Good old Technics forum!!!!
My great keyboard lost it's voice,everything loaded and appeared to work ok but no sound!. Having an idea this had happened before
to a forum member,so checking the past posts success!!!.
Mike Daniell in Australia had the exact same symptoms back in 2009.The fault was traced to IC643, the negative 15volt regulator on the FAJ board. Mike quoted a generic part as LM7915
but be carefull as Panasonic use a high spec for the component.
Panisonic use a KIA7915PI (TO220) made Korea Electronics.
Good new this is still made and here in the UK. W D Greenhills have them on the shelf. These are the High spec items,you might get away fitting a generic but it's life may be shorter and if it goes down it may take other items as well
costing a lot more in the long run.
Regards to all John.
P.S. Part has now been changed, and the KN7000 is singing with
full force once again.

Great news and very valuable information.

Thanks

That's great news that you found this past posting that provided the fix to get your KN7000 back working again.

Hi Nigel.Thank you for this site as it helped me very much in quickly finding the fault and correcting my KN7000. I have been talking to my engineering friends as to the reason for only using the genuine part,Panasonic in its wisdom tend to run the components slightly hotter than other companies. The generic part has a lower working temperature and as it is not mounted on a heat-sink this alone would shorten it's life, also the KIA7915PI has an insulated body where the generic parts do not and also use the heat-sink tab as a secondary connection(ie: poss out or ground) In the case of the KN7 there is no room on the board for a heat-sink but even so an uninsulated tab could in certain instances short out or cause other problems.
regards John.