DU-640 Vis Lamp adjustment

The tool looks like a capital "L" and has a little nub at the end of the long side that allows you to move the position of the lamp left to right.  The tool is an eccentric and it does not "capture" any screw head as there are NO screws in the hole itself.  It merely moves the position of the holder by pushing against it.  Beckman service engineers had several special tools to use for this adjustment depending on the model of the spec.

Up and down is controlled by loosening the two screws and nuts of the visible lamp holder and then use a small flat blade screwdriver to adjust the position up and down.  Remember, for this adjustment you move the ceramic lamp holder OPPOSITE to which direction you want the light beam to go.  Also, small movements can result in large movements of the lamp.  Remember to turn the lamp off in between adjustments for the vertical positioning as looking into the lamp is harmful to your eyes.

Don

Josh, left to right position is simple.  Slightly loosen the tie down screw for the visible lamp and slowly move it to whatever position is required.  Like I previously stated, small movements can produce large changes in the position of the beam.  If you have a microcell holder then use that as your target.  Otherwise, a white business card is very helpful.  It is also very helpful to have a DVM attached to the detector test point on the main board.  It is a gold vertical pin near where the detector cable plugs into the board.    The voltage MUST be above 1.0 volts for you to not get light path failures at start up.  The up down position can be crucial if you areholder.a micro cellholder so take your time with that one.  As I said, do not look directly into the lamp so turn it off to make your adjustments and beware, the visible lamp gets very hot very quickly and will easily burn your fingers.  In fact, you NEVER want to touch either lamp with your bare fingers as the oils on our skin will etch onto the glass and can effect both performance AND lifetime.  Another important fact is that the focal point of the light is NOT at the front of where any cell might be at.  It is in the middle of the cell.  If you place a business card near where the detector opening is, the light pattern may appear a little diffuse but you should still be able to get decent voltage readings because even though the light is diffuse, the amount of light delivered to the detector is the same.  If you only use a standard cell holder then just position the light beam as a best fit left to right and up to down but not too high.  You really have all of the information that you need now to align the lamp but if you also replace the UV lamp, IT must be properly positioned first.

Don

Thanks to all.  Gotta go to work on this will report later

Best