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Conference wrksys::alphastation

Title:Alpha Workstation Conference
Notice:See note 1.* for conference notices
Moderator:WRKSYS::HOUSE
Created:Wed Sep 07 1994
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1996
Total number of notes:9122

1835.0. "Grouding Ethernet to chassis" by FRAIS::KHAN () Tue Feb 04 1997 09:02

        One AS500/500 has been causing network errors. It looks like the
        internal Ethernet ( thinwire MAU ) is the culprit. A PCI device
        works, while ping on the internal NI has >80% error rate.
        It is a technical University and so we have lots of environmental
        factors to check, but it looks like the BNC connector has its outer
        connection ( ground or shield ) connected to the chassis ground !!!
    	I always thought that the two pins from the BNC were not connected
    	to ground/chassis in the system.
        Is this correct ?
        What did we do:
    
    	1) ordered a MAU and a system board. We get 0 Ohms from then BNC
    	outer metal to grounds/shields on the system board. We also
    	verified this on a full AS255.
    	2) we had a look at different NI cards. These pins seem to have no
    	connection to the chassis ground. A KZPSM, which has the same Tulip
    	and the HALO work. So the grounding must have taken another path
    	too.
    	3) works in another network. Which means that this particular
    	network is getting power disturbances. Isolating the ground from
    	the power ( floating ) seems to solve the network errors. This 
    	cannot be done due to safety reasons. We will look at the power
    	with an analyzer.
    
    	To sum it, we think it a problem with the MAU card. Can someone
    	comment ?
    /Azfar Khan
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1835.1AS500/500 MAU ProblemWRKSYS::MURRAYTue Feb 04 1997 10:082
The AS500/500 MAU Problem was found and fixed. Apparently some of the "bad" ones
were shipped. Did a replacement MAU have the same problem?
1835.2MAU Rev C is what I want !FRAIS::KHANTue Feb 04 1997 10:476
    According to Rick Rudman, this problem was fixed with Rev.C MAU. We
    have revision B02. Also the newly ordered ones from JGO. But now with
    this new information I will try to get a C-one.
    
    Thanks,
    	Azfar
1835.3Info gets everywhere ?FRAIS::KHANMon Feb 10 1997 10:236
    Looks like our Logistics has lots of these 'bad' spares. Does anyone
    start a Logistics-purge or replacement process once such faults are
    found. As this is a new system, I would also assume that the these
    modules are being installed in the factory ( AYR ) too. I have sent a
    mail to Quality@ayo.
    /Azfar