is lying flat on the resistor, and try some braid juice on it. 

[Ramcatlarry]

1) Parma controllers use tungsten wire for the resistance coil.  IT CORRODES and needs to be either sanded or lubed or BOTH periodically.  The wiper button is copper and it corrodes and needs to be sanded if it is not shiny.

2) Parma (and other brands) one barrel resistor controllers have not changed much since the were first used for HO and homeset slotcars in 1965.  They are about 25 WATT capable - that computes to about 2 amps at 12 volts DC - Falcons and smaller motors (homeset and slow HO) .  The Parma turbo and other two barrel resistor controllers are rated at about 40 Watts or less than 4 amps at 12 volts DC.  This the 30 ga  armature range - 16D, wasp, contender, and other under $20 motors.

3) Brass on brass - as in the nice Koford units and Prof Motor controllers - have much less corrosion due to dis-similar metal electrolysis.  They still benefit from periodic clean and lube.

 

4) The diodes I use are the common Radio Shack 3 amp size - about 1/4" dia about 1/2" long.  Bigger or smaller can be used. All drop voltage the same.  The 3 amp size is a better size to limit current without excessive heat.  The six amp ones work in a commercial setting as well.  The "chain" is in the white input power line.  The grey post is hooked up with the white wire as the 'chain'  comes from the white to the grey.  Old Difalco and Cidex rental controller systems used the same concept in their rental kits

[John Streisguth]

My first electronic controller I built myself, using a fairly high ohmage HO resistor. Since the transistor handles the load, there was no problem with any sticking. 

[Joe Mig]

On certain class cars I still like my 3, 4, or 7 ohm controllers that I have blueprinted, especially the one with the Fleming hinge.

[MarkH]

Thanks again, guys.

 

I like the diode method. I will get some on the way.

[Samiam]

Flaeming hinge is what I end up with when I try to run my old Gp-20 stuff with my 2 ohm.