Many modders marked various problematic to the installation of the ModBo modchip; bootrate very low, problem to update firmware over v1.38, unexpected blocks, blocks during loading, etc..etc...etc..
Pupazzo from consolelab.it has found a solution!
connect 5v to ModBo from Ps2
ps: don't forget to connect the H point also in PAL version
check out the attachement for other instructions
my english it's very bad today, excuse me.
FOR ITALIAN PEOPLE HERE