The Shop > Tools
Real Bull Mini-lathe Speed Controller Woes
Ross:
Hello Fellow Modders,
It's been a while hope you are all ok,
I've recently refurbished my trusty mini-lathe, I've replaced the headstock gears and installed taper bearings complete with a repaint. All was going swimmingly until it came to the electrics. Upon disassembly I marked all the cables that connected to the main board so they went back in the correct places. Re-assembled the front panel went to power on and all ran as it should, after 5mins of constant running it went pop! speed controller dead, no fuse blown plug ok but tripped the electrics.
So I replaced it with a spare board ("Repaired") But when the lathe was powered up it runs but the speed control switch only varies the rpm by around 50rpm's so I assumed that is board was broken in some way as it had been previously been repaired after blowing.
I decided to shell out and buy a fresh board from Amadeal, plugged her in and exactly the same is happening, RPM's barely vary and the lathe runs own its own you can only stop it with the E stop!
I'm at my witts end! is there something I should be adjusting? surely the boards should be set from factory?
I have attached pictures and a video of the problem any pointers would be great.
Ross
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John Rudd:
Hi Ross,
Im fairly conversant with the RB speed controller, so theres a fair chance the problem can be sorted....
Firstly, have you got a multimeter? That would be a real boon in diagnosing.
Secondly, disconnect the motor from the A and A+ connections on the board. Then take a 100 watt light bulb( mounted in a holder with some flex attached to it). Now connect the ligh to the A and A+ connections...Adjust the speed pot from 0 to 100.... Does the light bulb go from dim to near full brightness? Smoothly?
If it does then the motor is suspect.
If the lamp behaves as the motor, then either the wiring is incorrect or the board is needing adjustment or is faulty...
Report back your findings and we will proceed further...Dont forget the dvm question plz.
philf:
Ross,
I know nothing about mini-lathe electronics but are you absolutely sure that the speed control pot is connected properly?
Phil.
Ross:
--- Quote from: John Rudd on September 05, 2015, 12:10:00 PM ---Hi Ross,
Im fairly conversant with the RB speed controller, so theres a fair chance the problem can be sorted....
Firstly, have you got a multimeter? That would be a real boon in diagnosing.
Secondly, disconnect the motor from the A and A+ connections on the board. Then take a 100 watt light bulb( mounted in a holder with some flex attached to it). Now connect the ligh to the A and A+ connections...Adjust the speed pot from 0 to 100.... Does the light bulb go from dim to near full brightness? Smoothly?
If it does then the motor is suspect.
If the lamp behaves as the motor, then either the wiring is incorrect or the board is needing adjustment or is faulty...
Report back your findings and we will proceed further...Dont forget the dvm question plz.
--- End quote ---
I have a multimeter,
I tried a test light on it of unknown wattage but it blew the bulb when I powered on, so I set the meter to DC 200
Pot in the 0 position reads 30
Pot in max position reads 45
am I right in thinking it should read 0?
John Rudd:
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!!
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