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
Category Archives: General Optics and Vacuum
General information on repair, maintenance, and operation of both PHI (Physical Electronics) and other manufacturers’ systems and components
Recently, I have seen the same problem on several 32-095 and 32-096 X-ray source controls which are used on older Physical Electronics PHI X-ray photo electron spectroscopy systems.
The issue is that C9, a 680 uF electrolytic capacitor blows out and the electrolytic material leaks out on the board. Left unattended, the electrolytic etches and oxidizes the traces on the board.
If you have an older PHI XPS system that uses a 32-095 or 32-095 X-ray source control you should pull if out of the rack, remove the cover and inspect the board immediately.
If corrosion is present, then remove the board and remove C9. Note the polarity of C9 as the + indicator on the board may be etched away. Then, carefully clean the corrosion from the board as best as you can. If in the shop I use some Alconox and let it sit on the board for a while, then rinse with DI water and let the board dry overnight. In the field I have used isopropanol or methanol and cotton swabs. Note that if the traces are corroded badly then they may come off the board as you clean it. If so, you will need to use some fine copper wire to rebuild the traces.
Once the board is clean and dry, replace C9 with a new one. I will dig into this issue some more and try to determine why this problem occurs so often and come up with a permanent solution. In the meantime, I would recommend that the C9 capacitor be replaced every 5 years.
The pictures below show where C9 is located on the control board and what the corrosion looks like.
Update 5-28-23 – We tried this on two different pump set ups and it seemed to work well at first. But on one of the set ups the fine mesh O-ring became clogged with small Zeolite pieces and plugged up the line. We removed the Zeolite from that set up, the other one is working fine so far. It could be a function of the mesh size, we will continue to monitor set up #2.
Molecular sieve traps use zeolite pellets to adsorb water vapor, oil vapor and other gas molecules. They are particularly useful in preventing the back-streaming of oil vapor from the rotary vane pump into the turbo pump and vacuum chamber.
Molecular sieve oil mist trap
Molecular sieve traps are placed between the rotary vane backing pump and the turbo pump. Most molecular sieve traps also have built in heaters that are used to regenerate the zeolite once it becomes saturated with contaminants.
If you have an oil filled rotary vane pump, a molecular sieve trap is a must. However, molecular sieve traps can be relatively expensive running from $500.00 to $1,000.00 or more depending on the size.
This blog post shows a way to use existing flexible metal hose to make a molecular sieve trap for a lot less.
The general idea is to fill an existing flexible metal hose which is connected between the roughing pump and the turbo pump with zeolite pellets.
Step one is to remove the flexible metal hose.
Next, insert a mesh screen centering ring on the end of the flexible metal hose that is closest to the roughing pump. Connect the flexible metal hose to the roughing pump.
Once the flexible metal hose is filled completely (leave a little bit of room at the top) connect the flexible metal hose back to the turbo pump roughing port using another mesh screen centering ring.
Finally, label the flexible metal hose to indicate that the flexible metal hose is filled with Zeolite pellets.
That way when the flexible metal hose is removed at some point in the future who ever removes it will know that they need to remove the top of the flexible metal hose first and to empty the Zeolite pellets before removing the flexible metal hose from the roughing pump. You can also hold the bottom centering ring as the flexible metal hose is removed from the roughing pump. (That is one advantage that a regular sieve tap has is that the Zeolite pellets are contained and will not spill out when the sieve trap is removed from the backing pump).
In the experiment where I tried this idea the turbo pump and backing pump worked normally, there was no noticeable increase in the pumping time. At some point in the future when the Zeolite needs to be baked out heating tape could be used. Or the Zeolite pellets could just be replaced with new ones. Note that the volume of Zeolite pellets in the flexible metal hose is much less than what a regular sieve trap has, so the amount of adsorption would be reduced proportionally. Even so I think that this is worth considering, especially in situations where there is no existing molecular sieve trap installed.
Total cost for the two mesh screen centering rings and the Zeolite pellets was under $90.00 Finally, if you are not familiar with LDS you should check them out. They have a wide selection of vacuum related hardware at good prices and fun categories like REALLY Cheap Stuff and Surplus items. https://www.ldsvacuumshopper.com/drypumps1.html
The DGC III ion gauge controller (also called the DIG 3) used on many of the older PHI surface analysis systems can operate 2 ion gauges (only one at a time). There is a relay inside the DGC III that puts the filament current output to the ion gauge connectors on the back of the DGC III. Normally there is only one ion gauge on the vacuum chamber and it is plugged into the Ion Gauge 1 connector (normally closed) on the back of the DGC III. The relay is shown in the photo below.
DGC III filament select relay
If your DGC III does not read correctly, you can first check the +/-12V and +5V power supplies. Here is a link to some information on how to do that – DGC III power supplies test. If any of the power supplies are low and have a high AC component, then usually that issue is caused by a leaky capacitor on the power supply board. ** CAUTION! Make sure that someone who is trained on working safely with voltages up to 500V performs the voltage measurements. There are potentially lethal voltages inside the DGC III.**
If the power supplies check out OK then it is possible that the filament select relay is dirty. To test that, make sure that the DGC III is OFF and then move the black filament cable on the back of the DGC III from filament 1 to filament 2. You do not need to move the COL BNC cable as those are both tied together.
Turn the DGC III back on and press the 2 button. That will select ion gauge 2. Press the I/T 3 button to measure the vacuum and see if the DGC III works normally. If it does, then the filament select relay is dirty. You can just keep the ion gauge connected to ion gauge 2, or, you can clean the relay and connect the ion gauge back to ion gauge 1.
To clean the relay, make sure that the power is OFF to the DGC III and if not already down, pull the unit out of the rack and remove the cover.
Pull the relay out and remove the 4 screws on the bottom of the relay.
The contacts that are touching are the normally closed ion gauge 1 contacts. Use a small strip of some very fine emery cloth or sandpaper to gently clean the contacts on both sides. Then, use a small strip of paper with some isopropyl alcohol on it to remove the leftover grit. Replace the cover on the relay and reinstall the relay.
Ion gauge 1 should work properly now but if not you can order a new relay from companies like Grainger or Mouser. Just make sure that the pins match schematic that is on the side of the relay. Google 105 3PDT 10A relay and you will find it.
If your DGC III does not work and you need some help or a loaner, please contact RBD Instruments for assistance.
