Reading through this thread it seems that:
- the 197A has a backlight, and some here have needed to replace the inverter driver to supply the correct voltage to the electroluminescent backlight
- there aren't any posts about adding a backlight to a 197 (as opposed to 197A) display. Did I miss such a post?
Adding a backlight to a 197 appears to involve two primary steps: install appropriate inverter to drive EL strip, and trim/seal/install EL strip behind LCD display. All of the EL drive inverters I see either require 12V DC or 120V AC, and I'm not sure I see a convenient source of switched power of either sort in the base 197. I'd want the backlight to turn on/off with the meter's power button so I'd need to power the inverter somewhere after the meter's power switch. If anyone has installed an inverter and EL backlight in a base 197 (not the 197A), please share with us how you powered the EL drive inverter and where you managed to stuff the inverter into the meter's case.