AH2700 issues

[pmelgeek]

Just curious, has anyone else had problems with the AH2700 coming up with "L to GND Short" errors? We've been using these without a problem for quite a few years now, except for the last couple months.  We sent it back to AFPSL, got a different one, and still have the same problem.   AFPSL couldn't find a problem with the old one. 

We put a multimeter on the Low input and measured the resistance to ground, and it's definitely shorted.   Oddly enough, it started working again after we did this.  It was almost like there was a stuck relay and we activated it when we measured the resistance.   We started running the relay exerciser along with the regular self cal in hopes that would be the end of it, but the problem keeps cropping up.   Sometimes the multimeter trick works, and sometimes it doesn't.  The error will persist sometimes for days, then it'll just vanish and everything will work fine. 

I figure it has to be something local since this is the second one in a row that's done this, but what!? We've checked grounds, line voltage, moved it from bench to bench, in and out of consoles, different cables, continuous and single measurement modes, turning it off everyday vs.  leaving it on, and a host of other things, but no luck.   

Any ideas?

[Snap]

I've seen this a couple of times on my 2500A, just with a couple of our GR 1409's.  Haven't figured out what is causing it yet.