Onkyo TX-NR656 Replace SMPS with 12v power supply

Greetings,

I have a Onkyo TX-NR656 110v receiver.

It was connected directly to 220v and it died.

After checking the smps board (BCPS-1984) it is obvious the following got damaged:

- Common mode choke (inductor)

- Power IC is damaged

- Diode is damaged

I can´t find the BCPS-1984 so i plan to use a 12W 5A power supply(220v input) and connect the power transformer to a stepdown transformer 220v-110v.

This is what i'm thinking of doing:

-sever the ac traces in order to leave only the relay circuit active and splice in the 12v and GND from another power supply.

-preserve the MPON trace to the relay circuit.

- sever the traces from the original psu that lead to the output ribbon cable

In this manner, (I hope), the main board receives power and after depressing the power button the relay will be energized and the power transformer will start supplying the rest of the other boards.

What i can't figure out is if the SWPON pin is required for the receiver operation.

I don´t think it is required, but would love some input on it.

Can't it be left out, or is it essential for function?

Thanks