having a old layout and converting it to a dcc system is it hard to do or not?
It’s a lot easier than going the other way. Maybe that’s why nobody ever goes from DCC back to DC.
If it’s a small layout, you can just wire all the blocks together and plug them into the DCC system. For a larger layout, you will want to divide your DCC system into “power disctricts,” but having the blocks already separated, all you have to do is wire some blocks to one district and other blocks to another district.
If you have signals wired up to the blocks, though, you will need to make special arrangements for those.
Piece of cake. Wire it up & leave the block switches in place & turn them all on. If you ever have a short or other problem you can isolate the source by turning the block switches off . You can also use one position of the switches for DC if you want.
The other good thing about a layout built for DC is that installing working signals is about five times easier, since the sections are already insulated from each other.