something we test for while assembling is for malformed button pads. if the black conductive pill is slightly off, there’s a potential when pressing a pad at an odd angle that the pill will hit the small exposed pad of the led. this will bridge the led and button systems, causing random-looking key triggers in that column.
the best way to test for this is using _40h_test.mxb in toggle mode. press every key at a variety of angles. you’ll see vertical led flutter if there’s a problem.
here’s how to fix it:
1. howto - disassemble the 40h
2. orient the logic board down, towards you, and remove all of the pcbs and cables.
3. with an exacto knife, shave away a small splinter of the black pill of the problem pad.
4. reassemble. test thoroughly before reapplying the silicone glue layer. we use 100% silicone aquarium glue, which is cheap and very good.
