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tony_w
Alabama, United States
Cat F30 Serial 5DB 1990 model. The line controller drops out at slow speed. The drive motors will run fine at full throttle. This is a lift I bought at a salvage yard and I am trying to repair. I had to replace the accelerator pedal sensor and all the diagnostics tests pass. I noticed in post [url/email removed] that the current limit can be set. Does anyone know how I can check/set the current limit for slow speed operation.
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edward_t
North Carolina, United States
don't you get a code on the dash when it stops running?webhome = forktechs.com
tony_w
Alabama, United States
No the dash readout still reads 9. The line controller relay opens and you have to turn off and back on to reset.
roldann
nuevo leon, Mexico
i would make sure to have a good battery (doing a relife test). contactor coil (doing a pulling test) and also check the driver output from logic card, directly from pin p2-6 by using a voltmeter.
roldann
nuevo leon, Mexico
cheking first the wires from locgic card to contactor coil
tony_w
Alabama, United States
Connections to relay are good. When it stops the pin on the controller boards goes to 36v, when running the pin is 0.9v. Battery voltage at the fuses is 36.4v with motor running. The lift sat outside in the weather for several years. The problem is getting less repeatable with time. So maybe the current in the drive motors is fluctuating and the scr circuit is detecting this and feeding the info back to the controller board. As I run the motors more the brushes make better contact and problem happens less. It only does in the slow speed mode. It never stops when the bypass relay is energized.
edward_t
North Carolina, United States
-MAY-be... have you blown the brush dust out of the drive motors? and checked for shorts to frame on all the power cables and controller heat sinks? webhome = forktechs.com
tony_w
Alabama, United States
Blown out the motors with air hose. The resistance from frame to motor leads 1.2 megaohm. Also 1.2 megaohm from heat sink to frame. Battery voltage at rest is 38.4 volts. I have the lift on trailer in my garage and cannot extend the mast fully. I have the lift jacked up so the the drive spin freely. The voltage at the fuses with accelerator at maximum is 35.4 volts. I disconnected all the connectors from the controller board and sprayed them with contact cleaner. No help, problem still there.
roldann
nuevo leon, Mexico
assumming that all the wires are connected at their right place. i still think the card is not doing its job, since it is cutting the volt. to contactor coil (B-) and not displaying a failure code.
roldann
nuevo leon, Mexico
made a mistake. i told you to check pin P2-6 this is not, the correct is P2-15.(B- to line coil)
tony_w
Alabama, United States
Yes, I do have a wiring diagram, but thanks for the offer. It may be the controller card. Yes the correct pin is P2-15 and no problem I can use all the help I can get. I did get the lift off the trailer this weekend. I had to pull it off with the tractor. I hooked an oscilloscope and checked the pulses to the motors. I get a good pulse stream to each motor. With the lift jacked up so that the drive wheels are not touching the ground I can run the motors at a slow speed for several minutes and the line control relay never drops. However once I press the accelerator more than about 1/3 down the line control relay drops and the motors stop. The interesting thing is the pulse stream is still working the motor relay is still energized and power steering pump relay is still energized. Everything is just the way it should be expect the line control relay is not energized. If you manually engage the line control relay the motors work fine. I am still going to try some different tests.
controlelectric
Shropshire, United Kingdom
Hi Tony,controlelectrics.uk@gmail.com
tony_w
Alabama, United States
I think I have finally found the problem. I put an oscilloscope on the power pin of the control board and there were voltage spikes on the pin. The voltage spikes were only there when the drive was in slow speed mode. Full throttle and the spikes went away. I ordered and replaced the large 22000 microfarad capacitor and the problem went away.
edward_t
North Carolina, United States
Tony, thanks for coming back and letting us know what it was...webhome = forktechs.com
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