Discussion Category:  Spectroscopy

How to change a bulb in a spec

Most specs require some "peaking" of a source after replacement.  Most specs also do some tests on power-up that require the VIS source (usually) to be at least somewhat aligned.  That being said, if your spec powered up OK and you either want to replace a weak or dead bulb, DO NOT SHUT DOWN the spec!  Turn off the sources and replace the bulb and then peak.  You stand a much better chance of successful calibration.

If your spec lets you set it to 0 wavelength (zero order), do your peaking there.  That's the first place the spec looks on power up.

Remember that your spec isn't just putting a light beam through a slit.  It is pushing a focused image of the source filament through the slit.  This means that you have to have a lamp with EXACTLY the same filament position as the OEM bulb!  Rarely will a hardware store bought bulb match.  The reason many OEM bulbs are expensive is that they physically check each and every one for filament position (I know Beckman does this).  If your VIS source has bare wire "legs" and you are not using an OEM bulb, you might need to nip a mm off each to get the bulb to sit down far enough on it's socket.

Wash all finger prints off bulbs with some alcohol!

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Asked by

Jeff V
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