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2016/06/28 (Tuesday)

Previous Day

Status Tower installed up to 600mK stage, still need to install 4K stage.
0800 Begin 4K stage
East DIB1 ZC-39 Rerouting board Stripline 19 (short one)
West DIB2 ZC-13 Rerouting board Stripline 27 (long one)
SW DIB3 ZC-14 No board Stripline 20 (medium one)
0930 Note: on ZC-14 one of the two ground pins at the top is missing. On the striplines there is continuity between these two pins so this shouldn't have any impact.
1100 All three SQUETs plugged in
1130 Perform electrical check at breakout box, some problems seen…
In addition to several shorts to ground, DIB3 phB QET to QET Return lines are all Open. On all 3 DIBs, every QET-related line is shorted to Ground as well as: DIB1 phC SQUID and Feedbak lines, DIB2 phA SQUID bias/Return, DIB2 phB SQUID bias/Return, and DIB3 phA SQUID Bias/Return.
If the phB QET bias pin on DIB3's SQUET were not connect, but instead being pushed against the tower, this could cause the open connections as well as the shorts to ground. Disconnect DIB3's SQUET to see.
1215 Disconnecting the SQUET makes the shorts go away, and DIB3 phB QET → QET Return shows a connection. Plugging the SQUET back in causes the shorts to reappear and the break to return.
Removing the SQUET from Stripline 20 and measuring continuity on Pin 26 (QET B) shows that the connection is dependent on the position of the stripline. Moving it around will either break or reconnect the connection.

This is a bit of a problem. We need a rerouting board on DIB2 but that prevents us from fitting a rerouting board on DIB3. Stripline 20 was chosen for DIB3 because it's only broken wires were charge-related and there are no charge channels on DIB3. But now a phonon channel wire is broken in Stripline 20, DIB3pB = Side2pF (center). So we would have to sacrifice a phonon channel if we left off the rerouting board.

1330 Tried fitting the SQUET to DIB3 with rerouting board attached. It's true, it doesn't quite fit - the SQUET plate is tilted out somewhat, so its base is not pressed flat against the tower stage. But we'll try this anyway. Initial check shows that DIB3 pB QET bias-return is continuous again, but this may be temporary.
1500 Perform electrical check at BOB. Everything looks ok except 1) DIB3 pB QET bias wire is bad again - will certainly have to reroute it, and 2) now DIB1 pB SQUID bias-return reads 600kΩ, should be ~4kΩ. Changes a bit when stripline is touched, probably another stripline break.
1600 Check stripline continuity between DIB1 pB SQUID wires between BOB and cold end plug. Looks like Bias (pin 27) is OK but Return (pin 39) is disconnected.

Plan for rerouting Stripline 19: Bad wire = SQUID B Return. Reroute with good spare wire = QET B Return #4

  1. for SQUET-end rerouting card:
    1. add jumper from Pin 39 (SQUID B Return) to Pin 50 (QET B Return #4)
    2. break off Socket 50
  2. for D50-end rerouting card:
    1. jump Pin 18 (QET B Return #4) on the male side (stripline side) to Pin 50 (SQUID B Return) on the female side (ebox side)
    2. open switches (to break connections) corresponding to Pin 18 and Pin 50

Actually there is already a jumper on the SQUET rerouting card from 39 to 46 with the 46 socket broken off, and on the D50 rerouting card there's a jumper from 40male to 50female. This means that SQUID B Return already broke in the past and was rerouted through the QET D Ret 4 wire - so that one must have broken this time. So, follow above procedure but first remove these two jumpers.

Plan for rerouting Stripline 20: Bad wire = QET B. Reroute with good spare wire = QET D Return #1

  1. for SQUET-end rerouting card:
    1. add jumper from Pin 26 (QET B) to Pin 40 (QET D Return #1)
    2. break off Socket 40
  2. for D50-end rerouting card:
    1. jump Pin 48 (QET D Return #1) on the male side (stripline side) to Pin 49 (QET B) on the female side (ebox side)
    2. open switches (to break connections) corresponding to Pin 48 and Pin 49
D50-end stripline rerouting card switch list
U01 U02 U03 U04 U05 U06 U07 U08 U09 U10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

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