WMF Bistro Easy DFM Error

WMF Bistro Easy 8300 DFM Error

Hallo,

has the error on my Bistro Easy that it starts normally, but as soon as I want to draw hot water or an espresso ect. appears DFM error.

Have already pressure reducer, flow meter, espresso pump, "heat exchanger", hoses, connectors, solenoid valves disassembled, cleaned and reassembled.

In my opinion, the following causes still remain:

Water supply too weak - but I have 6 bar in the cellar and assume that the minimum requirement for the bistro of 2 bar will still be met on the 2nd floor ... at least it splashes a lot when I hold the hose into the sink and turn it open.

Flow meter or flow meter defective - someone knows if you can control this with a multimeter ... or what values it should have.

Espresso pump too little passage - it runs noisily normal, gets louder when you turn off the water.


When you get hot water it runs about 4mm diameter (a little more at the beginning) for 7 seconds, then the DFM error appears.

	QUOTE
Flowmeter or Flow Meter defective - somebody knows if this can be controlled with a multimeter ... or what values it should have.

I don't know the Bistro in particular, but you can easily test a flowmeter.
Measure the voltage at the signal pin and gently blow it into one of the connections, or turn the impeller in disassembled condition.
The signal voltage must now change back and forth between 0V and the supply voltage (5 to 24 V).

A test in normal operation is only reasonably possible with an oscilloscope, or to a limited extent with a good multimeter if it offers frequency and duty cycle measurement range.

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Quick Mill 05000 "Unique Edition", WMF Ecco

If you look at the flowmeter from the 3 connections, I measured 0.40V left-right 6.69V
between the middle and the right 5.98
middle-left 0.40V left-right ...
blöderweise none of the values changed when blowing although the buzzing was clearly audible

QUOTE

blöderweise none of the values changed when blowing although the buzzing was clearly audible

As described, the signal voltage cannot be measured reasonably in normal operation (fast flow).

Therefore, the advice is either to blow extremely weakly (so that no noise is generated) or, in order to know exactly what happens, to move the impeller past the sensor by hand (or hold a single magnet instead of the impeller). Then you can measure the signal voltage for unattenuated and attenuated condition individually.

But it does appear that the flowmeter is defective.
Do you want to take a picture of it, or can you read a label?

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Quick Mill 05000 "Unique Edition", WMF Ecco

Picture 1


Picture 2


Left connector: 2x grey/white cable
Middle connector: 1x purple
Right connector: 1x red

Also turn by hand - slow, right turn, left turn No matter which cable combination does not change the values ... now on both cables 7.62 V


>has carried out several tests in service mode 8 : brewing valve/DFM carried out

You can hear the flowmeter whirring and water coming out at the front, the display shows DFM: 0 for a short time

Hello.
If in the component test 8 : brewing valve/DFM only a 0 appears although water comes out of the outlet, the DFM is 90% defective.
Having first experienced that the evaluating front panel is defective.
In the test you would have to see 1 and 0 changing relatively fast.

However, I no longer have the color allocation in my head.
Could it be that you have built in a plug-in error??