jeffrey.kissel@LIGO.ORG - posted 18:06, Tuesday 23 January 2018 - last comment - 18:06, Tuesday 23 January 2018(40237)
ZM2 Electronics Status Update -- ZM2 portion of US SatAmp is Busted
J. Kissel, M. Pirello FRS Ticket 9771 (EDITED -- we confused ourselves: it's the US SatAmp that isn't reading out ZM2 correctly, not SUS-SQ-21 cable as originally suspected) After identifying and fixed that ZM2's HAM-A driver has not been properly jumpered (see LHO aLOG 40218), we still are chasing down why we see so little ADC voltage from the OSEM sensors, and why the OSEM spectrum looks so poor in performance. After playing the "swap the cable connections with a known working chain at every connection of the whole chain" game, we traced the problem down tothe cable between the SatAmp and Chamber feedthrough; SUS-SQ-21the US SatAmp reading out the ZM2 OSEM chain (see wiring diagram here D1700384).The nail on the coffin is attached: we read out ZM2 from the chamber feedthrough with the OFI's ex-vacuo cabling (its equivalent "last cable on the way to the chamber" is SUS-SQ-30) and electronics -- and vice versa -- we see full, normal levels of ~15000 [ADC ct] of DC OSEM sensor voltage on the three OSEMs that the OFI digital system can read out, and we see low, junky DC OSEM sensor voltages on the three OFI OSEMs.Throw thatcableSatAmp in the trash, I say!
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The ASCII art version of the two SUS's wiring diagram:
--------+ +----+ +----+ +----+ +-----+
ZM2 | SUS-SQ-21 | | SUS-SQ-23 | | SUS-SQ-28 | | SUS-SQ-10 | |
in |-----------| |-----------| CD |-----------| AI |-------------| DAC |
Chamber | | | |____| |____| |_____|
| (A) (B) | | (C) (E) (F) (G) (I) (K)
________| | SA |
| |
| | SUS-SQ-25 +----+ SUS-HAM5-89 +-----+
| |----------------------------| AA |-------------| ADC |
|____| |____| |_____|
(D) (H) (J) (L)
--------+ +----+ +----+ +----+ +-----+
OFI | SUS-SQ-30 | | SUS-SQ-31 | | SUS-SQ-33 | | SUS-SQ-35 | |
in |-----------| |-----------| CD |-----------| AI |-------------| DAC |
Chamber | | | |____| |____| |_____|
| (A) (B) | | (C) (E) (F) (G) (I) (K)
________| | SA |
| | SUS-SQ-32 +----+ SUS-SQ-11 +-----+
| |----------------------------| AA |-------------| ADC |
|____| |____| |_____|
(D) (H) (J) (L)
Description of tests:
(0) Starting conditions: wiring as drawn above.
OFI read is read out well (~15k cts at ADC), ZM2 is read out poorly (~1k cts at ADC).
(1) Swap ZM2 21 (A) with OFI 30 (A) (at the chamber).
Result: OFI signal chain (starting with OFI 30 (A)) is reading out ZM2, and does so well. ZM2 signal chain is reading out OFI (starting with ZM2 21 (A)), and does so poorly.
Conclusion: Something is bad with something in ZM2 signal chain. ZM2 in chamber is OK.
(2) Go to starting conditions, but swap ZM2 21 (B) with OFI 30 (B) (at the back of the SatAmp).
Result: OFI is readout poorly by ZM2 signal chain, ZM2 is readout well by OFI signal chain.
Conclusion: Begin to rule out something is bad with SUS-SQ-21, and suspect SatAmp or upstream.
(3) Go to starting conditions, but replace ZM2 SUS-SQ-21 entirely with a temporary cable.
Result: ZM2 signal chain still reads out ZM2 poorly.
Conclusion: Something is bad upstream of SUS-SQ-21, or temporary cable is bad.
(4) Go to starting conditions, but replace OFI SUS-SQ-30 entirely with same temporary cable
Result: OFI signal chain reads out OFI well.
Conclusion: Temporary cable is good. Must be Something is bad upstream of SUS-SQ-21.
(5) Go to starting conditions, but swap ZM2 25 (D) with OFI 32 (D) (at the front of the SatAmp).
Result: ZM2 25 (D) and upstream reads out OFI SatAmp and downstream well.
Conclusion: ZM2 Signal chain from SUS-SQ-25 connection at SatAmp works well, must be that SatAmp is busted.
Grand Conclusion -- SatAmp is busted.
*phew*
#SlowAndSteadyWinsTheRace
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After an additional test of swapping the ZM2 and OFI signals through another nearby, vacant chassis -- that for the VOPO H1H2H3V3 OSEMs (i.e. 21 (B) and 30 (B) into the back of the VOPO chassis, and 25 (D) and 32 (D) to the front of the new VOPO chassis), which resulted in *both* signal chains reading out poorly, Marc pulled the chassis to look inside -- suspicious of a similar jumper problem discovered recently with the ZM2 HAM-A coil driver chassis (see LHO aLOG 40218) He discovered that none of these new SatAmps had jumpers in place over the JP1 "AOSEM vs. BOSEM" connector (see first page of "AdL 4 Channel Satellite Amplifier" D080276). Sheesh! Of course, only as I write this aLOG to I realize that I told Marc that he should jumper the JP1 connector in the AOSEM configuration, but HTTSs use BOSEMs. Doh!@ I've taken transfer functions and an amplitude spectral density of the OSEMs. All look strikingly normal now. Wahoo! I wonder... the OM1 reference looks pretty much dead on with the new "fixed" ZM2 TFs. Are all the US sat-amps reading out BOSEMs jumpered to AOSEM? I confess I don't know the difference between the response of the two, and clearly a BOSEM works well jumpered to the AOSEM position (i.e. ZM2). I'll talk with Marc tomorrow and test ZM2 with the SatAmp jumpered to the BOSEM configuration to see what happens.
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