AIDA
GELINA
BRIKEN
nToF
CRIB
ISOLDE
CIRCE
nTOFCapture
DESPEC
DTAS
EDI_PSA
179Ta
CARME
StellarModelling
DCF
K40
DESPEC
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Entry time:
Thu Oct 21 16:18:51 2021
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During investigations into the noise today by NH and OH a couple of findings were made on the grounding of the FEEs and Adaptor boards. - The adaptor boards have no connection to the FEE ground over the ERNI connector - Currently we are providing one via a ground cable between the FEE Al cooling and the Lemo ground on the adaptor board - The Al cooling plate is not electrically isolated from the copper plate on the ASIC and both are connected to the electrical ground on the FEE - Verified with 0 resistance between plate and HDMI ground shield - The FEE is electrically isolated from the frame but when cabling is connected they show 0 resistance - With electrics disconnected but water still connected they show 200kOhm - With the bias core going to FEE14 and the braid going to FEE8 better performance in FEE14 is obtained by disconnecting FEE8 adaptor board from the ground - The cost of this is the rate of FEE8 goes up to 300k - It is essential to have the adaptor board ground on the FEE ground but unsure why having both adaptor boards connected to their respective grounds makes one worse - The resistance between all FEEs is not zero. Some show a 5Ohm and some show a 35Ohm resistance between each other
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