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What's needed to repair this old Ruddock controller?


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#1 gc4895

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Posted 18 June 2018 - 06:49 PM

I have a Ruddock controller I bought, I believe, back in 1995 or 1996.  It's in perfect condition as it has spent most of it's life in a box.  I would like to make it available to new racers, learning how to drive, but I'm struggling with the sensitivity.  I find the controller too sensitive and difficult to adjust.  This is especially important for new drivers.

 

What do I need to correctly replace the sensitivity "pot" and get this working correctly? 

 

I recently replaced the brake fuse and it's working fine. 

 

Thank you in advance for your help and suggestions.

 

I have a photo to add but I'm unable to post it.  I keep getting the error message of "No file was selected for upload" . 


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Mark Bauer




#2 Pablo

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Posted 18 June 2018 - 07:19 PM

I know nothing about controllers, but I'm having the same photo upload problems you are, Mark. :)


Paul Wolcott

#3 Rob Voska

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Posted 18 June 2018 - 07:54 PM

It is probably curved for a wing car.  If it's the 7-9 band you can change the resistors on each band so it's linear or even lower and give it a slower acceleration curve



#4 gc4895

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Posted 18 June 2018 - 08:40 PM

Rob, thanks! I bought this during my wing car days. It is a 9 band and the copper on this is so thick its never going to wear out. It is very smooth!!!
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Mark Bauer

#5 Ramcatlarry

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Posted 18 June 2018 - 10:51 PM

Are you ohm meter literate?   Check both the trim pot/sensitvity knob and the individual resistors between the bands.

The trim pot has numbers on it and is a common element of Difalco and Ruddock controllers.  The last group of number might end in '500' (50 ohm) or '250' (25 ohm).   Most use the '500' now.  HO use a 100 ohm trim.

The cumulative band resistors should be in the 80 to 150 range for 1/24 racing and twice that for HO and other smaller scales


Larry D. Kelley, MA
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#6 Pablo

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Posted 19 June 2018 - 07:49 AM

Mark, uploading photos is working for me again.


Paul Wolcott

#7 SerfProd

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Posted 19 June 2018 - 08:30 AM

Ruddock controllers work on a divider circuit.  In order to reduce the sensitivity you need to increase the total resistance

of the wiper board. You can also reduce the 10 ohm resistor  but that increases heat.

 

To expand the information....

 

The old 9 band controllers have a progressive resistance on the board in order

to give a proper power curve for racing.  ( more ohms on the first few bands )

 

Increase ohms by 2 or 3 ohms on each band to keep a decent curve and use a 100 ohm

pot to increase sensitivity and drivability.

 

My credentials are I build the Wright Way controllers for Wing Car Racing


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Mike Blevins

#8 gc4895

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Posted 19 June 2018 - 11:54 AM

Mike,

 

I'm OK replacing the 100 ohm pot.  I'm thinking I need one that will handle 5 watts.  Does that sound correct? 

 

That's the easy part.  To be clear, should I also be looking to replace the resistors on the bands as well?  I can measure them for resistance.

 

This time, I was able to attach photos of my unit.

 

Mark

Attached Images

  • Ruddock.jpg
  • Ruddock2.jpg

Mark Bauer

#9 drrufo

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Posted 19 June 2018 - 12:34 PM

As the guy who builds the Ruddock controller and was trained by Dan, I will step in here. The current sense pot is a 50 ohm pot. Don't put a 5 ohm in the sense position. It would not give you enough range. The pot in yours may be bad. Use a meter to check the value across the two outside leads. That will give the value without any reduction. Then check the value using the the two leads and run the knob back and forth. That will tell you if the pot is in good shape. Many of the pots take a set because the racers may not change the position of the knob. 

There are many common parts between the electronic controller currently available , so finding a 50 ohm pot should not be hard

The resistors that are on the left side of the board can be replaced, but you need to make sure they are the right value.

Keep in mind that the transistors are not replaceable. If the controller is hooked up wrong and the transistors get fried, the potting compound makes the replacement impossible.

Keep the bands clean and the controller should be good for a beginner.

 

John Andersen

DR Racing Products


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#10 gc4895

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Posted 19 June 2018 - 01:35 PM

Thank you for your help!  This unit it kept behind the counter at my "local" to be loaned (not for sale since then how could I loan it!) to new racers.  I'm trying to do what I can to help and encourage beginners.  I find that a good controller can go a long way to improving the slot car experience.

 

I'm getting out my ohm meter tomorrow and getting after a thorough check of the unit.

 

Mark


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Mark Bauer

#11 drrufo

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Posted 19 June 2018 - 01:53 PM

Mark, feel free to ask me any questions you have about the controller..

 

John Andersen


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#12 Rob Voska

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Posted 19 June 2018 - 03:20 PM

The discoloration on that pot bothers me.  Might be a bit of corrosion inside.  Also check the extremes full soft and full hard.  Sometimes pots act funny at the end of their range.







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