# Faulty CBE tank sensors (always 100%)- Hobby Sphinx?



## dct67 (Sep 23, 2007)

Ahh, the joys of buying privately - I didn't think to question the 100% readings on the waste and fresh water tanks. In fact the vendor specifically mentioned the waste tank needed emptying.

Anyway, once back home, I opened the waste outlet - and nothing came out! Initially I figured a blockage, but after filling the waste tank using the basin and sink, it was clear that the display was lying! Both the fresh and waste tanks still firmly showing full.

Anyway, after much googling, I believe that the Sphinx has capacitative tank sensors from CBE - perhaps model "SPE". I thought perhaps it was a control panel fault, but it looks like both the sensors are sending 2.5V back to the panel - which is the voltage for 100% full.

Would anyone have any idea how to access the tank sensors in a Hobby Sphinx? There appear to be 2 circular "cutouts" in the floor of the Hobby but no handles or suggestion how these should be accessed.

Also, has anyone had problems with these sensors in the past? Are the repairable or should I be looking for a replacement?

Thanks!

David


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## teemyob (Nov 22, 2005)

*Sesnors*

Hello David,

I have no idea how you access the sensors.

But as you asked, we had an issue with our waste one. When I removed the large round red access cap from under the floor hatch. I found the sensor had become clogged with gunge. Very quickly solved by way of wiping the prongs.

TM


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## bozzer (Jul 22, 2009)

Not a Hobby but we have sorted our Chausson fresh water today.

Our waste water shows the capacity available and when empty shows 98l but as you fill the no goes down showing what you have left.

The fresh water shows what is in the tank. On the top of our tank is electric cable going to the sensors. On the top of the sensor is a very small screw which you can calibrate the reading. However our problem was a poor connection along this cable where there was male/female connector and this hadn't been pushed together. Snap connector together and we are getting correct readings previously we always had 128l in the tank even when empty!!!

May be some help but not specific for your Mhome

Jan


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## wooly (Oct 3, 2007)

Hi, CAK Tanks sell the CBE sensors, beware there are different length ones and you cant shorten them. It is also posssible that the waste tank may have different sensors for the waste tank to the fresh tank. Most CBE Panels use button sensors in the waste which read at 75, 90 and 100% full.
Michael


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## dct67 (Sep 23, 2007)

Thanks for the suggestions.

I had another fiddle with the disc shaped cutouts in the floor of the motorhome, but couldn't budge them, so can't even get to the sensors to have a gander.

I'm quite keen to have a look and see what a capacitative sensor looks like - in theory they don't even need to be mounted in the tank (at least the ones sold in the US are mounted on the outside of the tank).

Thanks again

David


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## sheppy (Nov 10, 2010)

hi i am new to this motorhome but the grey waste level worked once and on second trip shows 0% when full , is there a way to reset on main console (autotrail arapho) :?


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## Traveller_HA5_3DOM (May 9, 2005)

dct67 said:


> Thanks for the suggestions.
> 
> I had another fiddle with the disc shaped cutouts in the floor of the motorhome, but couldn't budge them, so can't even get to the sensors to have a gander.
> 
> ...


They look like a thin immersion heater element. I changed one on our old Castaway and had to drop the waste tank to get to it. It was scaled up when I got it out but cleaning it did not revive it. As said CAK sell them and you can sometimes squeeze a slightly longer one in. You can also use a shorter one and that will give you and increased reserve from the design spec.


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