What is the problem with the power supply board that reoccurs? Thanks in advance for your reply!
Look here:
[FIXED] Yamaha A-S700 intermittent power-on failure (and eventually full failure)
I realise how important is 1) understanding the theory behind each type of component and 2) this is physical world, not just theoretical models, so physical properties and behaviour change with time, temperature, voltage, current flowing through, etc. This and so much more are taken into account...
www.audiosciencereview.com
I have replaced it with the Y2 cap that I've linked, so far so good.
Always in standby, still alive.