Hi I think you must have a look at the drive board and connections. First unplug from mains then look inside control box looking for obvious first loose wire, burnt components or any signs of shorting. How old is the mill is it still under warranty. If it is call Chester on Monday they are helpful and even if it isn't they are still are helpful.

David

Disconnect the motor from the board, if its the KB or Chinese equivalent, the motor is usually wired to the A- & A+ terminals. Then connect a 100watt domestic light bulb to the terminals, then see if the rcd trips….

Another possibility is the thyristors, they are usually isolated tab devices and dont need an insulating washer. There have been cases where the insulation has broken down causing an earth leakage path. Otherwise the remainder of the electronics is not earthed as such.

The boards are repairable at a fraction of the cost of a replacement

John,sure….could you post up a picture of the board please?

Hi

Having read your posts of what is going on I wonder if the fault is with the controller board. You also say the speed display is unstable/flickering which I wouldn't necessarily associated with a fault on the control board, admittedly they are in close proximity with each other both physically and electrically. In your pictures there is an electronic transformer with a 12V AC output and I wonder if this is used to power the display circuitry. Looking at the picture of there appears to be 2 dirty/sooty marks where the white wires enter the supply, they could be shadows but they look more like definite marks which may indicate a problem with this unit. It may be worth disconnecting this unit from the mains supply and running the bulb test etc. again just to eliminate this unit prior to trying to repair or replace the control board.

Cheers

Martin W

I think Martin W is thinking along the right lines. I suggest disconnecting the live and neutral connections to the electronic transformer and see if the problem still occures. I can't read all of the lable on the electronic transformer so I can't tell if it is one designed for low voltage (12V) QA lighting. I assume that the PCB with the Atmel chip on is the tachometer and is probly supplied from the electronic transformer so it will probably stop working at all with the mains removed from the electronic transformer.

Les.

The electronic transformer is marked as supplying 12V AC 20W – 50W, if this is used as a circuit board supply as well then it would need rectifiers and smoothing circuits as well. Computer fans will not work if connected directly to this electronic transformer as they normally require to be supplied with 12V DC power and not AC. If this electronic transformer is solely used for a lamp circuit then there will have to be another psu circuit to supply the tachometer circuit see Les's post immediately preceding this. Good luck and lets hope it's something fairly simple and inexpensive.

Martin W

Edit for addition.

Does your mill have a low voltage light fitted? I have looked at the Chester site and can't see one on their current version of the 16V mill. A problem with a lot of these electronic transformers is that if they are run below a minimum load the output voltage can become unstable and fluctuate randomly between 0V – 12V.

Edited By Martin W on 27/11/2018 01:35:08

In respect of my two computer fans, I obtained a 12 volt transformer used for powering led lights and connected the fans to this and they work a treat. It doesn’t appear to be any different to the 12 volt transformer inside the mills control box, although I admit that I didn’t inspect it closely, just assumed as it was powering the mills low voltage light that it would power the fans, I shouldn’t have assumed but should have checked.

Dave W

Dave,
You must have been lucky that the fans worked as you must not have been checking the polarity when connecting them as you first connected them to an AC supply.

Les.