Are you thinking about the wrong types of transistors fitted as 5TR4, 5TR5 and 5TR6 in the safety circuit?
They can cause the primary fuse to blow for no apparent reason and are found in
some Beomaster 2200 with serial number earlier than 1470001.
Servicemanuals give out wrong part numbers as well.
5TR4 should be a 8320408 (BC 256 or similar)
5TR5 and 5TR6 should be 8320409 (BC 174 or similar).