i found out the insulation on the dc-dc coils was to burn,and made a short intermittent.(sometimes,depending on how tha colis was mowed.
how i start a new thread,i forgot. curse a have a nother amp.undnown and wont start,if i lift legs of rectifiers it start the dc-dc.converter. low resistans c-d and if i lift all base in start the dc-dc. about 52-58 volt mittle leg in the rectifiers..but goes higth as 70 in start