Antares Analytical Tech Bulletin

May, 2003

Problem: No Burning in the MOA / FAS Sample Stand:  This month’s Tech Bulletin will deal with causes of no burring in the sample stand, other than a faulty door interlock switch which was covered in the April Tech Bulletin.

Relevant Models: MOA / FAS (all models: MOA-C …MOA-GT …. MOA- C/GT …Mil MOA), HA10/12 configured as Oil Analysis unit, older DV2 models with the Oil Analysis Module as a “2^nd stand.  Information about this problem, as it relates to Baird metal spectrometers (DV, FSQ etc) can be found in the November 2001 Antares Technical Bulletin.

Relevant Matrices: Oil and Fuel Analysis

Background Information: This Tech Bulletin will deal only with the MOA / FAS systems. Users of  HA10 / 12 or DV2 with an oil stand should contact us directly for further information.

The “source on” system for the MOA source has only a few circuits where a problem can be located, however, please remember the MOA is a very complicated analytical instrument and all circuits need to work correctly.

The Basic “Source On” Circuit:

1. When the Burn switch is pressed, a signal comes from the A&M boards  (2 large boards located on the left side of the  electronics cabinet) to send the 24 VDC which closes the K2 relay on the Relay Control Board.
2. The K2 relay closes and allows 110 VAC to pass into the AC Filter Assy RF1 (located in the MOA source) through the door interlock switch into the MOA source. How / when to suspect and troubleshoot this switch was covered last month.
3. The 110 VAC in the source closes K1 power relay (located in the MOA source).
4. The K1 power relay contacts distribute 110 VAC into the pulse & ignition circuits.

Troubleshooting the Basic Circuit “Source On”

Step 2: If the door interlock switch is good you need to isolate where the possible problem is. The quick easy way to do this:

1. Pull off the side cover of the MOA source. Use glass eye protection because of the G4T4 mercury lamp located in the source.
2. Be sure the interlock switch is pulled out (see April Tech Bulletin for explanation)
3. At the top of the source will be a blower / fan with a tube going to the auxiliary gap.
4. Standing AWAY from the source !!! push the start button to start a burn. A) If the blower starts to turn and the source does not burn, then most likely your problem is in the source or B) If the blower doesn’t turn your problem is most likely in the control / voltage circuits.

Step 3: If the blower turns & the source doesn’t fire there are 2 most likely causes:

1. The K1 Power relay has failed. WITH THE POWER OFF THE ENTIRE MOA replace this with a new K1 relay from stock. The K1 relay is located at the top middle of the source cabinet and is usually wired directly, rather than through a relay socket. Be careful because on the MOA GT there will be 2 relays in about the same location. Be sure you change the correct relay.
2. The next most likely failure (based on past experience) is the MOA Ignition transformer has failed. This is the large 23.5 KVA black ignition transformer located in the bottom of the MOA source. This ignition transformer should ONLY be tested by a qualified electrical / electronic technician with the proper test equipment. There is NO “easy” way for the average MOA operator / lab personnel to test this transformer. DON’T EVEN TRY …..

Step 4: If the blower doesn’t turn & the source doesn’t fire, then you need to look into the voltage / control circuitry. Next logical step would be to be sure the K2 relay on the Relay Source Control Board is energizing. Remember it is this relay which “turns on” the whole source.

1. Check the F6 fuse on the fuse panel. This fuse is part of the 110 VAC circuit which goes through the K2 contacts. If blown then replace with the SAME Slo-Blo fuse.
2. Check the F7 & F10 fuses. These are part of the 110 VAC “control circuitry.” Replace if blown.
3. Check the 24 VDC which energizes the K2 relay during the Burn Cycle. On the TB1 terminal strip located on the bottom front of the electronics cabinet (the BIG terminal strip). Put a voltmeter (set to the 50 VDC scale) across screws terminal 13 & 17 and push the start button. If 24 VDC (may be as low as 17-18 VDC) shows on the voltmeter there is a very good chance the K2 relay has failed. This relay is hardwired into the Relay Control Board and the best solution is to replace the whole board.
4. If there is no voltage during the Burn Cycle, there is good possibility a problem with the A&M control boards or relay driver board

If your problem isn’t found in the above, please contact Antares Analytical for more help.

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This Technical Bulletin is 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 (still under development) 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 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 results as the result of use of these Technical Bulletins, in place of service by a Qualified Service Engineer.