1. "function" &"select" button 一齊按入 system mode. (press "select" first )
2. Press "func".(LCD show "REVERSE", "ST NOR/REVE"). <-- this is CH1.
3. Press "Select". (LCD show "REVERSE","TH NOR/REVE"). <-- this is CH2.
4. In step 2 or step 3, Press "+" or "-" to toggle setting "NOR" or "REVE".