A potters wheel need to repair - Newbie help with electrics.

MisterBill2

Joined Jan 23, 2018
18,167
I suggest carefully and gently opening that yellow box and seeing what is inside. If the motor is a DC motor and only runs on DC, then some place there must be a rectifier system of some kind. Be very careful to note what is connected to each of the wires that go to that yellow box, because they are not interchangable. Probably the box contents are both the rectifier and the speed controller, which may be a variable resistor.
 

Thread Starter

threlfaw

Joined Nov 2, 2018
7
Sorry for the delay guys, had issues with my phone, so was unable to take photos.
Anyway, sorted that now so have uploaded more of the yellow thing!IMG_0021.JPG IMG_0022.JPG IMG_0023.JPG IMG_0024.JPG IMG_0026.JPG
 

MisterBill2

Joined Jan 23, 2018
18,167
OK, good pictures, although none of them show the connections to that big round item driven by the smaller gear. But now we know that it is some real electronics controlling the motor, with a mechanical switch that is operated as the control reaches maximum rotation, or possibly minimum, depending on what position the device is in as we see it.. What remains unknown is the connections to that 8 pin connector, except that one of them is the green-wire safety ground. Then two connections are for incoming power and at least two are for the motor, with what we see probably hard to guess which.
BUT no parts look burned and so it may be that the whole thing works well as it is.
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
The speed is governed by the foot pedal which intern pushes a level attached to the Yellow Box, so i guess that controls the motor speed.
What is on the other end of the arm that is operated by the oscillating gear ?
It is possible the speed control is by mechanical means between motor and final output shaft
The board just appears to be DC supply for the motor.
The external wiring comes in through the octal socket and the on/off P.B. most likely picks up the cube relay.
I don't see any electrical speed control components?
What does the arm operate into? It obviously works in a oscillating motion.
Is there any detail of the rotary table itself.
Max.
 
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MaxHeadRoom

Joined Jul 18, 2013
28,617
I believe I found it, the manuf. of the unit are heavy into Variac's so it appears they make one with a Variac control, the arm moves/rotates the Variac, that would make sense of the partial rotation of the arm.
Max.
 
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Alec_t

Joined Sep 17, 2013
14,280
I'm guessing the black gear moves the wiper of a big variac housed in the grey cyclinder. Seems to be a tapped variac, with a tap-selector rotary switch. Presumably a pedal moves the rod which moves the lever to adjust the variac?
 

MisterBill2

Joined Jan 23, 2018
18,167
OK, so the mystery cylinder encloses a variac transformer, and the sector and pinion rotate the variac to set the output DC voltage to power the DC drive motor. The microswitch turns off the DC and short circuits the motor to provide a quick stop when the pedal is released. So the external switch is to control the AC mains supply input.
My guess is that if anything has failed it is the microswitch connection to quick-stop the motor. So my suggestion is to power it up with a 60 watt incandescent light bulb in series with the line connection to limit the current in case there is a fault. Good Luck!!
 
#1 check the motor brushes. Motor brushes do wear out and need to be replaced periodically. They need to be at least 1/4" (6mm) " long.
I do not see a fuse anywhere but the French rely on the main control panel breaker. Just kidding. What I imagine is this:
The pedal controls the relay on the rectifier-PCB. The relay switches the motor on-off. There is a limit switch in-between which switches the running direction of the motor. With power on, press the pedal and see if the relay is clicking. If not, there is no power to the PCB or the relay is bad. It could be the ON/OFF switch. If is clicking, the the limit switch could be bad or broken connection between the PCB and motor. let us know.
 

MisterBill2

Joined Jan 23, 2018
18,167
#1 check the motor brushes. Motor brushes do wear out and need to be replaced periodically. They need to be at least 1/4" (6mm) " long.
I do not see a fuse anywhere but the French rely on the main control panel breaker. Just kidding. What I imagine is this:
The pedal controls the relay on the rectifier-PCB. The relay switches the motor on-off. There is a limit switch in-between which switches the running direction of the motor. With power on, press the pedal and see if the relay is clicking. If not, there is no power to the PCB or the relay is bad. It could be the ON/OFF switch. If is clicking, the the limit switch could be bad or broken connection between the PCB and motor. let us know.
I would think that the relay disconnects the motor when the speed pedal is released, because there is seldom, if ever, a need to reverse a potter's wheel. AND none of the pictures showed any external limit switch.
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
It would be my guess the external ON/OFF push button picks up the relay to arm the Variac circuit and from there the rpm is controlled by the pedal.
There is also a micro switch that appears to be activated by the gear sector.
The fact the switch appears to have been cut off maybe the reason for the original non-use, the replacements are quite pricey but the Co. also advises they can repair them at a lower cost.
If this were reverse-engineered it should be possible to come up with an equivalent replacement/circuit.
Max.
 

MisterBill2

Joined Jan 23, 2018
18,167
Going back to the start of the thread, what seems to be missing is a connection from the blue mains supply to the yellow box. This is why it does not work at all, although there may be other problems as well. So I suggest that you attempt to contact the manufacturer for some additional information. My guess, which is ONLY A GUESS, is that it may connect to that blue wire that is connected with the purple wire in that splice block, shown in one of the pictures. What is the thing sown with the two black wires entering through a strain relief in one of the pictures?
It certainly does appear that it has been worked on by an individual devoid of any electrical insight. And it may also be that there is some other unknown problem that prompted them to attack.
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
I would guess the reason it is not presently working is due to the severed ON/OFF SW!
The manuf. is still in business so they may come up with a schematic.
As unless the skills are there to reverse-engineer it, this would be the quicker way.
info@rilton.co.uk
Max.
 
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MisterBill2

Joined Jan 23, 2018
18,167
I would guess the reason it is not presently working is due to the severed ON/OFF SW!
The manuf. is still in business so they may come up with a schematic.
As unless the skills are there to reverse-engineer it, this would be the quicker way.
info@rilton.co.uk
Max.
Max, consider that the wires attached to the switch contacts are yellow, while those soldered to the indicator are brown. Next consider that the only wire that is even slightly yellow is the yellow with green striped ground connection. So it is not likely that the switch, an industrial type device, was part of the original package. What does appear to be missing, both from the circuit drawing and by observation of the photos, is a connection from then blue wire in the mains connection to anything. I am thinking that a complete power connection is needed for almost anything to happen.
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
So it is not likely that the switch, an industrial type device, was part of the original package.
I remember assisting someone on another forum about 10yrs ago that was trying to locate the identical part in order to repair a potters wheel, who needed the source of a replacement.
Not likely a coincidence!
Max.
 
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MaxHeadRoom

Joined Jul 18, 2013
28,617
Not sure if @threlfaw is still interested, but I had one of my UK contacts put some feelers out and apparently Rilton Electronics was disolved a few years ago.
So the option of an original schematic from them is probably out of the question.
And BTW it also turns out that Rilton were the UK stocking distributor of the P.B. Breaker switches shown in the OP's picture!
Max.
 
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MisterBill2

Joined Jan 23, 2018
18,167
Worst case effort would be to trace out the circuit inside the yellow box. At that point it would be simple to understand where each connection point should be connected, given that the only output is to a variable speed DC brush type motor, and also given that the only controls are mains power and rotation speed, which appears to be rotating the variac transformer, with the switch doing something at either zero rotation or max rotation. The whole system can't be that complicated, can it????. Probably, with an adequate photo of the circuit board, we could trace the circuit completely. Then only the external connections would need analysis. Of course, I have obtained circuits for quite a few things from sources not related to the manufacturer. So there are a number of possibilities and options available.
 
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