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Hi All,</div>
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This is probably related to the dark room DC power supply issue Bobby corrected Monday. You can actually see a similar offset on the Humidity sensors.</div>
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While investigating the recent breaker trips, we discovered that one of the laptop-style DC power bricks (24 VDC) used inside the dark room was wired in parallel with the PLC DC power supply (24 VDC). On Monday morning, Bobby isolated the power supplies, which
seems to have caused an offset in the excitation voltage for the environment sensors and/or an offset in the signal voltage that goes back to the PLC. </div>
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Bobby is investigating.</div>
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Thanks,</div>
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Josh<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Halld <halld-bounces@jlab.org> on behalf of Alexander Somov via Halld <halld@jlab.org><br>
<b>Sent:</b> Tuesday, February 25, 2025 4:40 PM<br>
<b>To:</b> halld@jlab.org <halld@jlab.org>; Timothy Whitlatch <whitey@jlab.org><br>
<b>Subject:</b> Re: [Halld] PSS testing</font>
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Thanks, Tim.</div>
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I was just concerned about a potential light leak (though it’s likely not the case), as we currently can’t enter the room to check.</div>
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Cheers,<br>
Sasha</div>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Alexander Somov <somov@jlab.org><br>
<b>Sent:</b> Tuesday, February 25, 2025 4:07 PM<br>
<b>To:</b> halld@jlab.org <halld@jlab.org>; Timothy Whitlatch <whitey@jlab.org><br>
<b>Subject:</b> Re: PSS testing</font>
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Hi Tim,</div>
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Will the Hall will be reopening today ?</div>
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Also, could you confirm if the light sensors inside the dark room were recalibrated? The readings are currently between 0.45 and 0.49, whereas they were around 0.25 yesterday. I’m hoping there isn’t any light in the dark room.</div>
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Thanks,</div>
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Sasha</div>
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<div id="x_x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Halld <halld-bounces@jlab.org> on behalf of Timothy Whitlatch via Halld <halld@jlab.org><br>
<b>Sent:</b> Tuesday, February 25, 2025 3:12 PM<br>
<b>To:</b> halld@jlab.org <halld@jlab.org><br>
<b>Subject:</b> [Halld] PSS testing</font>
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We just found out that the hall is closing now for PSS testing for a few hours.</div>
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Sorry for the late notice</div>
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Timothy Whitlatch, PE State of Virginia</div>
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Hall D Chief Engineer</div>
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Jefferson Lab</div>
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757-876-1766</div>
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