On Mon, May 25, 2015 at 8:07 PM, Michael Thompson <michael.99.thomp...@gmail.com> wrote: > Today we pulled all of the M113 flip-chips and tested them because SN7474 > and SN7400 ICs seem to be a problem in these early DEC systems.
I have found from debugging a PDP-8/i and multiple PDP-8/L systems that 80% of my failed ICs are SN7474 and SN7440 parts, and most of the remaining 20% are SN7400. I think I've replaced 0-2 parts that weren't one of those three. Do you have any writeups on Warren's FLIP-CHIP tester? I made a simple rig with a 1990s-era Ming IC tester and a 16-pin clip-lead harness that can test each chip on a simple (M113, M117...) FLIP-CHIP, but it can't test complex boards like the M220 or M706/M707. Fortunately, most of the failures I've run into are a small handful of TTL on the simple single-height boards, which this rig can catch. I've been thinking about a smarter rig but haven't tried to build one. -ethan
