Thetford toilet sensor

[royhedger]

Hello,
I have a Thetford toilet (not sure if model but it's 20 years old). It should have a full warning light which illuminates when the cassette is full but this does not appear to be working. I have changed the 2 x AA batteries and checked the electrical connections but am unsure how this sensor actually operates so don't know what else to check?
Is there a sensor in the cassette, or a float switch? The wires from the battery appear to terminate in a block near to the cassette but don't make any contact with it.

Any help appreciated,

Roy

 

[RogerL]

There's a float inside with a magnet which operates an external reed switch - the cassette needs cleaning internally, I do mine with Thetford Cassette Cleaner once a year.

 

[Woodentop]

If your waste container has a 'ring' around the slide, with the container empty remove the slide and put a piece of 2x2" or 3x2" timber across the runners and use it as a lever to rotate the 'ring' anticlockwise - there should be an arrow and mark on the case for guidance. It may be stiff if it has never been opened. Look inside the container at the blunt (rounded) end and you should see a translucent small float - like a small canister on a lever - in a moulded bracket on the end of the case. This float has a magnet inside it and when the cassette is full the float will hinge upwards pushed by the contents of the cassette. When near vertical the magnet should have enough power to operate the reed switch that is on top of the printed circuit board (PCB) at the back of the cassette housing. I suspect that either the float will be jammed (they commonly come adrift at one end and so cannot move) or it will be missing and have been flushed away.
If the float is present and can move easily then I suggest (with help) you offer a magnet up to the sensor in the housing and see if the light comes on. The reed switch is a small case about 3-4mm square and maybe 25mm long sitting horizontal at the top of the PCB. If the magnet test does not work then it may be that the soldering on the PCB has corroded and needs remaking or the reed switch has failed. The sensor PCB is quite easy to remove.

As a tip, if the top piece of the cassette was tight on removal, before reassembling lubricate the rubber seal (assuming it is intact) with a smear of extra virgin olive oil or (preferably) medical grade olive oil that you can buy from any Pharmacy for a couple of notes.

 

[otherclive]

As I am not visually or audibly challenged I gave up with trying to rely on the sensor. 😱

 

[Buckman]

As I am not visually or audibly challenged I gave up with trying to rely on the sensor. 😱

Easier to stick your finger in to check the depth. 😂😂 😂

 

[audiorob]

A good video appears here

thetford cassette toilet video - Bing video

www.bing.com

although the exact mechanism will depend on the model. If it is lost then replacements are available.
and this site should help you identify your particular model

CaravansPlus: Identifying Your Thetford Cassette Toilet Model

Not sure which model Thetford Cassette Toilet you have? This simple guide will show you how to easily identify your toilet to ensure you are buying the correct replacements. Article by Laura Smith - Caravans Plus

www.caravansplus.com.au

 

[royhedger]

Thanks guys. I shall have a look at the weekend and see what's up with it. At least I now know what to look for. 👍

 

[Mel]

In our van there is an audible warning. “The toilet needs emptying, Dear!” This initiates long before the light comes on. It is clear, loud and in a female voice.
Mel