[evlatests] All EVLA antennas

[Pat Van Buskirk]

The operator on duty during this observation doesn't believe there were 
any checker messages or alerts which would have pointed out these 
errors. We were in VLBI phased array continuum.

I agree with Ken, that a test on maintenance day would help us 
understand the problem and how we can identify it in operations.

Cheers,
Pat


Rob Long wrote:
> At about 1:01 PM local time, a rectifier in the -48 vdc power supply in 
> the deformatter rack died.  This caused all deformatters to go down 
> losing 4 IFs to each EVLA antenna.  We had exceeded our N+1 redundancy 
> by one antennas worth of deformatter cards (actually one deformatter 
> card), so when the rectifier died the remaining rectifiers could not 
> handle the load.  We had been watching the loading on the power supply, 
> but obviously missed it after ant 21 was brought online.
> 
> Dennis Mobley helped us troubleshoot the problem and installed two 
> rectifiers into the power supply (replacing the broken one and restoring 
> redundancy) and cycled power to all of the deformatter cards.  I 
> verified that all deformatters were up and working again and notified 
> operations that the antennas were back online.
> 
> I wasn't made aware of the problem until about 3:30 PM when I was 
> notified by Steve Durand that all of the deformatters were dead!  I 
> realize that we were in line mode, but shouldn't we have had some 
> indication that all EVLA IFs were missing?  Do the T5s still get flagged 
> as out of range on the EVLA antennas?  If so, will they continue to be 
> flagged after Modcomps go away?  We need to take a closer look at this 
> incident to ensure this doesn't happen again.
> 
> Rob
> 
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