Problem with service mode on Sony Crt
I need help with an issue I have on my Sony Trinitron kv-27v42. I'm trying to save a specific setting on GAMM (Gamma). I am trying to make it GAMM 2 but when I press mute and enter to save I turn it off and enter service menu and found out it's still GAMM 1. I don't know why GAMM won't save. I really need help with this.