I have an iP4500 with a defective print head, so I opened the power supply and checked the transistor. In my supply the marking is clearly visible. The transistor is marked K3562 8:J. In Japanese transistor numbers "2S" is often omitted. The transistor is 2SK3562, data sheet here.
The same power supply K30290, AKA Canon parts number QK1-3520-000 is used in the MP610, so maybe you will find something of interest in this thread?