Tag Archives: scanning auger

How to test a 97 SED preamplifier

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Older PHI scanning auger systems use the model 97 SED preamplifier to obtain secondary electron images. Occasionally you will not be able to get a TV image on your scanning auger system but are not sure what the problem is. This post will explain how to test the 97 SED preamplifier to determine if it is working properly or not.

For purposes of this test, we will run the J3 video output from the 97 SED preamplifier directly to the TV monitor video input. If you have a 660 or 4300 scanning auger system where the image is displayed directly on the PC monitor you can leave the J3 cable connected.

  1. Turn off the 32-100 electron multiplier supply main power. For 660 and 4300 systems, turn off the card rack power.
  2. Disconnect the J1 NEG and J2 POS cables from the 97 SED preamplifier. That will remove the high voltage from the preamplifier and ensure that there is no risk if electrical shock.
  3. Carefully remove the 97 SED preamplifier from the SED feedthrough flange. Hold the 97 SED preamplifier firmly when loosening the screws and lift the preamplifier straight up and off of the SED flange so that you do not risk breaking the ceramic feedthroughs on the SED flange.
  4. Remove the J3 video out cable and connect a BNC cable from J3 video out on the 97 SED preamplifier to the Video In on the back of the TV monitor. If you have a 660 or 4300 scanning auger system, disregard this step.
  5. Note the position of the COL tab on the 97 SED preamplifier as shown in the pictures below.
  6. Turn on the 32-100 electron multiplier supply or card rack power supply.
  7. Make sure that the 32-100 SED voltage is turned to OFF and the SED voltage knob is fully CCW. On 660 or 4300 systems, after going through the turn on sequence set the SED voltage to Zero in the scanning dialog box.
  8. Use a wire or screwdriver and “tickle” the COL tab on the 97 SED preamplifier.
  9. When tickling the 97 SED COL tab you should see a significant amount of noise on the TV monitor. If so, then the 97 SED preamplifier is working properly. There could be contrast or gain issues with the preamplifier that may not show up with this test, but essentially you can rule out the 97 SED preamplifier as the reason that you are not getting a TV image.

 

Additional information:

On 660 and 4300 systems this test may be inconclusive as the 79-170 or 81-175 scanning electronics may have a problem on the video board.  If you do not see noise in the TV dialog box when performing this test then you can monitor the J3 video output on the 97 SED preamplifier and except to see what appears as high frequency noise in the range of 0 to +2V DC when the 97 SED preamplifier COL lead is being tickled.

If the 97 SED preamplifier test passes but you are not getting a TV image there are a few other possibilities.

  1. No TV raster. An easy way to test that is to acquire an elastic peak in the point mode and then turn on the TV with a low magnification. The elastic peak should become jagged if the TV raster is working properly. You can also use an oscilloscope and measure the waveforms on the end of the CMA deflection cable.
  2. No SED voltage. You can use a high voltage probe and measure the voltage between the NEG and POS cables that connect to the 97 SED preamplifier.  CAUTION – high voltage is present! Refer this test to qualified personnel who are trained to work with high voltage. 
  3. A defective or worn out electron multiplier. If you have a megohmmeter that can measure over 100 Meg ohms (many meters can only measure resistance to 20 Meg ohms) you can measure the resistance between the NEG and POS feedthrough on the SED flange. Typical resistance for a good electron multiplier is 80 to 120 Meg ohms.  If the resistance is 150 Meg ohms or higher the electron multiplier should be replaced.
  4. Use care when remounting the 97 SED preamplifier to the SED flange as the SED feedthroughs can be easily broken. Make sure the 32-100 or card rack power supply is OFF when reinstalling the 97 SED preamplifier or cables.

RBD Instruments provides repair services and loaners for the 97 SED preamplifier, and we also provide the electron multipliers. If you need help diagnosing problems your system or parts, please visit our website at rbdinstruments dot com.

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Lab6 filament replacement procedure

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This procedure shows the steps to replace the Lab6 filament in the 25-120A CMA used in the Physical Electronics 600 and 660 scanning auger systems.

First, vent the system. Here is a link to a procedure on how to do that: 600_System_Up-to-air_Procedure

  1. Remove the filament cap on the top of the analyzer. Do not unscrew the cable! Remove the 3 screws as shown in the picture below and then lift the cap up and off of the analyzer filament ceramic.
  2. Remove the twenty 5/16″ bolts that hold the filament flange to the CMA. Those may be 1/2 ” hex head or 12 point cap head bolts.
  3. Tilt the filament flange back on the hinge.
  4. Use gloves and a clean straight blade screwdriver to loosen the 4 filament screws as shown in the picture below.
  5. Remove the 4 filament screws and carefully lift up and remove the whenelt cap. The filament is mounted inside the whenelt cap.
  6. Install the new filament making sure that the filament legs line up with the filament contact tabs.
  7. Hold the filament down while you install and tighten the 4 filament screws.
  8. Install a new 8″ copper gasket and gently tilt the filament housing back onto the analyzer.
  9. Tighten the bolts (use anti seize compound if the bolts are dry) and then
  10. Pump the system down.

Although it is recommended that the system is baked out where ever it is up to air, baking may not be necessary if the system is back filled with dry nitrogen and given a few days for the vacuum to recover. If you install the new filament on a Friday and let the system pump over the weekend, then the vacuum will likely recover into the low 10-9 Torr range without a bake out.

To condition the new filament, slowly (over a period of an hour or more)  bring up the filament current to a starting value of 1.3 amps at 3 kV beam voltage and see if you can get sufficient emission current and target current. If so, then you can operate the filament with 1.3 amps of filament current. You may need to use oxygen to rejuvenate the filament if the emission does not come right up. Here is a link to a tech tip on how to thoroughly characterize the new filament if you want to really dial it in: imaging procedure for 600 and 660

RBD Instruments provides the Lab6 filaments used in the Physical Electronics 600 and 660 scanning auger analyzers.

Scanning Auger Objective Coil Replacement Procedure

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This post describes the steps needed to successfully replace the objective coil on PHI 600 and 660 systems. Note: Use gloves, clean tools and place UHV aluminum foil on your workspace. For best results, dust off the assemblies with dry nitrogen or canned air as you reassemble the analyzer to remove any dust particles.

Tools required:

Latex gloves

Wrenches

Small screwdrivers

Tweezers and/or needle nose pliers

048-4 Bristol spline wrench

Disassembly Procedure

  1. Vent the system.
  2. Remove the filament housing (8″ flange on a hinge).
  3. Stand the analyzer on the back of the condenser nipple (8″ flange).
  4. Remove magnetic shield (4 screws).
  5. Remove conical ceramic (4 screws, aluminum ring).
  6. Remove the outer cylinder after first disconnecting the VM screw.
  7. Remove the upper inner cylinder assembly (4 screws). Be very careful not to touch the grids.
  8. Remove the 8 screws that hold the two aluminum rings in place and carefully lift up the Objective lens assembly. Scribe the objective lens assembly so that you can put it back with the exact same orientation.
  9. Turn the Objective lens housing upside down and remove the 8 screws that hold the nose cap in place.
  10. Hold the cap and point the lens assembly up and carefully lift the nose cap off.
  11. Carefully lift off the octopole ceramic and spacers. TIP: Position the spacers on the clean aluminum foil in the order in which you remove them so that you can replace them in the same order later.
  12. Remove the 3 flat spring couplers and ceramics from the objective coil wires. You will need a 0.048 4-spline wrench.
  13. Loosen and remove the 4 nuts which hold the objective coil to the base plate.
  14. Remove the objective coil. Note that there are 4 spacers on the studs.

Reassembly Procedure:

  1. Install the spacers on the objective coil studs and insert the objective coil into the base.
  2. Put the nuts on the studs and tighten the nuts finger tight.
  3. Using some 0.020 wire, slip it in and around the coil and the center tube so that the coil is evenly spaced around the center tube.
  4. Securely tighten the 4 nuts.
  5. Slide the ceramics over the objective wires and replace the 3 objective coil spring couplers.
  6. Stack up the octopole ceramic spacers and slide the octopole ceramic back on. It is keyed and can only go on one way.
  7. Carefully slide down the nose cap and replace the 8 screws finger tight.
  8. Slightly rotate the nose cap to make sure that the octopole ceramic is well seated and then tighten the 8 screws.
  9. Reinstall the objective lens assembly into the inner cylinder. It can only go in one way and still make the electrical connections.
  10. Install the two aluminum rings in place and tighten the 8 screws.
  11. Measure the resistance of the condenser and objective connectors and make sure that you have a good connection to the objective lens. The resistance on the two internal windings of the objective coil (Pins A, B and C) should be about 8 Ω each and 16 Ω across.
  12. Check for connectivity on pins A, B, C, D, E, F, G and H on the octopole deflection feedthrough to the octopole ceramic to ensure that you have a good contact on each plate. The best way to do this is to set your meter up so that it beeps with continuity and then insert a small (0.010) wire into the nose cap and move it around while having the other end of the meter connected to the octopole defection feedthrough. If the connections do not all check out then remove the objective lens assembly and look for a contact problem.
  13. Reinstall the upper inner cylinder assembly. (Do not touch the grids!)
  14. Install the outer cylinder and reattach the VM wire.
  15. Carefully place the conical ceramic on top of the outer cylinder and measure the resistance of the outer cylinder to ground. It should be 3 MΩ. If the conical ceramic is not making good contact, the resistance will be about 6 MΩ. It needs to be 3 MΩ. Shim with copper or gold foil if necessary. The resistance coating section (the dark sections between the rings) on the conical ceramic should be 180 degrees out from the resistance coating on the base.
  16. Replace the aluminum ring on top of the conical ceramic and tighten the 4 screws evenly and firmly (but not too tight!).
  17. Reinstall the magnetic shield.
  18. Degauss the analyzer.
  19. Ohm-out the objective connector one more time, and also ohm-out the VM to ground to ensure that the resistances are still correct.
  20. Use a new gasket and reinstall the CMA into the bell jar.
  21. Pump down the system and bake-out.

The pictures below will help you to understand this procedure.

RBD Instruments provides replacement objective coils for the PHI 600 and 660 scanning Auger systems. Contact us for more information. The coils are expensive but we occasionally have used coils that cost much less than a new one.

Additional information on the 25-120A CMA is posted below the pictures.

 

25-120A Analyzer Info

1. Resistance measurements:

  • Cond. coil, pins D & E, 10 ohms
  • Obj. coils, pins A, B, & C, 8 ohms, 16 ohms, open to ground

2. Steering – all pins open to ground

  • Cond. X: A & C, gnd at J
  • Cond. Y: B & D, gnd at M
  • Obj. X: E & G, gnd at L
  • Obj. Y: F & H, gnd at K

 20-622 System Test

It is possible for a 20-620 or 20-622 to work on the bench but not focus properly on a system. That is because on the bench the Objective and ISO Objective supplies are tested separately but on the system the objective coil is actually two coils which are tied together. It is possible for one of the objective supplies to cave in when connected to the objective coil. You can do a quick test by measuring the voltage across the current resistors behind the front panel of the 20-622 or 20-620.

Voltages for the 20-622 are listed below. The 20-620 should show a similar trend.

20-622 3kV Beam voltage, COND set to 35%, OBJ set to 74.49%, and Objective fine pot set to midrange. COND .856 V DC
OBJ 3.68  V DC
ISO OBJ 3.69  V DC