A blog on the repair, operation and calibration of surface analysis systems and components including electron spectrometers, sputter ion guns and vacuum related hardware. Click on the Index tab below to see a list of all posts. Visit our website at http://www.rbdinstruments.com
The model 32-100 electron multiplier supply is used on older Physical Electronics Auger electron spectroscopy and X-ray photoelectron spectroscopy surface analysis systems to control the electron multiplier voltage.
When using the 32-100 electron multiplier supply in the digital mode (the software automatically sets the electron multiplier voltage) the auto-ems box in the Auger Scan software AES electron multiplier properties dialog box needs to be checked, and the CMA multiplier switch on the front panel of the 32-100 must be set to digital.
But what if the 32-100 still does not work in the digital mode? In that case, there may be a problem with one of the digital ICs. The following procedure explains how to try and repair this problem.
Turn off the 32-100 and remove the cover.
Most 32-100s have three ICs for the SED digital side of the control which are not used. You can move those ICs over to the CMA side of the control and see if that solves the problem.
Remove ICs U2, U4 and U6. These are the CMA digital ICs. Then, move over U3, U5 and U7 from the SED side if those chips are available. If they are missing, then you will need to order some of those ICs from Digikey, Newark or RBD Instruments. U2 and U4 are 74LS174s and U6 is an AD7521.
If you did have those ICs and that did not solve the problem, then it most likely means that one of the encoder circuit ICs are defective. Those are U16 (74123) and U1 (AM25LS2538). RBD Instruments provides these parts.
You do not need to replace the SED digital ICs as they are not used.
It is assumed that the 32-100 is working in the analog mode. If the 32-100 is not working in the analog mode it will not work in the digital mode either.
Refer to the pictures below for the locations of the ICs on the 32-100 motherboard.
Note that the switch positions need to be set as shown below.
32100-switch-positions
If you need further help troubleshooting your 32-100 electron multiplier supply please contact RBD Instruments dot com
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.
Turn off the 32-100 electron multiplier supply main power. For 660 and 4300 systems, turn off the card rack power.
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.
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.
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.
Note the position of the COL tab on the 97 SED preamplifier as shown in the pictures below.
Turn on the 32-100 electron multiplier supply or card rack power supply.
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.
Use a wire or screwdriver and “tickle” the COL tab on the 97 SED preamplifier.
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.
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.
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.
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.
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.
This post will explain how to test and replace the nude ion gauge filament assembly on a Physical Electronic (PHI) X-ray photoelectron, Auger electron or SIMS system. Look at the pictures at the bottom of the post before you read the procedures.
Background – On most PHI surface analysis systems the ion gauge filament is located either above the table tops in back of the vacuum chamber, or just under the tabletops. The newer (as in less than 30 years old) systems have a cover that protects the user from the exposed electrical connections to the ion gauge pins. On the oldest PHI systems the ion gauge pins are exposed, but located under the table tops and difficult to access (and so relatively safe).
Here are links to some videos that explain how an ion gauge works –
Turn off the DGCIII (or other brand of) ion gauge control. This is not only the first step; it is the most important step! Ion gauge controls such as the DGCIII used on older PHI systems have about 200 volts of DC on the grid. If you do not turn off the DGCIII (or other) ion gauge control before removing the wires to the ion gauge you will likely receive a potentially lethal electrical shock. If you are not familiar with working safely with electricity then refer this procedure to qualified personnel. Or, turn off the DGCIII and also and also unplug the 120 VAC power cord on the back of the DGCIII and then there is no danger of electrical shock.
Loosen the set screws on the shield retaining collar. Do not loosen or remove the bolts that connect the ion gauge to the system! See the pictures at the bottom of this post for clarification.
Loosen the strain relief screws and slide the shield out and away from the ion gauge, being careful to support the wires.
Using an 048-4 spline wrench, loosen the ion gauge coupler set screws by turning the set screws closest to the flange CCW 1 to 2 turns and then gently pulling the coupler and wires off of the ion gauge pins. TIP: As you remove the couplers turn the set screws CW 1 turn so that they do not fall out of the couplers. RBD provides the 048-4 spline wrench and the setscrews.
Use an ohmmeter and measure the resistance between the center filament pin (common) to the outside two filament pins. See the picture below. The pins resemble a smiley face and the filaments are the smile. The grid is the eyes (some ion gauges have 2 grid pins, some only one), and the collector is the center pin (nose). The filament resistances should be 1 ohm or less when measured from the center filament post to the outside two filament post. If a filament is burnt out (open) then the resistance will be infinite or some high value if there is a tungsten coating on the filament base.
If one filament is burnt out but the other one is good, then you can switch filaments. If you have 3 wires connected to the filaments then swap the outside two filament connectors. If you have just two filament wires, then move the outside filament wire to the other side.
If both filaments are open, then the filaments need to be replaced. See the replacement procedure in the following section.
ion-gauge-wire-connectionsHow to replace the ion gauge filaments:
Vent the chamber.
If not already done, remove the connectors from the ion gauge as per the previous procedure.
Remove the bolts from the ion gauge flange.
Remove the shield retaining collar.
Carefully remove the ion gauge.
Loosen the top set screws on the 3 filament base connectors. These are typically .050 hex screws.
Remove the old filament assembly.
Install the new filament assembly and tighten the set screws. Make sure that the filaments are parallel with the grid.
Use a new copper gasket and place the ion gauge up to the flange. Make sure that the filaments are facing down. They will not line up perfectly parallel, so just choose the best position where the bolt holes line up. By facing the filaments down you will prevent any debris from falling onto the grid which may short out and damage the ion gauge control.
Place the shield retaining ring up next to the ion gauge flange and rotate it so that the set screws in the shield retaining ring are accessible.
Insert the bolts and tighten the flange.
Reattach the ion gauge couplers. Make sure that the pins are bent slightly in towards the center collector wire so that none of the pins will short to the shield when it is installed.
Carefully slide the shield over the wires and press the shield firmly into the shield retaining collar.
Tighten the shield retaining set screws.
Slightly tighten the strain relief screws.
That’s it! Pump the system down and the ion gauge is ready to turn on once you get into the 10-4 Torr or better vacuum.
RBD Instruments provides replacement filament assemblies, complete ion gauge assemblies and the required spline and Allen wrenches. Contact us for more information.
