Author Archives: Randy

74-500 DASH motherboard contact issue

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The 74-500 DASH (data acquisition system hardware) is used on PHI 5600 to 5800 XPS systems and comprises two circuit boards to count the MCD preamp signals. Those boards plug into a motherboard which in turn is connected to power supplies and the PC.

The DASH motherboard has connectors on both sides of the board and so it can not be flow soldered on both sides of the board. To get around that issue the motherboard was designed using square pins on the 96 pin connectors which fit tightly into some round pads on the board. The corners of the square pins make electrical contact with the pads.

Over a long period of time (20 plus years) oxidation can buildup on the square pins which result in poor electrical contact between the pins and the pads.

The result can be unstable operation of the DASH that can show up at unstable data, wide peaks and overflow count rates (over 20 million CPS).

The fix for this contact issue is to solder the pins to the pads by hand. There are a total of 576 pins that need to be soldered, it takes some time to do.

The pictures below show the back of the DASH mother board and the pins before and after soldering.

Remove the two little break out board and then solder all the pins. Clean off the flux after soldering all the pins.

Replace the breakout boards after soldering and cleaning the board. If your MCD or DASH issue is related to the DASH mother board pin contacts, soldering all of the pins on the 96 pin connectors will solve the problem.

For more information about troubleshooting count issues with the PHI 5600 to 5800 XPS systems contact RBD Instruments.

16-020 heat exchanger 12″ deionizer cartridge issue

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The 16-020 heat exchangers are used with the older Physical Electronics (PHI) 5100 through 5400 X-ray photo-electron spectrometer (XPS) systems.The 16-020 has a built-in deionizer cartridge (and a particle filter) which keeps the water in the closed loop system clean and it also keeps the resistance of the water high. 

The original deionizer cartridges were blue and had a recess in the bottom of the filter that matched up with a plastic guide on the bottom of the Millipore housing.  Those blue deionizer cartridges are no longer available. The new replacement deionizer cartridges do not have a recess on the bottom.

When a new deionizer cartridge is used with the original Millipore housing the plastic guide on the bottom of the housing will push up on the bottom of the deionizer.  This makes it difficult if not impossible to fully screw on the housing.  It also puts pressure on the bottom of the deionizer cartridge which can rupture the bottom of the deionizer and cause the media particles to leak out, potentially causing an issue with the water flow and or damage the pump and lead to a catastrophic anode melt down. There are two ways to solve this fit issue. One is to cut and grind out the top part of the guide on the original Millipore housing. To do that you need to remove the plug on the bottom of the housing and then use a drill or cutting wheel that is mounted on a drill extension. The pictures below show a housing before and after modification.

 

The other option is to replace the original Millipore housing with new housing that correctly fits the new deionizer cartridge. But if you replace the housing you will also need to replace the manifold as the new manifold will not fit into the original Millipore manifold.

RBD Instruments provides both deionizer cartridges and housings. If you have the original Millipore housing on your 12” deionizer cartridge then I recommend that you inspect it to see whether the guide on the bottom has been cut down or not.  If not, you should cut it down or replace the housing.  

If the deionizer is ruptured then the entire cooling system (reservoir, pump, water lines and source) needs to be inspected and flushed out.This problem is an issue only with the 12″ deionizer cartridge on the 16-020 heat exchangers. 

The 16-050 heat exchanger that is used on the 5600 and up XPS systems has a 10″ deionizer cartridge.

Not sure if you need to replace your deionizer cartridge?  Just run up the high voltage on your X-ray source to 15kV but do not set an power to the X-ray source.   Observe the emission current reading on the HV supply.  If the deionizer is good the reading will be 1-2 mA.  Once the leakage current gets up to 3-4 mA at 15kV you should plan on replacing the deionizer cartridge and particle filter soon.  If the leakage current at 15kV is 5 mA or higher you should replace the deionizer and particle filter and also flush out the water with new distilled water from a grocery store.  Lab distilled water does not always work but grocery store distilled water works every time.

Contact RBD Instruments to order the deionizer and particle filter.

Ion gauge coated ceramics

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Ion gauges work by using a hot tungsten filament to ionize gas molecules and then collect the ion current and convert that current to a reading in Torr, Pascal or millibar.

Over time the ceramics on the ion gauge feedthrough can become coated with tungsten or titanium. That coating is conductive and when the coating covers the entire length of the feedthrough then the resulting leakage current can affect the accuracy of the ion gauge or prevent it from working at all. The picture below shows an example of a coated ion gauge.

Usually once the ceramics are fully coated then the ion gauge needs to be replaced at a cost of $500.00 or more.

This blog post will show you how to remove the coating from the ceramics and restore normal operation of the ion gauge for about $15.00

The first thing that you will need to do is to buy some dental polishing tape.  I used some TDV diamond strips as shown below. You can get diamond polishing tape on Amazon.

With the filaments removed from the ion gauge, mount the ion gauge in a vise.  The ion gauge needs to be tight but not so tight that the flange warps.

Use the diamond strip in a back-and-forth motion to remove the coating from the ceramic.  Use a light touch as you want to remove the coating but not eat away at the ceramic any more than necessary.

Once you have the ceramic cleaned off, use a soft paint brush to clean the grid and to remove any small bits of ceramic from the flange. Note that all of the deposition does not need to be removed, but you want enough so that there is a gap on the ceramics which will eliminate any leakage current. The picture below shows the results after a few minutes of cleaning. Not very pretty, bit it does restore functionality.

Install a new filament set and you are good to go!  RBD Instruments sells ion gauge filaments for the PHI DGCIII controller.  Contact us for more information.