My caravan has a Thetford C-200 CS D3 toilet cassette which has a small light which illuminates when the toilet cassette is about 90% full, it has stopped working.
A brief inspection of the system suggests the "full" sensor is a small black plastic component at the top left front of the cassette compartment when viewed from the outside and looking into the caravan.
I'm not sure what this component is but I have it in mind that some polymers are transmissive to infrared (or is it UV?) and I wonder if this is how it senses level? Alternatively it could be some sort of clever proximity sensor which responds to liquids but not solids? Or it could be something else entirely and I have no idea what I'm talking about! :)
So I suppose my question is:
Does anyone know how this thing works?
Possum3 said
02:10 PM Jan 11, 2023
Mike it is most probably the float stuck in down position in Thetford tank - happens when paper floats over float arm (hardens like paper mache') usually when sloshing cleaning water when rinsing. Open top and free paper/crap from float, spray with olive oil replace top and replace cassette.
Alternatively float come off it's mount - remove top replace float, etc.
-- Edited by Possum3 on Wednesday 11th of January 2023 02:12:15 PM
Mike Harding said
02:13 PM Jan 11, 2023
Hi Possum
Thanks for your reply.
There is no float in the cassette, it's just a plastic box with inlet, outlet and pressure relief valve.
As far as I can see level sensing is done electronically, remotely and externally.
Hylife said
02:51 PM Jan 11, 2023
Yes, there definitely IS a float in all Thetford toilet cassettes.
It is not uncommon for it to be dislodged and lost down the dump point.
I suspect the external sensor is a Hall Effect and the internal float contains a magnet which, perhaps, has wandered off to have a life of its own - I have no desire to pursue it :)
Oh well, I guess we'll have to go low tech and simple look into the tank to assess how full it is.
Whenarewethere said
04:14 PM Jan 11, 2023
With a mirror!
Bas + Eve said
04:34 PM Jan 11, 2023
There is a fuse behind where the cassette sits, 3 or 5 amp from memory. Also there is a square relay mounted in same vicinity. Its a common relay. I have changed both over 11yrs. Easy job. If that fails you can just replace your cassette as the problem may be in the float switch. You can repair them but for $180 (on special) thats what I do. Its all dependent on time, mess and dollars.
Possum3 said
04:38 PM Jan 11, 2023
Mike the parts are relatively cheap from Thetford direct (Britain) great delivery - Caravan Plus in Qld also have them if needed (not as cheap).
Rarely does the float go down the chute they normally just jam - Open top of cassette (less than one minute) www.bing.com/videos/search
Long Weekend said
05:29 PM Jan 11, 2023
Mike,
Been there, done that! Hope you didn't get an overflow like I did! (Luckily, I keep a packet of disposable gloves and disinfectant in the van.)
Like you I found the float arm missing, replaced that with considerable difficulty. Still didn't work. Then found that the light itself had burned out, replaced that with a nice large red one from Jaycar. Still didn't work. Checked the fuse - the previous owner had put a 15-Amp one in, obviously a bit of an overkill as probably would only require something like a 5-Amp at the most, but it indicated that the previous owner also had a problem. Fuse OK but still doesn't work.
Checked the magnetic relay switch with a hand held magnet - the light worked. But the newly installed freely moving float arm inside still didn't activate the light. Another overflow.
Then like Bas & Eve, I also bought a new cassette after I damaged the old one trying to open the top up so that I could access the inside better.
Now as we only use the cassette at night and use the CP's facilities during the day I simply empty the cassette every two days without fail.
While typing this I pondered - I wonder if the magnetic relay switch could have been knocked out of alignment and thus not being close enough to the cassette side for the magnet to exert sufficient pull on the reed?
I'll check that before our next trip. In the meantime, has anyone else anything that I could try?
Murray
BAZZA44 said
06:27 PM Jan 11, 2023
Why bother with the float, I just look through the opening after flushing to see how full it is. Never had a spill.
Barry
Aus-Kiwi said
07:32 PM Jan 11, 2023
Try filling with a few ice cubes, 3/4 full of water & detergent . Go for a drive around the block ? Fibre they say keeps things flowing !!
thomas01 said
07:41 PM Jan 11, 2023
I agree with BAZZA44.
It's a bit like looking for your phone so that you can turn the lights on via an app. Then you realise the light switch is closer.
Another useless gadget that some people MUST use, just because they can. Wouldn't want to wear our eyes out now, would we.
Robert.
Cupie said
11:42 PM Jan 11, 2023
BAZZA44 wrote:
Why bother with the float, I just look through the opening after flushing to see how full it is. Never had a spill.
Barry
Me too
Many moons ago my 'cassette full' light stopped working. The reason was that the 'pendulum' with the magnet had jumped over the wrong side of a locating ridge & when it was forced up it was nowhere near the relay. Maybe I shook it too vigorously when cleaning.
I no longer rely on the light, just keeping an eye on the level & emptying it every 3rd day or when moving to a new location.
Whenarewethere said
05:44 AM Jan 12, 2023
thomas01 wrote:
I agree with BAZZA44.
It's a bit like looking for your phone so that you can turn the lights on via an app. Then you realise the light switch is closer.
Another useless gadget that some people MUST use, just because they can. Wouldn't want to wear our eyes out now, would we.
Robert.
A bit like solaR meter gadgets. Initially one is constantly looking at the input & output apps.
After some months you know that the batteries will need charging after X number of days depending on input, output & capacity.
No different to the input of sausage rolls & then your bum's output.
After X number of days factoring safety margin the smart ones empty the bucket!
My caravan has a Thetford C-200 CS D3 toilet cassette which has a small light which illuminates when the toilet cassette is about 90% full, it has stopped working.
A brief inspection of the system suggests the "full" sensor is a small black plastic component at the top left front of the cassette compartment when viewed from the outside and looking into the caravan.
I'm not sure what this component is but I have it in mind that some polymers are transmissive to infrared (or is it UV?) and I wonder if this is how it senses level? Alternatively it could be some sort of clever proximity sensor which responds to liquids but not solids? Or it could be something else entirely and I have no idea what I'm talking about! :)
So I suppose my question is:
Does anyone know how this thing works?
Mike it is most probably the float stuck in down position in Thetford tank - happens when paper floats over float arm (hardens like paper mache') usually when sloshing cleaning water when rinsing. Open top and free paper/crap from float, spray with olive oil replace top and replace cassette.
Alternatively float come off it's mount - remove top replace float, etc.
-- Edited by Possum3 on Wednesday 11th of January 2023 02:12:15 PM
Hi Possum
Thanks for your reply.
There is no float in the cassette, it's just a plastic box with inlet, outlet and pressure relief valve.
As far as I can see level sensing is done electronically, remotely and externally.
It is not uncommon for it to be dislodged and lost down the dump point.
Go Here to see what it looks like.
www.caravansplus.com.au/23726-float-arm-suit-thetford-c200-toilets-p-14629.html
Yes, thank you both now I see the light! :)
I suspect the external sensor is a Hall Effect and the internal float contains a magnet which, perhaps, has wandered off to have a life of its own - I have no desire to pursue it :)
Oh well, I guess we'll have to go low tech and simple look into the tank to assess how full it is.
With a mirror!
There is a fuse behind where the cassette sits, 3 or 5 amp from memory. Also there is a square relay mounted in same vicinity. Its a common relay. I have changed both over 11yrs. Easy job. If that fails you can just replace your cassette as the problem may be in the float switch. You can repair them but for $180 (on special) thats what I do. Its all dependent on time, mess and dollars.
Rarely does the float go down the chute they normally just jam - Open top of cassette (less than one minute) www.bing.com/videos/search
Been there, done that! Hope you didn't get an overflow like I did! (Luckily, I keep a packet of disposable gloves and disinfectant in the van.)
Like you I found the float arm missing, replaced that with considerable difficulty. Still didn't work. Then found that the light itself had burned out, replaced that with a nice large red one from Jaycar. Still didn't work. Checked the fuse - the previous owner had put a 15-Amp one in, obviously a bit of an overkill as probably would only require something like a 5-Amp at the most, but it indicated that the previous owner also had a problem. Fuse OK but still doesn't work.
Checked the magnetic relay switch with a hand held magnet - the light worked. But the newly installed freely moving float arm inside still didn't activate the light. Another overflow.
Then like Bas & Eve, I also bought a new cassette after I damaged the old one trying to open the top up so that I could access the inside better.
Now as we only use the cassette at night and use the CP's facilities during the day I simply empty the cassette every two days without fail.
While typing this I pondered - I wonder if the magnetic relay switch could have been knocked out of alignment and thus not being close enough to the cassette side for the magnet to exert sufficient pull on the reed?
I'll check that before our next trip. In the meantime, has anyone else anything that I could try?
Murray
Barry
It's a bit like looking for your phone so that you can turn the lights on via an app. Then you realise the light switch is closer.
Another useless gadget that some people MUST use, just because they can. Wouldn't want to wear our eyes out now, would we.
Robert.
Me too
Many moons ago my 'cassette full' light stopped working. The reason was that the 'pendulum' with the magnet had jumped over the wrong side of a locating ridge & when it was forced up it was nowhere near the relay. Maybe I shook it too vigorously when cleaning.
I no longer rely on the light, just keeping an eye on the level & emptying it every 3rd day or when moving to a new location.
A bit like solaR meter gadgets. Initially one is constantly looking at the input & output apps.
After some months you know that the batteries will need charging after X number of days depending on input, output & capacity.
No different to the input of sausage rolls & then your bum's output.
After X number of days factoring safety margin the smart ones empty the bucket!