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Entry  Wed Dec 10 15:05:32 2014, Jenne, Update, Electronics, Xend QPD whitening board modified already IMG_1776.JPG
    Reply  Thu Dec 11 16:42:12 2014, Jenne, Update, Electronics, Xend QPD whitening board plan QPDwhiteningModification_11Dec2014.pdf
       Reply  Fri Dec 12 19:54:21 2014, Jenne, Update, Electronics, Xend QPD whitening board modified QPDwhiteningModification_XtransCompleted_12Dec2014.pdfIMG_1779.JPGQPD_Xtrans_Ytrans_12Dec2014.pdfQPD_Xtrans_Ytrans_DarkVsLock_12Dec2014.pdf
          Reply  Sat Dec 13 00:35:11 2014, rana, Update, Electronics, Xend QPD whitening board modified 
          Reply  Mon Dec 15 22:30:50 2014, Jenne, Update, Electronics, Yend QPD modified 
             Reply  Mon Dec 15 22:45:59 2014, Jenne, Update, Electronics, Yend QPD modified QPD_Ytrans_oscillating_15Dec2014.pdfQPD_IOPchannels_Ytrans_oscillating_15Dec2014.pdf
                Reply  Fri Feb 13 14:27:30 2015, ericq, Update, Electronics, Second QPD Whitening Switch enabled 
                   Reply  Fri Feb 13 14:59:13 2015, ericq, Update, Electronics, Second QPD Whitening Switch enabled 
                      Reply  Fri Feb 13 18:56:44 2015, rana, Update, Electronics, Second QPD Whitening Switch enabled 
                         Reply  Thu Feb 19 04:09:21 2015, ericq, Update, Electronics, Second QPD Whitening Switch enabled 
                   Reply  Fri Feb 13 17:07:51 2015, Jenne, Update, Electronics, Second QPD Whitening Switch enabled 
Message ID: 10782     Entry time: Thu Dec 11 16:42:12 2014     In reply to: 10774     Reply to this: 10794
Author: Jenne 
Type: Update 
Category: Electronics 
Subject: Xend QPD whitening board plan 

Here is a little PDF of what I plan to do to both of the transmission QPD whitening boards later today.  The idea is to take away the remote gain slider inputs, and force the gains to always be at +30dB.

The red and blue notes are from Koji's elog 9854, and the green are my plans for today. 

I will cut the traces from the gain slider inputs, and pull the negative input of the AD620 to ground.  The positive input will be connected to the +5 voltage line, with a divider so that the positive input to the AD620 is about 666mV. 

The AD602 will be maxed out at +30dB with anything over 625mV. 

QPDwhiteningModification_11Dec2014.pdf

Unless there are objections, I will start these modifications in an hour or so.  I will also make the Xarm whitening always-on, just like Koji has already done for the Yend.

EDIT, JCD, 12Dec2014:  These are not the modifications that were made.  Please see ____ for actual modifications.

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