How to find the tables of datasource

Hi

can anyone tell me how to find the tables from where the datasource is extracting data?

I have a datasource 0CO_PC_ACT_02 which i thought was extracting data from MBEW, but my MBEW table has only around 1000 records but while scheduling the data load of infopackage my PSA shows more than 4000 records.

How does this happen?

Thanx in advance

Sujai