Die Oberklasse

12/03/7 08.55 UK
Connect 40 UHD
Log: 54010
Screen goes blank after the TV has been switched on for a minute or so.
Applies to DVB, possibly only HD(??) ; audio still present.
Would appear to only happen the once, and the image reappears after a few seconds
Digital signal is strong

Kindly forward to technical

Further info:
Defect still present despite reinstalling firmware 4.2.10
Affects HD DVB in UK
Happens generally two times less than a minute from switching on; ie screen goes blank, comes back on, then a few seconds later goes off and then back on again
The signal strength being received during this time is uniform and does not drop off
My other TV ; ART 48 is not affected
Both are SL4 chassis

If only one of your sets is affected, it might be a hardware fault.

Is it only during the reception of channels? What about a HDMI source?

Yes only connected to DVB broadcasts (in HD) and not with any HDMI connected devices (Blu Ray) or when streaming Youtube etc

Only affects the Connect UHD (both purchase new 2017) and seems prevalent when switched first switched on for the day; for example this morning I have just switched it on and the image went blank 4 times in 2 minutes then remains steady. When I switched it off and on again the fault didn't present itself which makes me wonder if its linked to updating overnight as I noticed the blue light illuminated at 2am; who knows

Here in the UK we have had ongoing issues with HD reception and Loewe TV's for many years. I had a Individual Slim which had to be returned for a refund as it was unusable in HD, exhibiting the same fault but constantly every few minutes, however things seem a lot better these days I must admit

Other than this glitch everything works perfectly and I can live with it for now so long as it doesn't get worse

Did you check if it might have to do with PayTV or FreeTV (encrypted or unencrypted content)? You might exchange your CI-module and/or SmartCard between both TV's.
From your description, it does read to me quite similar to Handshaking problems.
Which DVB are we talking about: DVB-S2/DVB-C2/DVB-T2? If DVB-S2 (satellite): do you have quad-LNB?
Does it make any difference if your second TV is receiving at the same time? No joke, here. Depending on your selected DVB-source and the lining in your house, it might be that you cannot simultaneously feed both TV's twin-tuners with independent signals. If your Connect can for any reason use only one tuner of the twins, the Symptom might have something to do with trying to receive EPG-info via the second tuner.
Any serious hardware failure seems rather unlikely to me from the description…

DVB T2
Digital tuner board is to be replaced by Loewe

It is the mother board that is thought faulty as the defect has been determined to affect all inputs eg HDMI, DVB, alon with digital apps eg BBC1player

New board on order from Loewe

As I thought...

New main board fitted today which has corrected the fault