The Shop > Tools
Real Bull Mini-lathe Speed Controller Woes
Stilldrillin:
Hi Ross.
So sorry, I was no help to you. Boxes of wires, and pretty coloured blobs are baffling to me...... :scratch:
Posting here is the right thing to do. These lads got me up and running again. :thumbup:
David D
hopefuldave:
Hi Ross,
If that's as I suspect a Chinese cheap clone of the KB controller board, there will be a row of small preset potentiometers at the top of the board ( top as shown in the pic), there will be three together marked Min, Max and Acc, these unsurprisingly set the minimum, maximum and acceleration speeds.
If the control pot is correctly connected (see earlier in the thread) try tweaking the minimum preset first, it should be possible to stop the motor, then try the maximum preset.
The control potentiometer should have 10V DC across it, the wiper should be variable from 0 - 10V, if this isn't the case check at the P1 andP3 pins for 10V DC to determine whether it's the wiring / connectors between the PCB and the control.
A VERY IMPORTANT WARNING: The control's pins on the PCB are NOT isolated and can be at a dangerous voltage, BE CAREFUL, insulated probes and multimeter plugs are essential. If any of the control leads short to earth IT WILL DESTROY THE PCB so ensure you use a plastic-shaft pot and insulate it well, heatshrink or rubber sleeving over the pot terminals. This is true of both the clones and the genuine KB boards.
Also on the PCB are presets for motor current limit and IR compensation, if you adjust these you need to a) know what you're doing and b) measure the motor current, incorrect IR comp will cause "cogging" at low speeds, current limit set too low will reduce the motor voltage when the armature current rises beyond what it thinks is the correct max current through the motor...
I hope that helps rather than confuses!
Dave H. (the other one)
velocette:
Hi All
This topic keeps on cropping up on MM Can I add a pointer for anyone who wants to learn more on the workings and setting up DC Controllers is to go to this site and download a manual or three.
Sure it not specific to Asian controllers but has been a great source of info that I have found helped my understanding of these controllers.
http://www.kbelectronics.com/Variable_Speed_DC_Drives.html
Eric
John Rudd:
KB manual specific to this particular model here....
http://www.kbelectronics.com/manuals/kbic_manual.pdf
Page 7 deals with adjustments....
Ross:
--- Quote from: John Rudd on September 05, 2015, 04:58:54 PM ---Ok,
The speed control connections,
Looking at the pot from the front(the spindle knob end...), the left tag goes to P1, the right tag goes to P3 and the centre tag goes to P2.
The motor leads go to A+ and A-, with mains input onto L1 and L2.
If you disconnect the motor from the two A connections, disconnect the speed pot from P1,2&3. Now connect P2 to P1with a short bit of wire, measure the voltage with your meter connected to the two A tags...What is the reading?
Disconnect the bit of wire, connect it to P2 and P3, what does the meter read across the two A tags?
Ensure you switch off at the mains when you make any changes!!
--- End quote ---
Ok So, I'm getting 0 volts for both of those tests? Seems strange?
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