{{:notes:pioneer-djm350-keyledscan.png|}} This is an image from a faulty djm350. Green is S2 line (compromised), yellow SCAN2 (healthy). However green trace is didactic as you can see each step is a scanned row, width about 667us. All 7 rows are scanned in about 4.67ms. Scanning is used both for keys (KEYn lines) and LEDs (Gn/GRn lines). Oh, by the way, the fault was a LED that was internally broken and conducted electricity in reverse direction, thus compromising the scan matrix.