shj@ames.arc.nasa.gov (Steve Jay) (07/19/89)
In v8n64, Dan Davison (dbd%benden@lanl.gov), says that his mysterious XY753 problems went away when he switched from a Dawn adapter to an Ilimite adapter, which has the controller plugged driectly into the backplane instead of at the end of several inches of PCB trace. However, he says you then have cables "buried in deep inside" the chassis where they might short out or damage neighboring boards. AnDATAco [10054 Mesa Ridge Court, Suite 102, San Diego, CA 92121] makes a model ET1100 Bus Adaptor specifically designed to install XY753's in Suns. It allows the XY753 to plug directly into the backplane, and has cable clamps & a nice, Sun-compatible, brown end plate (with holes for the cables). This solves both the original problem & the dangling cable problem. By the way, any adapter which has long PCB traces can cause trouble not only for the board using that adapter, but grief for the entire VME bus. Those traces act as antennas injecting random noise onto the bus. While we're on the subject of flaky disk problems, I'll mention two other sources of weird SMD disk problems that have bit us. Both happened with XY753's, but they could occur with any SMD disk/controller combination: 1. Bad terminator for the SMD A cable. I have seen this on SMD drives connected to lots of different computers. Although the terminator is a simple, passive, device consisting of only resistors, it seems to fail at a remarkably high rate. I've seen a lot of disk service folks routinely carry around one or more extra terminators. A bad terminator can cause all kind of problems. 2. Both the A & B cables have green ground wires at the drive end. Make sure these ground wires are firmly attached to the drive. There should be a grounding screw near the cable connectors. A non-attached or loosely attached ground wire can also cause flakiness. Steve Jay domain: shj@ultra.com Ultra Network Technologies Internet: ultra!shj@ames.arc.nasa.gov 101 Daggett Drive uucp: ...ames!ultra!shj San Jose, CA 95134 408-922-0100