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<DIV><SPAN class=358495421-14052007><FONT face=Arial color=#0000ff
size=2>Hermes,</FONT></SPAN></DIV>
<DIV><SPAN class=358495421-14052007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=358495421-14052007><FONT face=Arial color=#0000ff
size=2>Definitely you should always power down the centrifuge before the
slit assembly is removed! Yes I believe photomultipliers can show some slow
recovery after excessive light exposure, but if the intensity has not recovered
by now I don't think it will without intervention, and y<SPAN
class=358495421-14052007><FONT face=Arial color=#0000ff size=2>ou will probably
need to bring in the service engineer.</FONT></SPAN></FONT></SPAN></DIV>
<DIV><SPAN class=358495421-14052007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN><SPAN class=358495421-14052007><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=358495421-14052007><FONT face=Arial color=#0000ff
size=2>However it is possible that the problem is not in the PMT
itself. The intensity loss might have been caused by the
attempted cleaning of the slit assembly---it is very easy to block the slit
itself with debris, or possibly you did not put the two little lenses back in
quite correctly. Also my understanding is that there is an integrated circuit
amplifier located within the base of the PMT housing, and this too can be
damaged if there is excessive PMT current (too much light). So unfortunately you
might need an entire PMT assembly, not just a new PMT.</FONT></SPAN></DIV>
<DIV><SPAN class=358495421-14052007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=358495421-14052007><FONT face=Arial color=#0000ff size=2>Good
luck,</FONT></SPAN></DIV>
<DIV><SPAN class=358495421-14052007><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=358495421-14052007><FONT face=Arial color=#0000ff
size=2>John</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><FONT
face=Tahoma size=2>-----Original Message-----<BR><B>From:</B>
rasmb-bounces@rasmb.bbri.org [mailto:rasmb-bounces@rasmb.bbri.org] <B>On
Behalf Of </B>Hermes Reyes Caballero<BR><B>Sent:</B> Saturday, May 12, 2007
8:05 AM<BR><B>To:</B> rasmb@rasmb.bbri.org<BR><B>Subject:</B> [RASMB] max out
photomultiplier<BR><BR></FONT></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Dear RASMB
members,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I was cleaning the slit ensemble
in the XL-A and I though of cleaning the PMT too. So I did it with ethanol and
expose the PMT to the light when the machine was turn on. I read somewhere in
this forum that can cause the PMT to max out, and in fact the intensity was
around 6-fold lower than before the cleaning procedure. I turn off the machine
for 12 hrs and the intensity is still very low, with no apparent recovery.
Does anybody know if this PMT will comeback? <o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Have a nice
day!!<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><st1:Sn w:st="on"><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Hermes</SPAN></FONT></st1:Sn><FONT
face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><st2:PersonName w:st="on"><st1:GivenName w:st="on"><FONT
face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Hermes</SPAN></FONT></st1:GivenName><FONT
face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <st1:Sn
w:st="on">Reyes_Caballero</st1:Sn> <st1:nameSuffix
w:st="on">PhD.</st1:nameSuffix></SPAN></FONT></st2:PersonName><FONT face=Arial
size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
Candidate<BR><STRONG><B><FONT face=Arial><SPAN style="FONT-FAMILY: Arial">The
Giedroc Lab</SPAN></FONT></B></STRONG><B><SPAN
style="FONT-WEIGHT: bold"><BR></SPAN></B>Department of Biochemistry &
Biophysics<BR><st2:place w:st="on"><st2:PlaceName
w:st="on">Texas</st2:PlaceName> <st2:PlaceName
w:st="on">A&M</st2:PlaceName> <st2:PlaceType
w:st="on">University</st2:PlaceType></st2:place><BR>2128 TAMU Room
419<BR><st2:place w:st="on"><st2:City w:st="on">College Station</st2:City>,
<st2:State w:st="on">Texas</st2:State> <st2:PostalCode
w:st="on">77843-2128</st2:PostalCode></st2:place><BR>Phone: (979)
845-6828</SPAN></FONT><o:p></o:p></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> </SPAN><o:p></o:p></FONT></P>
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