Accuphase E-305 Integrated Amplifier Schematic

I have an Accuphase amplifier E-305. This was made around 1987-1990. I'm an electronician and as a such, I'm looking for the complete technical datas provided for technicians who services the amp (board layout, electronic wiring, components implementation). Does someone help me to find these schematics ?
This amp is so old that it is not possible to find anything and there is no more service provided.
Please send your answer directly to may mail :
frombelgium 'at'

In advance, thank you very much for your help
Best regards. Pierre