[widar-wg] Rebbotable Effin problem/+3.3 V dropout.

[Brent Carlson]

We had a meeting with Steve and Chris this afternoon regarding 
correlator hardware acceptance, and this email is an action item from 
that meeting.

Steve indicates that the major outstanding hardware issue is this 
rebootable effin problem on Baseline Boards, supposedly due to the +3.3 
V power supply temporarily dropping out.

I searched MITR Baseline Board module history for "effin" and found 5 
boards which have a marked history of this problem:

BB20A2: first reported Oct. 19/10.  Next reported Jan 7/11, at which 
time the 1V5-B and 3V3 power supplies were replaced.  No further reports.
BB20A3: first reported Oct. 19/10.  Next reported Jan 13/11, at which 
time the 3V3 power supply was replaced, and commented "No more effing 
issues".  No further reports.
BB2026: first reported Jan. 13/11. Replace 3V3 power supply.  Seems to 
fix the problem, no further reports.
BB2020: first reported Feb. 9/11.  Showed problem twice in 2 weeks.  
Replace 3V3 power supply.  No further reports.
BB2038: first reported Apr 20/11.  Reports consistent effin problems for 
a few weeks.  Replace 3V3 power supply, "seems fine now".  No further 
reports.

There were also 3 Station Boards where this showed up, and where 
replacement of the +3.3V power supply seems to have fixed the problem.

So it would seem there is compelling evidence that it is the +3.3V power 
supply.  As I indicated in a previous email, the +3.3V power supply is 
operating well within limits (on the Baseline Board: 11 A output, 60 C 
semi case temp, at 25 C Tamb), so it *shouldn't* be the problem, 
according to the mfg...

However, in order to close this case, has anyone been seeing this 
problem occur?  If so, have you been noting it in MITR, without fail?  
Its ok...'fess up now if you haven't been noting it :-)

In order to hopefully nail this down, every single time it happens, it 
has to be noted in MITR history for that module, noting it is the 
"rebootable effin" (or "effing") problem, and at some point the +3.3 V 
power supply must be replaced and noted.

If some evidence develops that indicates it isn't the +3.3V power 
supply, then we need to search elsewhere, and even try to trigger on the 
event actually happening in-system with a single-shot capture DSO on the 
+3.3V line.

--Brent

-- 
Brent R. Carlson
Brent.Carlson at nrc-cnrc.gc.ca
Tel: 250-497-2346                  |  Fax: (250) 497-2355
Design Engineer                    |  Ingenieur Concepteur
National Research Council Canada   |  Conseil national de recherches Canada
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"When and where humans are involved, mistakes inevitably happen"