Perhaps to be more specific: i can turn the speaker off to Standby manually though ! ALF

I am amazed, no one dares to comment constructively ☹️ not even BeolabPenta experts ?? Come on guys….. ALF

Thanks for all the replies, much appreciated 😁 the Penta surprisingly have recovered without explanation. ALF PS: i wonder if the “old forum” as I know has died ?!

If the problem becomes persistent and on all sources, then you may have a problem with the PCB 2 Control board in the Penta. Specifically a transistor BC 337-40; it switches the Penta on and off dependent on an incoming signal.   There are more detailed articles on the old forum that describe how to replace the transistor and where it is exactly; you would need soldering iron skills. The BC 337-40 transistor was readily available 3 years ago when I suffered the issue.   See https://archivedforum.beoworld.org/forums/t/42040.aspx but there are more and better articles in the old archived forum(s). Keep your fingers crossed that your transistor is not failing - unless your issue was a one off problem caused by a signal source problem.  

Thank you kindly for your reply….well, what can I say ? I suspected amongst other possibilities a flatband connector issue and tried to open the flap-cover without taking the whole amplifier off the penta. I could not totally open that cover housing pcb 2 but it might have had a strange impact to a degree that the penta now switches back to stand-by….figure that ?!! i will keep in mind that very transsitor - thank you for that ALF