YAESU FT-757GX & FT 757GX II
1. Unplug the DC power cable from the radio.
2. Remove the top cover (see service manual for cover removal)
3. Locate the Black slide switch on the display panel, (to the right of center and halfway down the backside.
4. Use a screwdriver to set the switch to the left most position.
5. Reassemble the radio.