Schaerer Opal , Solenoid valve gets no current

Hello, I am new in this forum and have a problem with my Schaerer Opal.
The solenoid valve directly in front under the marc container gets current after switching on (24 Volt are applied and open) but during the heating up phase the voltage goes away completely and the valve closes again. Then the rinsing process starts and the water is
pumped
against the closed
valve.

Is this a fault on the control board ? Can it be repaired or replaced ? If so, where

can I get one ?

I am grateful for any good advice and

information:

)Andreas from Leverkusen

The front valve is the relief valve. This opens after a brewing operation to allow the residual water of the brewing group to flow into the drip tray.
It should be closed during rinsing
.

What happens then when it rinses? Is the non-return valve still intact? I mean the brass block in the back.

Thank you for the information about the check valve, I was probably misinformed,
the pump runs against resistance
during
rinsing, the motor pump noise becomes quieter and there is water in the drip tray under the brewing group. But the brewing group is free and works perfectly in another machine of my colleague
.

The rear metal block I had not yet set my sights

on.

But when I loosen the hose in front of the front valve, all the water comes towards me with pressure during the rinsing process! Then the rinsing water must also pass through this valve, right? Therefore I also assumed that it should be open.

Thank you for the information about the check valve, I was probably misinformed,
the pump runs against resistance
during
rinsing, the motor pump noise becomes quieter and there is water in the drip tray under the brewing group. But the brewing group is free and works perfectly in another machine of my colleague
.

The rear metal block I had not yet set my sights

on.

But when I loosen the hose in front of the front valve, all the water comes towards me with pressure during the rinsing process! Then the rinsing water must also pass through this valve, right? Therefore I also assumed that it should be open.

QUOTE (Schlawi @ Saturday, 11 July 2020, 19:45 hrs)

The front valve is the relief valve. This opens after a brewing operation to allow the residual water of the brewing group to flow into the drip tray. It should be closed during rinsing. What happens then when it rinses? Is the non-return valve still intact? I mean the brass block in the back.

I have now also replaced the rear check valve, but the problem still exists. There is an obstacle in the pump system and no water comes out of the outlet nozzle during the start rinsing process.
As well as
no coffee with the purchase. I must relieve the pressure building up over the steam nozzle with hot water supply to finish the process.

What could still be the reason . All 3 valves changed, circuit board changed, brewing group completely free with screw-on piston. I am helpless

Attached is the watercourse plan. The only thing that can block between pump and brewing unit is the non-return valve.