I had an old CO detector that went bad so figured I'd scavenge it. There's a nice little 7 segment 3 digit LCD display on it with a 5 wire ribbon cable. The display is mounted to a bit of PCB and of course underneath the display is the driver chip so I can't see what chip it is. Only 4 of the 5 ribbon cable wires actually are connected so I figured it's I2C. On the main board of the detector was an I2C EEPROM so I was able to figure out the wiring to the display (SDA/SCL/VCC/GND) easily enough since it shared the bus. I ran some i2c scanner code on the arduino and it easily found the driver chip, it's address is 0x3E.
I tried a couple libraries and things to get it going and nothing I've tried lights up any segments.
Now for the big question. Does anyone have any idea how I might be able to figure out what that hidden driver IC is w/o desoldering the display from the PCB. It's such a nice little assembly I'd really like to keep it as-is. The display itself is common cathode, 24pin, and if I ground pin 24 it illuminates all the segments at once. I know, doesn't really tell you anything about the driver chip probably.
Thanks for any suggestions.