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Thetford cassette electrical problem

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Hi all,


I’ve recently bought a 1996 Abi Award Superstar and I’ve had a few electrical problems with it. Most of them are sorted now but I’ve got a strange problem with the thetford cassette where when I press down on the flush button nothing happens at all but the car / van led on the power panel changes from green to red. What does this mean? The fuse for the cassette is ok and power is getting to the wiring but it doesn’t even try to flush. 


Thanks in advance, 



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You will probably find the pump is seized up. They are not difficult to replace, the last one I changed I used a cheap universal pump off eBay, like this one £7.09 delivered:


However, do check that it is actually the pump before you buy!

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Great thanks for those replies, got somewhere to start now. I’m also trying to get find this part from the primus heating / hot water system, it connects directly to the control panel for the primus system.  The control panel was dead when I got the caravan and then I found this part was burnt out. It’s mounted on the white part (pump?) in the photo. 




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The first photo shows relays and generally they have technical details in white on the clear case. 



Unless otherwise stated all posts are my personal opinion 

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Looking at it I guess it's a fairly simple board so I could just take it somewhere and get it replicated - probably be cheaper than finding a replacement part.

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I'm pretty sure that the white tubular unit is possibly an instantanious water heater, looking at the pcb which is just a couple of relays  and a resistor which would be way OTT for a simple water pump.


Also looking at the two black items under the jumble of blue wires, the one with the red button in the center looks like a re-settable over heat sensor, the other one looks like a thermostat.


Where do the two white pipes go to and from ?


Is there any info i.e.part numbers or name on the cover that fits over the electrics.


It looks like it has gone with a fair wallop so I would check to see if there is a direct short in the unit, difficult to know where to test without knowing exactly what the model is, before you try to source or repair the PCB.


Can you clean the soot off the writing on the PCB it may give a clue.


It's difficult to trace the wiring with them being tied up but the bus where most of the blue wires terminate look like they could be to heater elements.


It could be that there could be a couple of elements, a high wattage and a lower wattage giving three heat outputs controlled by the two relays, say relay 1 switching the low element, relay 2 switching the high element.


The three heats go like this, cooler  water setting, relay 1 switches the low element, medium heat, element 1 is switched off and element 2 switches on, hottest both elements switched on,.


It may have an internal pump also ?


In the heating control area, is there a  switch, or switchers  to select three heat ranges ?


What's the betting I'm totally wrong in guestimating what it is, still it keeps the grey  matter active. 🤭🤣😉


As Wispman says, there should be some printing somewhere on the relays to state what they are current ratings and so on, can you post these if they are on the relays.



Edited by Silversurf

Common sense isn't a gift, it's a punishment because you have to deal with everyone who doesn't have it.  :rolleyes:

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I forgot to mention last night that I noticed that you had pulled out the fuse holder on the fused spur, a good safety point, had the fuse blown, which would be expected looking at the PCB, if not it's possible the previous owner replaced the fuse, trying to solve the problem.

Common sense isn't a gift, it's a punishment because you have to deal with everyone who doesn't have it.  :rolleyes:

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