Measure the mains voltage in AC.
If it gives 220v, desolda pin 3 of the regulator. Not in print. And measure on the main electrolytic pins if the voltage exceeds 300v. I commented
You must change
C 616.
C699.
And work with the unlinked source. That is, removing one end of R 663 and placing a 100w load bulb. in the + b.
something else ... the measurements in the secondary you have to do, taking the tuner's body or sheet as mass .... the measurements in the primary are taken as the negative of the C609 ... this chassis has many protections. ... then we will see that ... check also the L661-L631-L651-L611-L671-L681-at the source outlet and see if any are not open or loose welding ... ok ...
Nicomena, sorry for the delay, I lost my access to the account. I went crazy but managed to get it back! :) The fault was in L661! Many thanks to everyone, I consider the issue solved;)