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Duffy

Thetford C250 Electric Toilet Flush Problem

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Hi

I have a Swift 495 Freestyle 2009 and on our last outing the Thetford C250 toilet will not flush I checked the 3 amp fuse which had blown replaced that, it still would not work. The toilet warning light to indicate full, this is ok. I suspect the pump may have failed could any tell me how i can access the pump to check it over and possibly replace it.

Many thanks in advance for any help.

Best regards

John Duffy

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Remove the pump from the waste housing area and turn the pump impeller using a long thin screwdriver, once you have it turning all will be well again. .. (Probably)..

 

Works for me at the beginning of every summer :o

 

Failing that. . Check the switch board connections under the switch. The circuit board uses an edge connector that is prone to corrosion.

Edited by dreadly

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Hi

Many thanks for the info from Dreadly did as he said pump will still not work Thetford C250.

Removed plastic cover to locate PCB board checked to see if supply was coming to the PCB, meter read 12. 95 volts so that was ok but when i operated the switch there is no voltage to the pump. I thought that it may be the PCB board that was faulty so and went and purchased a new oneat £17. 99 fitted it still the pump will not work. Connected a direct 12 volt supply to the pump and it works ok.

The terminals on the PCB and connector look ok.

One thing that puzzles me is that the input supply reads 12. 95 volts as it should but when i press the switch to operate the pump the voltage reading on the same terminals drops to 3. 55 volts, so i don't understand whats going off. I am at a loss at what to do next.

Any further help would be much appreciated.

Many thanks in advance for any help.

John Duffy

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That suggests there is a high resistance connection (poor connection) on the supply side to the PCB.

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There is an electrical join that supplies power to the unit just inside the waste carrier door to the bottom right, keep pulling the cable until it comes to the plastic join then make sure this part is not heavily corroded.

Also recommend cleaning the fuse contacts behind the waste carrier.

 

This was apparently the worst and most unreliable toilet ever made BTW. ..

 

Coat anything electrical on this toilet in copious quantities of Contralube gel from Maplins to prevent further corrosion. ..

 

Just to add. .. Where are you in the country? If you are down south. . I could possibly help.

Edited by dreadly

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These C250's are a pain (that’s as diplomatic as I can get LOL), especially the older ones (various mods. have been incorporated in an attempt to improve what is basically a very flawed design).

Poor design ensures frequent electrical faults due to damp & low quality parts but finding the fault is not easy as you are finding out. 'Ich' is probably correct in his suggestion.

You've mentioned that the pump works if wired direct & this is what I intend doing (via a press button switch) the next time mine plays-up, after all, it's not gimmicks we want it's a pump that works reliably ALL the time.

Perhaps I've been spoilt by previous models that were not only better built but fault (& gimmick!)-free, hence totally reliable?

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I have been fighting with my C250 for a month all bits replaced and still not working, loada rubbish.

 

geoff

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There's another connector and pcb at the back of the waste tank held behind another white plastic cover (on the vertical face). Forgotten what it's called but this is another thing that can go wrong.

Hope that helps

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There's another connector and pcb at the back of the waste tank held behind another white plastic cover (on the vertical face). Forgotten what it's called but this is another thing that can go wrong.

Hope that helps

That is just a reed switch that tells you when the toilet is full, very crude and badly designed as it is it should not stop the pump working.

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Hi

Many thanks for all the replies to my problem of my toilet not flushing. I have now solved the problem and it works fine.

As many of the answers said and on other forums the problem was the 3amp fuse holder at the back of the waste tank it must have been badly corroded. I by passed this fuse and connected a piece of short wire directly into the contacts at the back of the fuse holder i know that's a bit dodgy and hey presto the pump worked. Cut the wires off went and bought a new fuse holder and connectors as someone suggested put it in a plastic bag taped it up to keep it dry and put it right at the back behind the waste tank.

Many thanks once again for all your help.

John Duffy

 

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Hi all - As there were 3 topics, and duffy has found the problem, I have now merged all 3 into one topic and hope it all makes sense.

 

Duffy's post No. 10 makes it all clear.

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That is just a reed switch that tells you when the toilet is full, very crude and badly designed as it is it should not stop the pump working.

Stopped mine working, until they realised it was also the circuit board as well!

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Stopped mine working, until they realised it was also the circuit board as well!

I believe it is a cut-off reed switch - i. e. permanently open until the waste reaches a certain height, then it will close the reed switch and cut-off the flush mechanism by activating a transistor switch on the main circuit board.

This can be corrected by simply removing the small circuit board behind the storage tank.

The connection to the circuit board also suffers from heavy corrosion and when you remove the connector the solder contact tracks on the board can come off the circuit board as they are stuck to the connector.

The reason I say that the circuit board 'should' not stop the toilet working is that most of the time these circuits fail 'open circuit', not closed. So for this component to fail like this it should be very rare and we are trying to work out common causes in the first instance. . In fairness it is more likely that the main board fails or the damn fuse.

 

WHO in there right mind would put a fuse in this location that is not protected from corrosion? It really makes no sense. Also who would put a circuit at the top of the holding tank that is also completely open to the holding tank itself and any associated moisture and use an edge connector with tin contacts??? - Absolute stupidity. These people need to employ better designers IMHO. Are Thetford on this board. .. :ph34r:

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I have been fighting with my C250 for a month all bits replaced and still not working, loada rubbish.

 

geoff

 

You got that in 1!

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Hi, I appear to have the no flush and no full warning, but fuse not blown. Was about to order a new control panel but should I be trying other things first? Other than possibly spraying everything with anti corrosion spray?

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Hi, I appear to have the no flush and no full warning, but fuse not blown. Was about to order a new control panel but should I be trying other things first? Other than possibly spraying everything with anti corrosion spray?

Try the switch on top of the toilet. Its normally that. To get to it the sticker on the top of the toilet needs to be lifted (almost sacrificial. ...) and then you can get to the switch there

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Rub the blades of the fuse with emery paper first and if that doesn't work replace it. Common problem - fails internally, to give a high resistance.

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For the record, the tank full light (LED) is fed by batteries in a pack container just inside the outer door. The activator inside the tank is simply a magnet on the end of the arm of a float that moves towards the outer case and is sensed by the external circuit when the tank is full - whether that is a reed switch or a Hall effect sensor I know not. Said float often gets bunged up by paper that is not dissolved and jams it.

 

Whilst we are talking of toilets, has anyone on here cleaned their waste holding tank by disassembly and replaced the lip seal? I did mine last weekend - it took over two hours to clean the trap system alone! Mind you that was largely due to limescale build up after use in France where most water is VERY hard. Having chipped off as much as I could I filled it with waste tank cleaner in a strong warm water solution and left it as advised for 16 hours. Boy what a difference that made!

 

If anyone needs more info, www. leisurespares. co. uk have exploded diagrams of Thetford toilets and Dometic fridges on their web site which helps enormously and also makes sure you order the right part number.

Edited by Woodentop
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For the record, the tank full light (LED) is fed by batteries in a pack container just inside the outer door. The activator inside the tank is simply a magnet on the end of the arm of a float that moves towards the outer case and is sensed by the external circuit when the tank is full - whether that is a reed switch or a Hall effect sensor I know not. Said float often gets bunged up by paper that is not dissolved and jams it.

 

Whilst we are talking of toilets, has anyone on here cleaned their waste holding tank by disassembly and replaced the lip seal? I did mine last weekend - it took over two hours to clean the trap system alone! Mind you that was largely due to limescale build up after use in France where most water is VERY hard. Having chipped off as much as I could I filled it with waste tank cleaner in a strong warm water solution and left it as advised for 16 hours. Boy what a difference that made!

 

If anyone needs more info, www. leisurespares. co. uk have exploded diagrams of Thetford toilets and Dometic fridges on their web site which helps enormously and also makes sure you order the right part number.

The easy way to clean these up is to fill it with a couple of litres of white vinager and put it in your car boot for a couple of days and drive. .. It will come up great. Then do the same with a little cleaning fluid instead of vinager.

Tie it in a sealed bin bag and dont let it move around though.

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Hi

Had an issue with my toilet not flushing either. To cut a long story short the fault was down to the 3A fuse which although showed Ok with a continuity tester was infact a resistor when pulling current through it and hence the pump not working.

However, I did pull the pump out before I found this and attached to the top of the pump is a 6" piece of pipe with a "plastic assembly" on the end. Now my question is, is this just shoved back up inside the toilet or have I pulled something out that I shouldn't have?? I just noticed some clips on it and thought if this falls over in use I will be leaking flush water out.

 

Any help appreciated.

 

Neil

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Hi

Had an issue with my toilet not flushing either. To cut a long story short the fault was down to the 3A fuse which although showed Ok with a continuity tester was infact a resistor when pulling current through it and hence the pump not working.

However, I did pull the pump out before I found this and attached to the top of the pump is a 6" piece of pipe with a "plastic assembly" on the end. Now my question is, is this just shoved back up inside the toilet or have I pulled something out that I shouldn't have?? I just noticed some clips on it and thought if this falls over in use I will be leaking flush water out.

 

Any help appreciated.

 

Neil

The pipe attached to the top of the pump is the water pickup pipe, these all feed in from the bottom of the unit. These pumps can actually be replaced with any equivalent sealed pump for around a fiver, the £30 that thetford charge is crazy and unjustified IMHO.

The fuse will and does rot due to the poor position, as does the fuse holder and the lever sensor circuit board. These should all receive a generous coating of Contralube to prevent future corrosion.

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Thetford C250 Electrical Flush problem and Tank Full intermittent light.

 

Got a Bailey Mk1 Unicorn Valencia 2011 that developed a no flush when pressing the button.

Also intermittent cassette full warning light.

 

The two problems are separate, the No Flush fault came down to a corroded 7 amp fuse holder inside the cassette housing also corroded the fuse.

The location of the the fuse holder is not the best place to be as wet condition contribute towards the corrosion.

 

So I have replaced with a weather proof fuse holder and mounted it up higher just behind the Reed Switch bracket.

 

This comes on to the 2nd intermittent tank full RED warning light on the REED circuit board, the bracket has become loose and moves back and fought that holds the REED board, also check the board for corrosion on the edge wire connector.

 

The cheap option is to put a small piece of sponge behind the bracket to the back wall of the cassette housing to act as a shock absorber when you insert the the tank cassette.

I hope this helps.

Mike

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Yes Mike. .matches my experience too. ..help if you miss out the sponge as it absorbs/holds water,,,put the fuse assembly in a plastic food bag. ..

 

geoff

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Get yourself some Contralube grease and coat all of exposed wires, connectors and circuit boards in it. No more rot, no more shorts. Great stuff IMHO.

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Thanks to this post i fixed my C250. Fuse was corroded so i replaced that then checked for 12v from connectors tucked away in small hole right side near door and then at fuse and across fuse, all ok then removed sticker on flush button and removed PCB only to see it corroded and circuit tracks blackened. Replaced PCB and used silicone grease and covered all connections and PCB boards hopefully years of trouble free use.

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