Technical Bulletin for February 2004

Subject:  Entrance optics solenoid, problems and solutions

Relevant Models: Baird FSQ, all DV series, all ICP (except 2070) and all HA10-12 spectrometers. Replacement parts for this Solenoid system are available through Antares Analytical for ICP, DV and FSQ models. There is no difference whether your spectrometer is equipped with the KH or HR400 source. MC20 and CMU also makes no difference.

General Background: All the above Baird spectrometers use an entrance optics solenoid to open during the expose part of the analytical cycle.

• All solenoid systems have common characteristics, though the assembly itself is different for each spectrometer.
• An entrance solenoid is used to block light, during Preburn, from entering the optical cell.
• Normally the light generated during Preburn will have 3-4 times more intensity than light generated during the expose cycle. This intense light (because of the very strong ultraviolet component) will lead to faster UV burn on the entrance mirror (where used) as well as UV burn on the grating.
• This Preburn light is not used for any measurement and serves no useful function in the day to day running of your spectrometer. Because Preburn is a normal part of the analytical cycle this light will always be present.

Problems common to all spectrometers:

• Many times failure of this solenoid will cause problems which look exactly like electronic problems, especially when analyzing samples in a Concentration mode during Routine Analysis. Most customers will automatically assume there is an electronic problem, when failure of this solenoid is the actual cause.
• When this solenoid fails, the most common problem will be all elements will show RED as being out of spec. Normally this solenoid fails at once … very seldom will it be a gradual failure
•  If the software is reporting Reference Element as a percentage, symptoms of a solenoid problem will not be immediately noticeable. If reporting as an Intensity, the Reference Intensity will usually drop to a very low number … usually less than 20 … and this will be a sign to check the entrance solenoid.
• If Reference is being reported as a percent and all elements report out of spec, then go into “Change Burn Mode” on the Menu (F9) and change Burn Mode from  Priority XX  you are running and change to Intensity … not Intensity Ratio. After closing the Burn Mode box, all numbers should change to Intensity and this will give you Reference Intensity.
• If this is seen during an analysis, the entrance solenoid should be the 1^st thing checked, before going into the electronics or power supplies. It is also one of the easiest things to check, especially in the DV series of spectrometers and usually the last thing customers check. All that is required is to remove the triangular top cover behind the sample stand and check for proper operation. If the solenoid opens during expose and you are still getting “:Out of Spec” messages … then the solenoid isn’t your problem.
• When the solenoid fails, no light is let into the spectrometer, thus no reference or element intensities to be measured, thus elements show “Out of Spec.”
• NOTE:  It is possible for a solenoid to open part way. When this happens, normal Standardization Factors & Offsets will make large differences from the last time you Standardized.. When drastic change in Factors 

& Offsets happens, especially when they happen at once, a partially opening solenoid should be one of the things checked … but this is not the only cause for this problem.

DV 1 to 5 Series, All ICP (except 2070):  The earlier DV models used a 110 VAC electric solenoid which has the solenoid arm attached to the shutter shaft. The shutter itself is located under the solenoid, inside the entrance optics chamber.

• This solenoid is opened only during expose by a signal coming from the spectrometer interface board.
• Because this particular solenoid is a glorified magnet / shaft assembly, normally it is the relay on the spectrometer interface board, or MC20 / CMU control board which has failed.
• This particular assembly uses a spring to “ force” the shutter shaft closed after expose cycle is completed and power is taken off the solenoid. Over time this spring can weaken, thus allowing the solenoid to stay open (partially or fully) during Preburn … causing rapid UV burning of the entrance mirror.
• This can be solved by gently removing the solenoid and spring, stretching slightly and reinstalling. If this “stretching” is done, the opening / closing action of the solenoid needs to be checked before operating the spectrometer. Stretching this spring to much can stop the solenoid from opening the shutter.
• When reinstalling the solenoid onto it’s mount, care should also be taken when tightening the solenoid nut itself. It is possible to tighten to much and this will cause a “binding” of the solenoid … stopping it from opening during expose. Again the action should be checked prior to using the spectrometer.

DV6 and DV6E:  The DV6 uses an argon operated solenoid to open the shutter shaft.

·         This argon operated solenoid is directly connected to the shutter shaft and no return spring is used. The return spring is located in the solenoid itself and no adjustment can be done by the operator.

·         The gas (argon) pressure is adjusted by a needle valve down on the DV6 gas panel and normally needs no adjustment by the operator.

·         The argon is supplied  to the solenoid by a small gas relay on the gas panel, which operates during expose. The control voltage for this electric relay is generated from the Universal Fiber Optic cable.

·         Both the argon solenoid on the entrance optics and the argon solenoid / relay on the gas control panel have been known to fail periodically.

FSQ:  The FSQ Entrance solenoid is more difficult to get at and replace because of the FSQ entrance optics design.

• The entrance optics solenoid is a 110 VAC solenoid opened with a signal from the FSQ interface board (UFO board for FSQ with an HR400 source).
• FSQ solenoid is more liable to “bind” and leave the shutter open, though this does not happen very often. This problem is usually caused by a movement of one of the collar nuts used on the shutter shaft.
• Unlike the DV / ICP shutter shafts which are mounted vertically, the FSQ shutter shaft is mounted horizontal.
• If problems are suspected on the FSQ, the 1^st thing is to listen for the sound of the shutter opening during expose. With the stand door open, begin a burn and between Preburn & expose a distinctive CLICK will be heard from the top of the sample stand. This sound is the shutter opening. Though this sound is a good indication, it’s best to actually look at ht e shutter itself for correct operation.
1. Turn off the source
2. Remove the black U shaped stand door support (mounted between top & bottom sample stand doors).
3. Remove the silver sample block / counter electrode holder as a unit
4. Take out the sample stand slide.
5. On the black plastic sample block mount will be a small oval shaped aperture (hole). This aperture is where the light burned during sample analysis enters the entrance optics.
6. Using a small flashlight shine light into the aperture and you should see only black. This is the shutter itself.
7. If reflected light is seen then it’s very possible you have a solenoid which is binding and is only closing partially. This must be solved before going any further so please contact Antares Analytical for further help.
8. Start a burn while looking into the aperture (hole) with the flashlight. During the Flush / Preburn portion of the sample analysis nothing should be seen. During expose this shutter should open fully and you will see light reflected back from the entrance mirror. At the end of the expose portion, the shutter will close and reflected light will not be seen.
9. Assuming all the above is correct your entrance solenoid / shutter assembly is not the problem.
10. DANGER: Before going any further with repairs, please contact Antares Analytical for more help. Repairing the FSQ entrance solenoid requires unbolting and moving the sample stand. Moving the sample stand will cause loss of optical alignment. THIS IS GAURANTEED TO HAPPEN.  
11. We must provide complete instructions for unbolting and installing the sample stand, otherwise optical alignment can (and probably will be) lost making the spectrometer unusable and requiring a Service Call by a qualified Service Engineer to correct it.

If help with the above problems, or any problems with your Baird spectrometer, please contact Antares Analytical for further assistance.

This Technical Bulletin is written and / or edited by Gerry Smith, Technical Services Manager of Antares Analytical. Having spent 25 years working with Baird spectrometers (22 years with Baird Analytical in various capacities, including many years as Final Test / Calibration Manager and Senior Service Engineer, International Operations) he or any of our Technical Support Staff, are well qualified to answer any Technical or Applications problems you may have.

For further information or access to past monthly Technical Bulletins covering a variety of subjects, please  visit our website at www.antaresanalytical.com .For more information, to be added to this list,  or help with other subjects including Tech Support, spare & replacement parts, or on-site Service by qualified Baird trained Antares Analytical Service Engineers, please contact us at info@antaresanalytical.com 

This bulletin is meant for informational purposes only and it not meant as a substitute for Service performed by a qualified Service Engineer. Any use of this information is done strictly at the discretion of the user. Antares Analytical is not responsible for any misfortune which happens as the result of use of these Technical Bulletins, in place of service by a Qualified Service Engineer.