18 replies to this topic

[ThunderThumb]

Controller has power when trigger is in off position , switched controllers and everything is good , so it must be in the controller , any suggestions , thanks

[SoCal Bill]

Is the button in the right position (brake band)?  Check if the blast relay is stuck.

[Paul5097]

Clean the wiper board with a q-tip and lighter fluid. Pay close attention to the spaces between bands, particularly the first one.

[Eddie Fleming]

Is the car running at high speed or low when the trigger is not pulled?

[Ralph Josey]

Try cleaning the break post, make sure the trigger is making a good clean contact when in the resting position on that post

[ThunderThumb]

Car runs at full and or high speed with no trigger , when full trigger is applied you hear the full power blast relay click so I assume it is not stuck , will try cleaning the wiper board , thanks

[ThunderThumb]

I just bench tested it after cleaning , still the same , motor runs when trigger is off , motor revs a bit higher when wide open as the full power blast relay seems to be working

[Phil Beukema]

Jim Difalco will come along and get this straightened out.

[ThunderThumb]

Thanks , I also emailed him

[Phil Beukema]

Be sure to post his solution!

[ThunderThumb]

For sure

[Ramcatlarry]

Your symtims are typical of a blown transistor.  A small resistor near the wiper board will likely look burned - replace both.

[Alan Dodson]

Larry is right, I experienced the same thing on a controller I bought on eBay. It's an inexpensive and easy fix, just make sure to make a drawing of the wiring going to the transistor and get the transistor polarity right. The Difalco replacement transistor comes with the resistor that Larry mentioned. Also use a lower wattage soldering iron or turn it down if it's adjustable.

[Jim Difalco]

Ok everybody, here are the easy ways to diagnose issues with your Difalco controller.

 

 

Power on without pulling the trigger and your car gets near full power:

 

This could be the diode or the full power transistor(s). Since it is easy to check the diode just unscrew the one side of the diode from the heatsink (older models) or unsolder  (Genesis 1) or cut (Genesis 2) one side of the diode. Now track test the controller and if the problem disappears the diode was the issue. If the problem is still there replace the transistor(s). HINT: If the resistor in holes "D" and "H" (or "D" and "F" on traction models) is visibly burned then it is the transistor(s) not the diode. Just because the resistor looks good does NOT mean the transistor is ok. The resistor blows if you continue to drive the car after the transistor is blown. If you cut one side of the diode and the transistor is the problem simply solder the diode lead back together.

 

Power on without pulling the trigger and your car takes off slowly. (very rare):

 

This is caused by a high resistance short circuit between the first band and the dead (resting) band. This is a combination of wiper button dust and lack of maintenance that builds up and causes arcing between the bands. This does not happen on my newer controllers with the ESP brake relay. On older controllers simply scrape the fiberglass slot before the first band with an x-acto blade. Clean your bands with lighter fluid and lubricate them with a small film of braid juice.

 

Your car seems slow and the heatsink is hot. (very very rare)

 

You have managed to blow your power relay. If the relay is blown then the transistors are running all the time which causes the excessive heat and slow speed. This can only happen on my controllers with the gray cable. Older Emotion models with the heatsink just below the handle still have the full power contacts to provide full power to the car.

 

You pull the trigger to the first band and get a very fast response with little change when turning the sensitivity knob (very rare)

 

The resistor in holes "D" and "H" (or "D" and "F" on traction models) is physically damaged with a broken lead or bad solder joint after being replaced.

 

Intermittent brakes:

 

This is my pet peeve. It only takes a few minutes to remove your front handle and polish up the brake contacts with an emery board. If your car occasionally comes off in a turn because you thought you dove in too deep it may be your brakes! Clean them!

 

No brakes except at full brake position:

 

You probably blew your brake rheostat. Grab your ohmmeter and see if you have resistance at half brake position right on the brake rheostat terminals.

 

 

Other troubleshooting hints and rumors:

 

1) Relays do not blow closed. (Extremely rare) I have never personally seen a blown relay cause a short inside the relay or seen relay contacts weld closed. You have to remember that my relay only actually switches a small amount of power. This would be the small voltage drop caused by the transistors.

 

2) I do not put fuses on my relay outputs! An occasional controller maker declared to me that his controller did not use electronic or regular fuses on his relay output, like he thought mine did. My fuses are there to protect the transistors and components. Putting a fuse on a relay or MOSFET outputs, like 3rd Eye, adds resistance and voltage drop to the circuit and reduces track power to your car. When electronic fuses blow and reset the resistance generally rises and causes more voltage drop. The most important thing a controller needs to do is deliver full power to your car, which is why I still use expensive 10 gauge wire.

 

Oddly enough all these troubleshooting tips are in my instructions. Yes, you could have lost your instructions or not read them like many. These tips are also available on my website troubleshooting section or you can email me for new instructions. If you email me tell me your model number and send a picture or two so I can indentify the vintage and send you the correct instructions.

 

 

After 30 years making controllers I have seen other weird problems turn up, mostly because of abuse or lack of maintenance. But they are so rare they are nothing to worry about.

 

Hope this helps. Thanks for using my products. Back to work for me.

[ThunderThumb]

I disconnected the the diode by removing the screw so it is not grounded and it does the same thing so I assume it is the power transistor , thanks

[Pappy]

Since I have two Difalco controllers I made a copy of Jim's diagnosis instructions and it is now in my slot car box.

 

Thanks Jim

[Phil Beukema]

ditto

[ThunderThumb]

As I mentioned I dissconected the diode and same problem , I just replaced the power transistor and that was it , the sensivitity and brakes work and the motor shuts off and works as it should through the wiper range while pulling the trigger and the full power blast relay works , thanks Jim and everybody who replied

[Jim Difalco]

This is exactly how I like to do my repairs. Where racers can just go through a few steps, diagnose and quickly and inexpensively repair their own controllers.

 

I will, of course, be here to do repairs for racers if needed. Please email me for my service worksheet before sending in your controller for service. It asks for all your contact and payment information, has pricing for various upgrades and just makes it easier to do your repair in a timely manner.