A close listen revealed that the unit was not totally dead, pressing the power button the unit would click on then immediately off (but nothing on the display). This could be repeated a second time but then the unit would not respond. Pulling the power lead would allow this sequence to be repeated.
So the unit was alive and intelligent.
A quick google gave me the manual to download from the excellent site, electrotanya.
http://elektrotanya.com/panasonic_sa-pt470.pdf/download.html
Panasonic / Technics manuals are absolutely superb.
I may do a post about my beautiful Technics SC-CH900 that I finally bought after 22 years ! :-) anyway..
So I opened it up and stated to take a look. Nothing obvious so decided the best plan of attack was to take the PSU out to get some proper access.
Admission: I took a stonking 360v dc hit from the main cap, Warning, always approach with caution, measure the high voltage DC caps, and discharge as appropriate.
This fault will leave the main caps charged. I usually check but got sloppy.
So nothing jumped out visually, the mains went through a hefty filter and feeds standby power section of the PSU, the main psu is switched in through a relay, the relay only stays in if the PSU behaves correctly.
I did some passive checking but again nothing jumping out.
A move not without risks but I decided the best way forwards was to bypass the relay and see what wasn't powering up, the brain was obviously not happy and shutting everything down.
Using the drawings I checked all the rails and found the 18v fan power to be absent. I checked the rectifier diode D5805 and found it short. Fitted a repalcement and all good.
