RA-3 Optic Adjustment

RA-3 Optic Adjustment

This procedure should only be done at the direction of the AGS Technical Support Team, and after all other options have been exhausted.

​It is important that the Voltages are adjusted with a very clean cell and end cap glass pieces in place; adjusting the gains with a dirty flowcell will lead to additional system errors.


1.  First, you will need to remove the cover from the instrument by taking the six screws out on the back of the instrument.  With the six screws removed, you can push on the center back of the instrument while simultaneously pulling the outer chassis toward the rear and the outer cover should start to slide off.  You do not need to remove the entire cover, you just need it pulled back about 4 inches to where you can see the black optics box from the side.



2.   From the touchscreen of the instrument, open the maintenance screen and open the menu to see SIG and REF values under the A/D Converter.




3.   Open the front cover of the RA-3 and open the optic box.  Remove the Cell, carbon trap, etc. and remove the back plate, exposing the lamp housing and detectors by removing all the screws.



4.   Unplug the lamp and close the optic box and front panels of the RA-3.  The signals for SIG and REF will have dropped.

   
  It is important to close the optics box all the way back up to prevent stray light from entering during the zeroing process


5.  There is a SIG offset (the Signal offset is sometimes labeled Sample) and a REF offset hole.  They may be covered with tape.  Remove the tape after taking note of which hole is Gain (The Gain hole may say "Full") and which is offset (the Offset hole may have no marking). (see picture)



6.   Start with SIG (Sample) offset.  Using a small, NON-MAGNETIZED flathead screwdriver, rotate the screw in the sample offset hole.  Please note which direction increases and which decreases voltages.  You may need to use a flashlight to see the screw at first.

If the voltage displayed is less than 0.00, rotate the screw to increase the voltage until it becomes positive.  Once it is positive, slowly decrease the voltage until it is as close to 0.00V as possible, without going under.  If the voltage is already positive, decrease the voltage to get as close to zero as possible. This will set the zero.

7.   Repeat this process for the REF Offset

8.   With the zero set for SIG and REF, open the optic box, plug in the lamp and reassemble the cell and all pieces and then close the optics box and RA-3 doors.

9.   On the main maintenance screen, please open the service screen.  To do this, on the maintenance screen main page, press in the top left and top right corners of the touch screen in an alternating fashion until a password screen is displayed.  The password is 0219.

10. Open the I/O Test screen.  For P1, press on to activate the pump. For V2, press on to activate the pinch valve.  This will run the pump and sweep the cell.  Let the system do this for 3-5 minutes.

11. Exit out to the I/O screen and go under the voltage screen again (Maintenance Screen).  Please note SIG and REF values.

12. In the SIG Gain and REF Gain holes, please adjust the values to get as close to 4.00V as possible.

It is important that the Voltages are adjusted with a very clean cell and end cap glass pieces in place; adjusting the gains with a dirty flowcell will lead to additional system errors
.
13. Once the values are set, exit out to the main screen, push the analyzer back into the chasis and re-apply the six screws on the back and proceed as normal.

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