====steps for changing lamp====
  * In one excel sheet, note down current gain of all filters of ErbaXL 640 from maintenance menu.
  * Take out sealed unused lamp from Preventive Maintenance kit of ErbaXL 640.
  * Keep hands away from glass   part of new halogen lamp. Make sure that there is no crack or breakage in the glass part.
  * Make sure that gas does not have been leaked.
  * Note down ideal gain value given in note provided with new lamp box in same excel sheet. 
  * Now switch off the instrument first.
  * Remove reaction tray cover of the instrument.
  * Remove inner cover of Reaction Tray(RCT) by loosening the attached screws.
  * 2 flange like wires attached with old lamp are attached with the 2 screws seen in that area(see below picture) and by following wires you can see a lamp in box like structure(see below picture).
  * First by loosening the screws remove the wires and then using smallest L shaped key (present in tool box) loose the screw over the box covering lamp. DO NOT REMOVE SCREW FULLY.
  * Now remove the lamp and preserve it in box with proper labelling(not to be used).
  * Take new lamp. A slot is present on lamp which should be facing upward while inserting lamp in the box(see below picture) 
  * Tighten the screw over the box using same L shaped key. 
  * Fix the flange like wires in those screws by tightening screws.
  * Close both covers properly and check alignment.
  * Now start the instrument and check for light path. Go to SERVICE CHECK⇒RCT TRAY⇒OFFSET. Check the two cuvette lightening and compare their equal brightness.
  * Start the AUTOSPAN and note down gain of all filters in the sheet of previous gain.
  * Run the quality controls for atleast 5 times in that batch and one time for next 3 to 4 batch and run the patients samples only after correct control results.
  * Make sheet of comparision of ideal gain(mentioned in the note present in new lamp packing) and gain before and after changing lamp. Upload the sheet in LIS in Equipment record.