candy rapido e20 (draining fault but washer drains fine)

[antwanuk2012]

hi guys as per the title i have a candy Rapido (wifi) that's just started randomly gave an e20 fault.

after the usual google search i was directed to a drainage issue.   i attached the drain hose to a bucket and run the washer again to see it emptied perfectly the pump is clean the pipes are free of blockage including the drain from the drum to the pump.

at no point dose the drum turn at all though so im thinking the controller is having some sort of sense issue maybe its not aware the drainage pump is working so its not moving on in the program. 

the issue is the pump only has two wires so it cant be the pumps fault it has to be something at the controller end maybe current sense? 

i know my way around electronics as I do audio and lighting as a job and im used to repairing equipment iv got a full set up for testing and repairs but rather then spending hours messing with a conformably coated  controller i have no experience with  i hoping one of you far more experienced guys can help me out.

Thanks in advance 

Ant

ps it would get the wife of my back if i can fix it cheers guys 

[Whitegoodshelp (Andy)]

Hi there. When you say that the drum does not turn at all, was this when you were testing it with the drain hose in a bucket, or before? It's just that placing a drain hose in a bucket will just cause the water to siphon straight out. A washing machine can't function with the drain hose in a bucket, although if the bucket is raised about 3 feet off of the floor it would be okay.

If the washing machine is indicating a drainage issue but the water is pumping away perfectly okay then the error is not referring to drainage issue, or possibly there is a pressure system fault that is stopping the washing machine software from knowing when water is in the machine and when it is not in the machine. But if the symptoms are that the washing machine drum never turns that's a totally different fault altogether.

[antwanuk2012]

thanks for the reply sorry i didn't see this sooner i didn't et any notification. the drainage pipe runs up from the bottom and up to the top to act as trap and anti siphon then in to large mixing bucket no water moves until you start the program you can see the water pulsing as the pump surges but at no point dose the drum move which is why i think the error is wrong. it drains then fills a little then drains some more but i assume the drum should spin during draining. i get resistance across various pins various phases so i don't think its a brush issue either. You mentioned pressure issue the pump has no sensors its self and from what i can see the drum simply drains straight into the pump and the raised drainage pipe at the rear hold the water in. maybe there is a sensor in the drum to detect water ill have to have a look if its in the drum it must be near the heating element id think. 

I work on audio equipment as a hobby/side job so i know my way around electronics but obviously appliances are a different kettle of fish  thanks for the help 

[antwanuk2012]

hi all just to let you know i had a look at the pressure sensor and it was putting out some strange readings on my scope its failed so £12 part is on its way ill update you after replacing it but after blowing into it pretty hard the washer started to work perfectly fine so its probably a failed diaphragm in the unit

[Whitegoodshelp (Andy)]

Thanks for updates. Modern pressure switches should give varying readings as the magnet rises. I believe they work by monitoring resistance readings as the magnet rises although I've not seen any actual explanation of how they work.

The previous design of pressure switches were just spring-loaded switches that are either on or off. Historically pressure switches have always been extremely reliable parts and I hardly ever remember having to change one.

The most common cause of the washing machine thinking there is water in the drum when there isn't is blocked pressure system. I would also check for this.

• Common faults on washing machine pressure system
• Clearing a blocked pressure system

[MelS]

Modern pressure sensors have a coil of wire, wired to a capacitor, the magnet moves into the coil which changes its inductance and the frequency they will oscillate at. Some have additional circuitry to make it oscillate, and others would have that on the control board. I would expect them to be pretty reliable, so most likely a blockage somewhere caused by gunk, or limescale.

Here's a video that explains it better that I can 

youtu.be/O-0KGbd91_I

 

  

Edited October 25 by MelS

[Whitegoodshelp (Andy)]

Thanks for that MelS. As far as I can see the modern electronic pressure switches work just how I envisaged. That is there is an electric coil and a magnet. The air pressure created by the water causes the magnet to slowly rise inside the coil. The electronics can then monitor the output or resistance in the coil and be able to tell how far up the magnet has been pushed and therefore how much air pressure (and of course water level) is present.

I would still expect them to be a very reliable part, but quite possibly nowhere near as reliable as the pressure switch is that they replaced. As I said before, I can hardly ever remember replacing a pressure switch which in a washing machine in well over thirty years repairing them. They are exceptionally reliable. These modern ones now have small circuit boards, with small capacitors and chips inside which are all prone to potential failure.

I would still expect that the most likely cause of any problem with water levels is likely to be grease crime and gunge blocking the pressure chamber. This would prevent air from getting into the pressure switch, or conversely with some types of less-solid blockages, trap air inside the pressure switch.