User Manual for the Crate Powerblock 150 is available at:
http://www.crateamps.com/pdf/manuals/CPB150_OM.pdf
Are you sure you aren't talking about the Crate GX900H?
http://www.crateamps.com/pdf/manuals/GX2200H_OM.pdf
Just googled it as I am having a slow day at work
Cheers
Vic in Sydney, Australia