Warco WM180 motor control

[modeng2000Participant @modeng2000]

I am trying to find information about the motor control circuit board fitted to my Warco WM180 lathe. The user speed control on the front of the lathe used to take the chuck speed down to zero as suggested by the speed selection label however now I can not reduce the speed below 200rpm.

 

There are two preset potentiometers on the cct board, one for min revs and the other for max. The min rev setting is at the lower limit of rotation so there is no more adjustment available.

 

The information I have from the circuit board is that it is by Best Control Inc (Taiwan) and is a BC 2000TA DC motor control board.

 

I have in the past asked Warco if they would supply me with information about setting up the motor control board but to no avail. It seems a bit over the top to take the lathe back to them or to call them out for a service call to adjust a nominally working machine.

 

Some while ago I used the lathe to wind the solenoid coils for my ME Clock but I couldn’t now as it runs too fast.

 

John 

 

 

 

 

 

 

Edited By modeng2000 on 28/10/2010 16:39:25

[modeng2000Participant @modeng2000]

[Chris KellandParticipant @chriskelland71558]

Hi John,

 

I take it you have rung Warco?

 

If not give them a ring 01428 682929 extension 209  and ask to talk to Eric or Chris they are the tech engineers and very helpful.

 

 

Chris.

[Chris KellandParticipant @chriskelland71558]

Hi John,

 

You could also look at this link, there is a bit of info on the control board.

 

http://andysmachines.weebly.com/index.html

 

 

Chris

[john swift 1Participant @johnswift1]

Hi John

 

if Warco can’t help

 

have a look at the control board

If your lucky the speed control board will have preset’s for  the maximum and minimum speed marked on the pcb 

(make a note of the position before adjustment of the minimum speed)  

 

if not and you have the wiring diagram for you machine

you could disconnect the +10v or +12v supply form the speed control to prove

that with a control voltage of 0v the speed is 0 rpm

 

two diodes can be used to give a 0.6v volt drop to the control voltage to give a small reduction in speed

 

I’ll post a diagram

 

 

       John 

  

Edited By john swift 1 on 28/10/2010 17:48:41

Edited By john swift 1 on 28/10/2010 17:49:22

[john swift 1Participant @johnswift1]

missing from previous post

 

with the speed control fully anticlockwise the control voltage may not be zero

(the mechanical end stop may stop the wiper reaching the end of the resistive track)

 

also the minimum and minimum speed presets interact

 

so far I can not find the circuit of KB Electronics speed controls used in your lathe

 

 

     John 

 

 

 

 

[modeng2000Participant @modeng2000]

Thanks for the replies, all very interesting.

The minimum preset is at minimum so I can’t get any more reduction from there. If the max and min resets interact I might be able to ‘shift’ the speed control range down by careful adjustment but don’t hold much hope for this aproach. Something has changed because I was able to reach almost zero speed when the lathe was new.

 

Chris, I’ll ring Warco again, it is now some time since I last tried and perhaps I did not speak to the best person then. The link to andysmachines is quite informative, thanks.

 

John, I have tweeked the speed presets and know where they were before touching them. however this has not helped to reduce the lowest speed. I was hoping for a circuit diagram of the pcb so I could understand how the speed presets function.

 

John

[john swift 1Participant @johnswift1]

Hi John

 

found a low res circuit that may help

   

 

the max speed preset pot sets the voltage across the speed control

 

the min speed preset adjusts a bias voltage to the first op amp

 

it may be worth checking all the electrolytic capacitors on the board

 

( if you can measure the ESR ) 

 

 

      John

Edited By john swift 1 on 28/10/2010 22:03:27

[modeng2000Participant @modeng2000]

Things are not quite like your circuit John. It turns out that the 3 pots, Max, User control and Min are all in series across the supply rails. So with the Min at zero volts I suspect there has been a change elsewhere in the circuit.

 

I shall go round with my Fluke and make sure that the zero setting is indeed zero volts.

John

[john swift 1Participant @johnswift1]

Hi John ,

 

so far i’ve only found a picture of your control pcb

 

but have not found the circuit of it or similar looking kb electronics control

 

it looks like you will end up reverse engineering your board !

 

as I did a the start of the year , with my CL300 minilathe

 

    John

[Billy MillsParticipant @billymills]

John

 

Don’t know your machine but wonder if there is an opto tacho connected to the corner connector. Would suspect that a dirty or failed slot sensor could produce the fault. With no tacho signal the controller would run above the set min speed. Would never rush in to modify stuff without understanding what we are dealing with.

 

Regards

Alan

[modeng2000Participant @modeng2000]

Alan,

 

The opto tacho is working normally in that it displays the actual spindle speed changing as the cutting load varies. As far as I can tell the tacho is independant of the motor control circuit.

 

John

[modeng2000Participant @modeng2000]

John,

 

Now I have a fair idea as to what is going on with the motor control I could end up reverse engineering. At least it seems to use a quad op amp LM324, one of my favourite chips.

 

John

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