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Thetford 250


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Posted

My Thetford 250 toilet, the one with the press button flush, has decided to run flush water into the toilet bowl all on its own without any human influence!

Sometimes it will cease this activity by pressing the flush button rapidly but a few minutes later off it goes again. The risk here, of course, is that it will fill the bowl and flood the washroom floor.

I have levered off the self adhesive cover over the press button switch revealing the white plastic cover over the actuating plastic thingies which cover the printed circuit board, but inevitably can see nothing obviously wrong.

The main pump fuse has blown, replaced it, but no difference made to the phantom flusher.

Anyone have any ideas or do I call in an exorcist.

Tonio

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Posted

There is an electronic valve hidden deep in the loo, it is actually quite easy to get at and replace. When it happened to mine I rang Thetford support who told me what it was and gave me a phone number for parts and told me how to change it. The parts were about £12 iirr and came with comprehensive instructions. The easiest way is to ring thetford.

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I did ring Thetford and the technical guy said that it most likely needed a new pcb under the push button, or the wiring was corroded. The latter is most unlikely in a two year old caravan with the interior of the cassette compartment like new.

I have asked a NCC approved serviceman to look at the problem on Thursday.

Thanks, Bill, for your input.

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Posted

The symptoms on yours were identical to what happened to mine, but my van is now nearly 12 years old so probably a slightly different model. I am glad that Thetford were able to tell you where to look.

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I had this problem early this year and wrote about it here

http://www.touringandtenting.com/forums/index.php?/topic/48339-thetford-cassette-toilet-flush-button/page-1#entry543280

When I started I knew NOTHING about how to fix the Thetford -- by the end of two days I had learnt how to strip it down in half hour.

The fault seems similar to mine - under the blue push there is a little white button which presses down onto a switch which activates the pump.

I found that the switch has over heated and the copper spring contacts had become brittle and either were stuck open or closed..

Nothing you can do apart from replace it. The Thetford part number is 23792. [Cost £18 I think]That is the easy bit as to get it out you have to drain the tank and get out the wired which are connected to the little blue pump.

If like mine -- it will all be covered in black slime -- but persevere - and you will be rewarded .. keep washing every thing -- you will need to !!!

You do have to cut the wires and the join with the special clips and then heat shrink [hair drier] the cable covers over the joints for water proofing.

I didn't think I could do it - especially as you have to get your hand -arm in that 5" x 3" hole at the top where the button is. and do all the work from there.

You can get the Repair instructions -with pictures - from the Thetford web site Thetford-Europe.com.

Hope it helps

Maurice

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I did ring Thetford and the technical guy said that it most likely needed a new pcb under the push button, or the wiring was corroded. The latter is most unlikely in a two year old caravan with the interior of the cassette compartment like new.

I have asked a NCC approved serviceman to look at the problem on Thursday.

Thanks, Bill, for your input.

Thetford products have a warranty of 3 years so why not get the dealer to do the repair although that may be a problem as you have tried to fix it yourself. No harm in trying though.

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Posted

Thanks for all the input. It was definitely the printed circuit board. My NCC approved Mobile Workshop man, Matthew, fixed it yesterday. He told me that this is such a common problem that he carries spare pcb's on his van! Apparently because the pcb is located above the flush water tank in an area subject to condensation, warmer inside the van than outside, it gets condensation on it which leads to corrosion in the very small plug in connections to the pcb and hence it fails.

I didn't know that Thetford offered a three year warranty , probably a bit late now and I had to disconnect the wiring plug connection to stop the flush pump running dry and I had removed the peel off cover over the press button which probable invalidated any warranty.

Ho. Hum.

Tonio

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What did the PCB look like??

Mine didn't have one -- just a micro switch and connections which was activated when the blue button pressed on the white plunger then onto the micro switch all this contained in a black rubberised plastic cover fitted under the button bezel -- with two wires that hat to be cut and rejoined??

Is mine different in some way??

Maurice

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Posted

Maurice...isn't everything you have/had different to anyone elses?............Mine went last year and it was a five minute job to peel back the label, remove the small block and re-connect the wiring.....no sub-aqua required.

If anyone does have difficulty with under 3 year warranty claims, should your dealer not be an approved Thetford service agent then look on their website for your local one...I did just that and Ropers at Catterick sourced the spares f.o.c within a week.

geoff

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