[morzh]

Well, here's some. Although there are some mistakes there.

http://www.introni.it/pdf/Radio_diagrams_1955.pdf

I found some in DjVU format but cannot get back on that website - forgot what it was. The same manual though.

The 720 is said to have the same sch with
C580 or C716. While the PCB does look the same format-wise, it only has 4 tubes and ours has 5 tubes.

However C-722 sch does look similar, 5 tubes with the 12BE6 pentagrid and clock connection.

Could be it!