CL84209 Handset LCD Disassembly

I’ve mapped out the custom segments that occupy the lower half of this LCD, from the handset of an AT&T CL84209 cordless phone system. With that knowledge in hand, I wanted to dig a little more into this subassembly. When I removed it from the handset circuit board, I saw tantalizing hints of identification information that was mostly illegible through distorted plastic.

Four small sheet metal loops stamped in as part of the top metal shield held this assembly together. Once I popped those four loops freed of the tabs molded into the bottom-most piece of plastic, I could lay out all of its layers.

From left to right (bottom to top) we have:

  • Glossy injection-molded plastic bottom layer that is also most of the structural support.
  • Thin matte sheet of plastic.
  • Thicker (~1mm) clear sheet of plastic acting as conduit to distribute light from the single LED.
  • Thin frosted sheet of plastic acting as diffuser.
  • Glass LCD assembly with built-in I2C controller somewhere under the black blob.
  • Rubber surround (glued).
  • Topmost metal shield.

And now the objective of the exercise: a clear view of everything printed at the bottom of this handset LCD. Printed on a sticker is the following:

GWMS7728B
09470315313

Printed on the Flexible Printed Circuit (FPC) is:

7728-FPC-B-A152-4709

I see the logo of stylized “LCD” on both the FPC and etched into glass.

I saw the same logo on the base station LCD. And whereas that module was designated 6334, this one is clearly designated 7728 based on that number being repeated three times: etched into a layer of glass, on the white sticker, and also on the FPC connection.

This is a lot of additional information! Unfortunately, more information doesn’t guarantee success. Armed with this additional data, I still failed to find any details on this LCD module. But I’ll leave them here as a record hoping that my search skills will improve enough in the future to find something. But for today, I have to concede that I’ve tried everything I know. Lacking an official reference, I can only summarize all of my guesses about this device.

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