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Dales-Electronic
Dales-Electronic, Home Appliance Technician
Category: Appliance
Satisfied Customers: 1466
Experience:  I am a Home Appliance / Refrigeration Technician of 25yrs+ with my own business and for multi-brand national companies.
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I have a Beko DW686 which produces no heat, I have checked

Resolved Question:

I have a Beko DW686 which produces no heat, I have checked the flowthrough heater and it is good so I have managed to establish the main pcb brings in the heater relay for just 5 seconds and then drops out. I have checked everything and also replaced the thermister but it still does this in every programme. I think the the PCB is looking for another signal to show the water is flowing which it doesnt get and then shuts down the heater. The spray motor has a sensor wire back to the PCB and I suspect it is something to do with this.
Submitted: 2 years ago.
Category: Appliance
Expert:  Dales-Electronic replied 2 years ago.
Dales-Electronic :

Hello My name is Ian ~ I am not on the site constantly so please be patient whilst waiting for responses to you queries

Dales-Electronic :

Could you give me the product code please so that I can check out the specifications for You ~ Ian

Customer:

Hi Ian,

Customer:

The machine was bought as graded and the supplier has peeled off the id label from the inside of the door. I have seen the date 2012 on the componenets

Dales-Electronic :

OK can you leave this with me until tomorrow the Beko engineer site is having planned maintenance right now but I will try and get a wiring diagram for it, can you confirm that the relay legs are firmly soldered into the board as this is a common fault with these, the power hits the relay but then shorts and the relay then flicks over and no power subsequently goes to the heater ~ Ian

Customer:

Hi Ian,

Customer:

I had the relay fault a few months ago and I have already replaced the relay once. I have managed to read the 12v to the relay while the machine is in operation and it is the coil voltage that disapears.

Customer:

I have run the machine with the multimeter connected to the heater terminals and you can also see the full 230 volts for 5 seconds after the fill and when the pump starts. I have already bought a heater in error and then a thermistor so I am £50 in so far. I was about to order a new PCB but I feel it is actually working OK but something is telling it to shut down the heater. When I had a look at the spray motor it has quite a complex PCB on the back of it which I am presuming is acting like a tacho and feeding information back to the main board. The motor is £85 and the main PCB is £35 so I am just trying to find out if there is any way of checking them.

Dales-Electronic :

To discount the motor put the appliance into a prewash which does not activate the heater and check that the motor circulates the motor correctly

Customer:

Yes the cold pre wash programme is fine. You can hear the motor is working fine and also I can hear the 3 way valve changing the spray patterns. Even though the motor is circulating the water fine I just wondered if it had a feedback to the main pcb to confirm it was running so that the heater would not overheat if the motor was obstructed. It is just so precise the way the heater switches off it make me think it is a safety thing. i.e heater starts and then it checks for flow through the feedback circuit - if no feedback then it shuts down. Another thing I have noticed is that when the heater switches off the time to finish for the programme also reduces by about 20 minutes.

Dales-Electronic :

The water level is checked by another component that has no connection to either the heater or motor. On a dishwasher there is no speed variable its is a constant speed motor unlike a tacho that you get in a washing machine. I still think You need to recheck the heater relay for either a loose solder joint or burn out ~ Ian

Customer:

I replaced the relay before Christmas because it was heating intermitently and it has been working fine. This time the heating went off completely so I purchased another relay and fitted it and the problem is still there. I tested the relay that I removed and there was nothing wrong with it. I have managed to test the 12dc coil supply while the machine is running and you can see it come on for 5 seconds and then disappears to 0 volts. I am convinced it is nothing to do with the heater relay. I have another relay exactly the same as the original Omron fitted which I can fit again if you want?

Dales-Electronic :

Heater error test

Customer:

The heater error pdf gets me no further on, I have done all that it asks. Are you suggesting I change the PCB?

Dales-Electronic :

I can see you other thing that can be causing the fault, you have changed the most likely components, ie heater and thermistor the only other thing is the pcb having checked that the thermistor readings are being received at the pcb end ie checking the cables ~ Ian

Dales-Electronic :

typo ~~ no other thing

Customer:

Hi Ian,

Customer:

Just give me a day or so to check the thermistor wires back to the board,

Dales-Electronic :

OK

Customer:

Hi Ian, Had the whole thing in bits again and found one of the small blue wires to the thermistor was open circuit. The wire had broken as passes through the pivot point of the door. Happy days and thank you for prompting me to check the thermistor circuit again.

Customer:

Best Regards

Customer:

Thank you for your help

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