Minutes of the Tracker
Meeting
See the lists of actions
below.
(1) Progress on Tower-0 &
plan for debugging the bad cable
Emilio reported that the
Tower-0 assembly and alignment activities are finished. A list of open issues was sent to SLAC. One issue was that it was impossible to
install any of the 8 studs for the side flexures because of the Nytemp patches
that provide such a good locking feature that it is impossible to get the nuts
threaded on either end.
Today they started running
the comprehensive performance test (CPT) in the tower upright position. The top cable bending was done on Tuesday,
and the good news is that it did not damage anything.
Luca reported on the CPT,
which was started today. So far they
measured the leakage current on only one side: 20uA without the dark box. They saw no change in current with the lights
off. The current matches expectations. They will repeat this test on all 4 sides. One
goal of the present CPT is to check the execution time, in addition to the
performance tests. Luca said that the really
good news is that there was no change in the incidence of dead or noisy channels
during the assembly. The trays all
survived the handling without incident.
There is still the problem
that cable 3 doesn’t function. In
general they get no data back from even the Layer-0 GTRC, although there was a
mention that occasionally the GTFE register load and read works. They are able to write to the Layer-0 GTRC,
because they can write registers via that GTRC and then read them from the
opposite side. They will extend this
test to all layers. Robert suggested
that the problem must lie with the data line between the Layer-0 GTRC on Cable
3 and the TEM. It could also be a
problem with the data-line bias on the top-most GTRC. However, the flight cables bias that input
via resistors in addition to and redundant to the internal self-bias of the
GTRC data receiver, so it seems unlikely that both would fail. Robert suggested installing a breakout board
and looking with a scope at the data coming back from the GTRCs.
Robert requested the
(2) Tower A
preparations & issues
We went through the
Power-Point file of issues that Emilio sent.
The following is some of the points discussed.
(a) Problems with INFN parts
and components
-
Inspect
the bare trays for glue in the insert threads both at Plyform and at
(b) Problems with SLAC parts
and components
-
Implement
a thorough 100% testing of the studs+Nytemp before
delivery to
-
The
flight-article tie-down straps are coming in very soon and will be CMM’ed and reviewed to print.
-
SLAC
should change the torque spec for the connector mount to 0.4N-m. The present spec is dangerous.
-
-
SLAC
should check whether nest fasteners can be obtained with a locking feature
suitable for thermal/vacuum testing.
Also, the correct fastener with the button head should be sent.
(c) Electrical test issues
-
(d) Cable assembly and
bending
-
The
cable holding plate design needs to be reviewed with Martin. It appears that the cable offsets don’t work
out such that the cables line up with the connection points without
twisting.
-
INFN
wants to put some foam in place during the vibration testing to protect the
cables. Jeff will look for some suitable
foam.
-
The
tape for the cables really doesn’t work.
It is too thin and peels off very easily, and it does not fill the gap
between tray and sidewall.
-
Arthur
needs to correct the bending tools, make more copies, and make a special tool
for the uppermost cactus arm.
-
-
Steve
will check on the fit of the –x,-y corner bracket.
-
Jeff
will try to get a long (2-inch) screwdriver bit for the clip installation.
-
Jeff
will get the clip’s edges rounded over and will get Kapton tape to coat the
inner face of the clip.
(3) MCMs to return to SLAC
for inspection/rework
Luca reported that there
still is 1 MCM at G&A without 75-ohm clock-bus termination resistors. It will be returned to SLAC for rework. Also, Robert requested that all unused flight
MCMs that went to
Action Items
from Last Week:
- Arthur: write
and send out a summary of the baseplate deformation
issue.
- Arthur:
contact QA people at Nyloc.
- Jeff: get the
remaining studs dycronited
asap.
- Jeff: procure
a better socket wrench for stud installation. It needs to be longer with a
tighter fit.
- Peter: get
more extraction tools to
- Dave: set up
a meeting on the baseplate deformation issue.
- Sandro:
update the 1584 procedure with references to the new procedures.
- Dave: set up
a call-in for a G&A MRB at
- Luca: hand carry MCMs to
- Dave: get a high-level meeting going to push Parlex to perform.
- Jeff: get 10
spare square nuts for test work at Nytemp.
- Jeff:
expedite an order for new cable clips for the cable holding fixture.