Private Sub SpinButton1_SpinDown()
TextBox1 = TimeSerial(Hour(TimeValue(TextBox1)), Minute(TimeValue(TextBox1)) - 1, 0)
End Sub
Private Sub SpinButton1_SpinUp()
TextBox1 = TimeValue(TextBox1) + TimeValue('00:01')
End Sub
Private Sub UserForm_Initialize()
TextBox1 = TimeValue('10:00') '1 'Initialiaze la valeur à donner à ton TextBox
End Sub