Btw - the 74hc165 shiftregister circuits i know from earlier electronic experiments, had a slightly different layout.
There should be a 10k pullup between the SER pin and +5V of each shiftregister
And a 100nF capacitor between Vdd and Gnd as close to the chips pins as possible.
http://www.ucapps.de/mbhp/mbhp_dinx4.pdf

Attached Files Shift-Register-Board-Layout extra.png
Last edited by Buncan; 05/03/17 03:27 AM.