Hi all, I am here needing help with something I have hardly any knowledge of (in depth electrical circuitry). I apologize if this is the wrong way to go about it, but I have pretty much exhausted all others means so far.
I have a motorcycle chassis dyno machine that is really old and the manufacturer has stopped supporting it of course. It has an eddy current brake for applying load to the roller drum. It has stopped applying load. The eddy current controller is powered with 240 AC straight from the wall outlet to the controller. Apparently the controller changes the input AC over to DC and inputs amperage into the coils of the brake retarder for variable induced load as needed by operator thru the means of a handheld controller.( 0-20 amps as needed or directed)
This may all be redundant to most of you and I'm sorry if I provide too much info.
The manufacture has helped very little and only has a solution of buying all new very expensive electronics system upgrade. I need help troubleshooting and repairing this controller I have, all the while not understanding the inner workings of circuitry or the system used by manufacturer. I have somewhat determined that it is a PWM control system. The handheld controller seems to work correctly and the coils ohm out correctly on retarder.
I do not need it to work as designed if not feesible to repair, What I mean is, if I can't easily fix this one, I wouldn't mind having a separate independent control system of adding the load. It seems to me all I need is a variable way to apply up to 20 amps DC to the retarder coils
Ok so what I'm thinking is the controller is not changing the input 240 AC power over to DC. The reason I say that is because I have measured 240 into the controller and also coming out of controller, up to the terminal block of coils at retarder. I would imagine this should be DC coming out of controller to carry amperage to retarder coils ??
Please any help or direction would be greatly appreciated. Or anyone interested in personally repairing/troubleshootimg this controller for me, I could send it to you? It has been suggested by manufacturer to check the following......
"I recall a few times where the problem was one of the DS8921 tranceiver chips. These are small socket mounted ic chips with one on the controller and one on the cable connector board in the sensor box. I believe this part is obsolete but you can probably still find them on Ebay and they should be inexpensive. If you want to try that you can just pry the chip out of the socket with a small screwdriver and push the replacement in. Search for DS8921."

Thank you for any tips.

 

OK, what you need to find is the maximum current used to set the maximum torque requirement. It would also be useful to know the maximum DC voltage that would be applied.

Is this dyno load controlled by a computer?? or just a calibrated knob?? Is there a torque measuring system with a display??

We solved a similar problem in another thread a few years ago. Actually, two dynos have been repaired.

 

Thank you so much for the interest in helping us. Unit is a SuperFlow CycleDyn.
So the absorber is set up for 20 amps max and I believe the max DC voltage is 390. I need to verify that.
It is load controlled by means of handheld controller through computer program, no knob.
It does have a load cell measuring system for torque on the eddy current absorber.

 

OK, so there is a computer involved?? In some other systems a computer was used to control the brake application to run thru a series of speed/torque points . Apparently the original system did that with an analog control system.
So what it looks like is that a digitally controlled DC power supply with quite a voltage range and 20 amp capability is required. The good news is that for powering an eddy current brake the power does not need to be very clean and well filtered.
Possibly just a phase-controlled DC supply can work.
WHAT MAINS SUPPLY is available?? Single phase or three phase??

 

Yes there is a computer and all test can be auto run, some test do have set points with programmable holds at specific rpm’s, load or speeds.
System has a handheld controller for operator, a computer monitor and keyboard, a huge free standing “sensor box” with attachment points for all the different cables and harnesses with 2 big circuit boards inside, another smaller circuit board on frt on dyno unit along with starter motor and battery, and finally an eddy current controller mounted on the side of absorber. Unit has a direct 240 AC single phase line feeding the absorber and a separate 110 AC volt line for sensor box and computer system.
I was so hoping to find a way to trouble shoot the handheld controller, to be sure it was sending the signal to apply load to absorber. But the factory is saying the unit is so old they don’t have any info left to help diagnose that signal. They did say it was a pulse width modulation signal and would be complicated to measure. I really don’t know if the trouble is the command signal or the absorber controller. We did verify the eddy current coils seem to be fine. We don’t seem to be getting an increase in DC voltage out of absorber controller.

 

Verifying the output of a PWM circuit without any information or test equipment is a challenge indeed.