From: utzoo!decvax!cca!cak@Purdue@sri-unix
Newsgroups: net.unix-wizards
Title: Re: LHDH-11 on Vax Unibus
Article-I.D.: sri-unix.4271
Posted: Sun Nov 21 01:43:41 1982
Received: Mon Nov 22 02:44:29 1982

From: Christopher A. Kent <cak@Purdue>
Date: 17 Nov 1982 21:47:17-EST
Mark,

Your problem sounds exactly like the one we had when we got our LH/DHs
last December. You plug it in, and the Unibus hangs; you unplug it,
and everything is fine. 

Probably if you go a little farther, you'll find that the LH/DH has absolutely
nothing to do with it -- take out the edge connector card that goes into
the LH/DH and try connecting and disconnecting that from the Unibus cable,
without having it plugged into the LH/DH. That was our problem. Turns out
the PC etches were a bit too wide, and the Unibus INIT signal (active low)
was tied to ground. We fixed it by drilling a hole in the errant trace
and soldering a piece of wire wrap wire in place.

Of course, when we called ACC about it, they couldn't believe it -- I believe
the quote was something like "We extensively test every piece of hardware
that leaves here."

Hope this is it.

Cheers,
chris