When we buy new device such as NEC SP4020 we often through away most of the documentation but the warranty.
Very often issues with NEC SP4020 begin only after the warranty period ends and you may want to find how to repair it or just do some service work.
Even oftener it is hard to remember what does each function in Speaker NEC SP4020 is responsible for and what options to choose for expected result.
Fortunately you can find all manuals for Speaker on our side using links below.