Bare glass LCDs don't really like DC bias - they will survive a short test but its not good for them. Also the link between supposedly common pins is almost certainly
Indium tin oxide which may well not be conductive enough for your multimeter's continuity range to register.
The best approach is to AC couple adjustable amplitude antiphase squarewaves of about 30 to 90 Hz to the segment and common or digit contacts you want to probe. Start by providing a leakage path to ground for all pins e.g a 1M resistor per pin, connect two pins to the antiphase signals and increase the amplitude from zero till one or more segments are visible. If you see two segments, you've found two segment pins but haven't found the common or digit pin. If you see lots of segments, you've found two separate common/digit pins. In either case turn down the amplitude till the segments are faint then move one probe about until a single segment appears with reasonable contrast. Once you've got one segment, you should adjust for best contrast then start mapping out the display.
Here's a fairly crude circuit using a quad OPAMP to generate adjustable antiphase drive waveforms for testing only. RV1 is a 10K pot for the amplitude and R12,R13 are actually the individual pin bias resistors, not part of the probing signal generator.
![](https://www.eevblog.com/forum/other-blog-specific/in-the-weee-k1-follow-up-testing-the-displays/?action=dlattach;attach=177314;image)
If you've got a square wave output signal generator that can go up to about 5V peak to peak, you can skip all that, and simply use 1K resistors and 470nF caps in series with each probe, and return all the bias resistors to the mid-point of a potential divider using 1K resistors across the signal generator output.
Application circuits:
For a non-multiplexed bare glass LCD you can use a job lot of XOR gates to drive the segments and a 50Hz squarewave signal to drive the XORs and the common. If the segment is in phase with the common, its off, and if antiphase (i.e. other input of XOR is '1'), its on. The signals can be generated in a MCU on an I/O port rather than by XORs. Care should be taken to keep the duty cycle at exactly 50:50 to minimise any residual DC bias.
Multiplexed bare glass LCDs are a *LOT* trickier to drive with multi-level stepped waveforms required, and although you *can* get there with divider chains, CMOS switches and OPAMP buffers, it makes far more sense to use a proper LCD driver chip or one integrated into a MCU.
Edit: Corrected the bias resistor designators in the description + some clarification.