Update
With the mains on, pressing reset on the back starts the 150. But if I switch it off/on using the mains switch, it will not start without another reset.
Standby off/on works OK.
There was a short power failure (10 seconds) this night. Normally the 150B is in standby mode.
This morning it will not power on. No relays clicking or anything. I have checked the fuse on the back, and it measures OK. And there is power in the outlet.
Does anybody has any ideas? Are there more fuses inside?