Table of Contents
2010/11/13
| 0045 | Stopped pumping dewar at 4.6E-5 mbar (after approximately 24 hours). |
|---|---|
| Start evacuating IVC. | |
| Take SQUET card ZC-70 to clean room for electrical check (work conducted on clean bench) - looks fine. | |
| 0200 | Stop evacuating IVC at 4.6E-5 mbar and transfer N2 gas before opening. |
| 0700 | Cleaned flanges. Installed SQUET card ZC-70 and conducted electrical check. |
| Found QET A, B, C & D and QET return lines grounded. | |
| Multimeter exhibited strange behaviour - reading 2 MOhms initially, followed by 300 Ohms after changing scale to manual. | |
| Changing scale back to automatic has no effect - multimeter reads approximately 300 Ohms for each grounded pin | |
| 0800 | Perhaps breakout box is at fault… check ebox connector. |
| Same result, the above pins are grounded. There is a short somewhere. | |
| 0900 | Checked pin 2 to ground on SQUET card ZC-70: |
| While ZC-23 is plugged in, multimeter reads 300 Ohms. | |
| While ZC-23 is unplugged, multimeter reads open. | |
| Weird result. | |
| Ebox connectors - unlikely for both to fail simultaneously and fault seems to lie further down the chain. | |
| Striplines - again unlikely for both to fail simultaneously and fault seems to lie further down the chain. | |
| SQUET cards - possible, but unlikely as electrical check at room temperature has been conducted on both cards. | |
| Tower - most likely. Although electrical check has been performed at room temperature, something might have gone wrong during installation. Next step is to conduct tower level continuity check. | |
| Broken multimeter - I wish! Doubtful, but worst comes to worst, can always take one from clean room for comparison. |
Tower Level Continuity Checks
| Detector | G41 | DIB1 | ||
|---|---|---|---|---|
| side coax | 1 (ZB1-1-6) | date/who: | 2010/11/13 | HC |
| face | ||||
| +lead | - lead | signal | typical | measured |
| 1 | 2 | QET A | 100 to 200 | 140 Ohms |
| 1 | 3 | QETA-B | 100 to 200 | 227 Ohms |
| 3 | 4 | QET B | 100 to 200 | 145 Ohms |
| 3 | 5 | QETB-C | 100 to 200 | 299 Ohms |
| 5 | 6 | QET C | 100 to 200 | 246 Ohms |
| 5 | 7 | QETC-D | 100 to 200 | 288 Ohms |
| 7 | 8 | QET D | 100 to 200 | 160 Ohms |
| 7 | 1 | QETD-A | 100 to 200 | 247 Ohms |
| 9 | chassis | LED1 Rforward | 9M | open |
| chassis | 9 | LED1 Rreverse | <1nS | OK |
| 10 | chassis | LED2 Rforward | 9M | open |
| chassis | 10 | LED2 Rreverse | <1nS | OK |
| 1 | 11 | Qo Rbias | 24nS to 26nS | 26 nS |
| 11 | 12 | Qo C coupling | <1nS | OK |
| 12 | 13 | Qo Rfeedback | 24nS to 26nS | 26 nS |
| 1 | 13 | <1nS | OK | |
| 1 | 14 | 24nS to 26nS | 26 nS | |
| 14 | 15 | Qi C coupling | <1nS | OK |
| 15 | 16 | Qi Rfeedback | 24nS to 26nS | 26 nS |
| Short to chassis | All signal except LEDs | <1nS | OK | |
| Detector | G41 | DIB2 | ||
|---|---|---|---|---|
| side coax | 1 (ZB1-1-9) | date/who: | 2010/11/13 | HC |
| face | ||||
| +lead | - lead | signal | typical | measured |
| 1 | 2 | QET A | 100 to 200 | 145 Ohms |
| 1 | 3 | QETA-B | 100 to 200 | 302 Ohms |
| 3 | 4 | QET B | 100 to 200 | 273 Ohms |
| 3 | 5 | QETB-C | 100 to 200 | 375 Ohms |
| 5 | 6 | QET C | 100 to 200 | 250 Ohms |
| 5 | 7 | QETC-D | 100 to 200 | 294 Ohms |
| 7 | 8 | QET D | 100 to 200 | 232 Ohms |
| 7 | 1 | QETD-A | 100 to 200 | 226 Ohms |
| 9 | chassis | LED1 Rforward | 9M | 0.8 MOhms |
| chassis | 9 | LED1 Rreverse | <1nS | OK |
| 10 | chassis | LED2 Rforward | 9M | 0.8 MOhms |
| chassis | 10 | LED2 Rreverse | <1nS | OK |
| 1 | 11 | Qo Rbias | 24nS to 26nS | 26 nS |
| 11 | 12 | Qo C coupling | <1nS | OK |
| 12 | 13 | Qo Rfeedback | 24nS to 26nS | 26 nS |
| 1 | 13 | <1nS | OK | |
| 1 | 14 | 24nS to 26nS | 26 nS | |
| 14 | 15 | Qi C coupling | <1nS | OK |
| 15 | 16 | Qi Rfeedback | 24nS to 26nS | 26 nS |
| Short to chassis | All signal except LEDs | <1nS | OK | |
| 1200 | Compare with previous results. |
|---|---|
| Everything seems fine apart from LEDs… one problem at a time. | |
| 1230 | Phone call from Vuk. Two possible reasons: |
| 1. IR shields are causing shorting. Easy to test: remove IR shields and insert both SQUET cards. | |
| 2. One QET bias or QET feedback pin is shorting. As Ge conducts at room temperature, one short to ground will cause another short between all QET bias and QET feedback lines - most likely cause as we have never used either SQUET card in a run. Only way to tell for sure is to test each of these pins to ground for both SQUET cards. | |
| 1250 | Quick test to see if IR shields are to blame comes out negative. |
| From previous measurements, ZC-23 seems to be responsible for the short to ground. This is quickly confirmed by unplugging it: no short to ground. SQUET card ZC-23 taken to clean room for further checks. | |
| 1330 | Can't find short to ground on ZC-23. |
| 1354 | With the cold end of the stripline open, found QET return C (Pin 25 of breakout box, Pin 13 of Stripline D50, Pin 4 of P1) is shorted to ground. The resistance between breakout box Pin25 and ground is 5.8 Ohm; the resistance between Pin 13 of Stripline D50 and ground is 3.2 Ohm; the resistance between Pin 4 of P1 and ground is 33.7 Ohm. There is a short at the warm end on trace 19. The total length of stripline is 110“, the short is about 10” from the warm end. |
| 1612 | Opened ebox connector flange but didn't find the short. We don't know what happened. Sealed the ebox again and no shorts found. |
| 1848 | All thermometer check out OK at room temperature |
| 2025 | Start pumping IVC |