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</style><article id="node-1267222" class="node node-logentry contextual-links-region article ia-n clearfix" role="article"><header class="node-header"><h1 class="node-title">
<a href="https://logbooks.jlab.org/entry/4194177" rel="bookmark">Trying to understand the recent GEM HV crate issues</a>
</h1>
</header><div class="contextual-links-wrapper"><ul class="contextual-links"><li><a href="https://logbooks.jlab.org/entry/4194177/edit?destination=email/send">Edit</a></li><li><a href="https://logbooks.jlab.org/entry/4194177/delete?destination=email/send">Delete</a></li></ul></div>
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<p class="author-datetime">
Lognumber <a href="https://logbooks.jlab.org/entry/4194177" class="lognumber" data-lognumber="4194177">4194177</a>. Submitted by <a href="https://logbooks.jlab.org/user/onl">a-onl</a> on <time datetime="2023-10-06T16:23:32-0400" pubdate="pubdate"><a href="https://logbooks.jlab.org/entries?start_date=1696620212&end_date=1696627412&book=HALOG&book=BIGBITE&book=SUPERBIGBITE">Fri, 10/06/2023 - 16:23</a></time>. </p>
<table class="field-vitals"><tr><th>Logbooks: </th><td><a href="https://logbooks.jlab.org/book/halog">HALOG</a> <a href="https://logbooks.jlab.org/book/bigbite">BIGBITE</a> <a href="https://logbooks.jlab.org/book/superbigbite">SUPERBIGBITE</a></td></tr><tr><th>Entry Makers: </th><td>hszumila</td></tr></table></div>
<div class="logentry node-content">
Saru and I were trying to understand the recent difficulties and trips in BB L0. Looking at the strip chart of the currents in detail is interesting. The top 8 channels on this strip chart are those corresponding to BB L0. We noticed that around the time there a small break in the current line (meaning it's not communicating the current readback via epics), there is an approximate corresponding current drop (severe) readout in the other GEM channels (much more significant that what we see from normal beam on/off). We do not understand the drop. The drops are on the order of a couple hundred uA and seem to happen around the same time as the blips seen in BB L0. What is also weird, is that this information is spanning 3 different power supply crates. We are suspicious because when this happened a few weeks ago, the outlet (no GEM plugged into it) also was disconnected. This time, the reason we had to access the hall to power cycle the BB L0 crate was because that outlet strip was again unresponsive as was our crate. Super odd. <br /></div>
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