Hi Brach,
Thank you for your reply. Checked continuity. I have continuity between pin 3 and round pad of bypass switch and between pin 4 and tap switch. Had faulty multimeter so disregard previous readings. Resistance between both pins an pads is 0.5 ohms. I have been using an antistatic mat during assembly to make sure the chip didn’t get damaged. Been servicing pcb’s on our studer A820 MCH for last while and haven’t had a chip fail yet. Slightly perplexed