I have a Signet SL80 (1988 vintage)
I have an SL80 it works like this:1. Enter depth alarm mode by pressing and holding the "smartpak" key for 2-3 seconds with 4 audible beeps. The alarm indicator will flash.2. Press the "H/L" key to select hi (H) or low (L) alarm.3. Press the "up arrow" or the "down arrow" key to increase or decrease the alarm value.4. Press the "R/S" to set this value.5. Press and hold the "smartpak" key until normal operating mode resumes.Not sure if your model works the same, but if the key references make sense to you I would think it would work. Good luck.Jim