HP41 band aid ... ?

[ThomasF]

(02-08-2023 12:11 AM)brouhaha Wrote:  I think the other side had another unmasked section. I haven't seen it since 1982, though, so I'm not 100% certain.

Yes, the flex on one side has the "long" pads of which only a short bit is unmasked (gold plated) and the rest is "leaded" for easy soldering of wires. This side also has the text and pad-numbering (1 and 21), and it looks as if the flex is manually cut, since the sides are not perfectly straight.

The gold-plated pads have corresponding pads on the other side, and the pads are connected by via-holes, so the idea is to place the pads right between the 41 keyboard PCB and the module bay flex, and "extend" the pads for easy access for adding something inside the calculator.

Tried to measure the flex with the following result:

Code:

         Overall width (W): 38.9 mm
         Overall hight (H): 31.1 mm
            Pad length (X):  5.1 mm
         Stripe length (Y): 22.5 mm
Overall CC (pad1 -> pad21): 35.11 mm
           cc (via to via):  1.76 mm

       
(Edit: updated picture with cc)

Cheers,
Thomas