I have a White Knight Tumble dryer, and I'm sure the wiring is fairly standard. I am confused as I have just changed the heating element (which I have successfully done before), however, this time it does not work. I thought I had transferred the leads correctly, as I had done them one by one.

Upon closer inspection I am struggling to see how the wiring would work, even if I had got it right (assuming I haven't). There appears to be no live (switched) to the heating element, only neutrals. Surely it doesn't have a permanent live to the heating element switched by the neutral side, does it?

andrewcocke

If it is a 220-240 volt element, there shouldnt be a neatural hooked to it, you should have 120 volts on both sides. Placing your two meter leads on both terminals of the element while it is engergized should read 220-240 volts, if it does not, then you have a different problem.

Even if you hold one lead of your meter to ground, or neutural, and then test both sides of the element, you will most likley read 120 volts on both sides becuase its reading trough the element.

If you fail to read 240 volts when you read across the element while it is engergized we must suspect something else, some common problems would be a thermostat, high limit, etc. Unless we throw a bunch of parts at it, we will troubleshoot the dryer line for line.

Do you have a wiring diagram?

martinhough

Andrew,

Thanks for getting back to me so quickly. No, I don't have a wiring diagram. I don't think I've explained it quite well enough though.

The problem is that there appears to be no lead that is live, or even should be live. The live supply to the machine enters near to the connector block and into terminal 1. From here 2 leads go off down to the motor/timer. The neutral is on terminal 2. The heat element is a double ring, and has a bridge on one side. The other end has a red and black lead which is connected via a switch, which operates the half/full power of the heat element. This leaves the thermostat and the heat overload. There are no other leads running to this element. Therefore it would appear that the thermostat needs to be connected to the live input, and then onto the heat overload and then the red/black leads are neutral switching one element on/off. The problem with this is that I cannot see how the heat element can be switched as only one side of the element runs through the switch, if I was to connect the return side of the elelment up, surely it would stay on permanently and only be able to be switched on and off via the mains?

andrewcocke

Hello:

It sounds like you have something like this going on:
(dont take this for a diagram for your machine, it may not be exactly what you are dealing with, but might give you a frame of refrence:



As you can see, the timer switch control is defined by "Y", "R", and "Q" switches on the diagram, what these switched do and when they time out is illistrated on the table below.

Lets go with a simple timed tumble dry, set the timer and push the start switch, the start switch is pressed with time on the timer, switched Y,R, and Q close, the centrifugal switch in the moter closes, giving you a latching ciruit (hold the dryer on once you release the start button)

Voltage from L1 travels through R and into the high limit and tstat connected, then it will enter termal H3. This may be where you are seeing your "bridge".

From the looks of this diagram, the 1500W element is always on as long as there is voltage suplied at H3 and H2, the operator will have a switch that will determine whether the 3700W element will engergize at EX3. Currently, this drawing seems to illistrate both elements engergized.

So yes, one side of your element should always have 120 volts of electricity going to it. This 120 volts will be on potential L2. When the proper switches are closed (high limit/t-stat, etc) you will suply L1 potential of 120 volts to the other side of the element. This will give the element a 240 volt supply. If you were to take the other side of the element and ground it, or run it to a neutural, or ground it, it wont work, infact, it might short out, and throw sparks, really dont know, Ive never tried it.

Hope this helps.

This is a diagram to an old whirlpool machine. It might not be set up exactly how yours is, but it might give you some ideas anyway.

In any event, Id just hook up the new element as the old one came out. If the wires were changed around then the only way to really safley get it right would be to get a schematic for your machine, and go line for line. If you note the model and serial, and call the manfacturer, or visit a local appliance shop, you should be able to get a schematic.