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Subject: FW: STIS Anomaly Update
Date: Wed, 23 May 2001 08:37:48 -0400
From: "Rodger Doxsey"

FYI, next steps with STIS

-----Original Message-----
From: Larry Dunham [mailto:larry.dun@jnt.com]
Sent: Tuesday, May 22, 2001 7:52 PM
To: STIS.Anomaly.team@jnt-is2.jnt.com
Subject: STIS Anomaly Update


Update on STIS Anomaly Testing:

Test #1, to command the PDU relay closed was executed today with no
change in current or relay status. EPS is still looking at the DIU
reader data in detail. Now that Heater A is enabled on the STIS side
2 and the Hold power relay on side 1 is open, I believe everyone feels
we are in a better state.

A meeting was held this afternoon between Keith Kalinowski, Richard
Broderick and HST H/W engineers to discuss test #2 risks. We now have
Project approval to proceed with test #2 (cycling the PDU relay). The
thought of a third test to verify the functionality of the CDI was
brought up. Keith Chamberlin took the action to lead the effort to
determine if this was desired.

It was also pointed out that on PSEA entry, PDU STIS primary and
redundant power on HLD's are sent out by the PSEA. Therefore there is
no additional protection gained by opening the PDU relay after test #2
if there is no success. Therefore we will NOT be adding an open (OFF)
command at the end of test #2. The fact that we can not prevent the
Bus C fuse for STIS primary power from being exposed to a potential
short upstream of the Hold Power relay in the case of an inadvertent
entry into Hardware Sunpoint has increased the desire to expedite a
decision on a Bus C test. Not performing a Bus C test will not
necessarily save the fuse for later use. Given this, the FSW group is
being asked to start work on the high speed format option.

Also for test #2, it is now being advocated that we go to T format. T
format has the relay status at 1 hz while giving the 40 hz TMDIAG data
for the DIU reader data. DMS (E. Graham) and John Bacinski (TC for
test 2) will evaluate this and potentially look at new windows for
Thursday. If anyone has an objection to the use of T
format please let me know ASAP.

A "touch-up" FRR will be held for test #2 on Tuesday morning at 9 AM
in S107 if available (SIM has priority, if it is use then a note will
be posted with a new location.)