Hello Martin,
Here are the schematics for the Opus 7, unfortunately it is in German,
http://188.142.38.174/nvhr/Telefunken_Opus7.pdf
Heres a link to the website tht has many European radio schematics.
http://www.nvhr.nl/gfgf/schema.asp
Those are great sounding radios, also love the Grundigs and Saba's. I've got two of the Opus 6