Private Sub Worksheet_Change(ByVal Target As Range)
If Target.CountLarge <> 1 Then Exit Sub
If VarType(Target.Value) <> vbString Then Exit Sub
If Not Target.Value Like "*'*" Then Exit Sub
Dim T() As String: T = Split(Target.Value & "''", "'")
If T(0) = "" Then T(0) = "0"
If T(1) = "" Then T(1) = "0"
Target.NumberFormat = "[m]\'ss"
Target.Value = TimeSerial(0, T(0), T(1))
End Sub