Research Gases for Laboratories

Posted on May 26, 2021 by Randy

Laboratory gases are readily available in large cylinders from companies such as Airgas, Norco and local welding supply companies.

But for small quantities of gases or specialty gases used in vacuum optics such as UV sources and Ion guns, it may make more fiscal sense to use lecture bottles instead of the larger size gas cylinders which are commonly found in laboratories.

Lecture bottles are small compressed gas cylinders that are typically 12-18 inches long and 2 to 3 inches in diameter.

They hold approximately 2 cubic feet of gas and are pressurized to as much as 1800 PSI. High pressure gas cylinders require a regulator to step the pressure down. The pressure required for the application will determine which regulator is needed. For example, the Varian variable leak valve used on many 04-303 ion sources can take a maximum pressure of 500 PSI. However, it is recommended that the argon gas pressure be set to 15 to 25 PSI for best results.

Since lecture bottles are small, it costs less to ship them. But most importantly, when you buy a lecture bottle you are buying the bottle as well as the gas. Full sized cylinders are generally rented for a monthly fee in addition to the cost of the gas and delivery. Factoring in the monthly rental fee for the cylinder, a lecture bottle could be much less expensive over time. Especially for optics like UV sources where you may only use it a few times a year.

In the US, Matheson provides a wide assortment of specialty gases in lecture bottles. Matheson also has a worldwide distribution network.

https://www.mathesongas.com/gases

Ultra-high purity gases have 5 nines (99.999%) purity and Research grade gases have 6 nines (99.9999%) purity.

Another provider in the US that carries Lecture bottles is Advanced Specialty Gases –

https://www.advancedspecialtygases.com/PureGas.html

In Europe, Messer can provide gases in small cylinders:

https://www.messergroup.com/

https://www.messer.de/spezialgase

In the UK, CK Gas Products provides a variety of gases in lecture bottles:

http://www.ckgas.com/lecture-bottles/

Gas regulators are available from these companies as well as from Grainger. Be sure to specify the type of connection on the gas bottle when you order it and also to order the correct connection on the regulator. For best results, insert a valve between the regular and the outlet line. Finally, you also will need to pump out the line and regulator before opening the gas bottle as otherwise your gas will become contaminated with air.

Testing the fuses on the Card Rack power supply outputs

Posted on May 10, 2021 by Randy

The fuse strip located near the hinge on the OEM supply door routes the +5, +15, and -15 voltages from the OEM supply to the card rack unit motherboards.

Each card rack unit has a dedicated section of fuse strip and specific fuse values.

When troubleshooting problems with card rack units it may be necessary to test the fuses in the fuse strip. With the card rack power OFF you can visually inspect each fuse to see if any of them look like they are blown. You can also use an ohmmeter to measure the resistance of the fuses (typically one ohm or less). In some cases it is helpful to measure the actual voltage on the fuses. It is possible that a fuse that looks good is actually blown. Or the voltage on the fuse may be loading down on the output side.

Since the +5, +15, and -15V OEM supply outputs are floating with respect to ground, you need to reference your meter to the correct place in order to measure the voltage. The card rack power needs to be ON when measuring the voltages on both sides of the fuses. The voltage should be very close to the same value on both sides of the fuses. One side is voltage in, the other side is voltage out to the card rack unit.

The picture below shows the correct OEM supply reference point for the +5V, -15V, and +15V fuses.

For example, to measure the middle section -15V fuse you would need to put your DVM red lead on the left side of the middle fuse, and the black lead of your DVM to the CH3 white wires on the OEM supply. Then also measure the other side of the same fuse. The voltage on both sides of the fuse should be very close (within a few millivolts). Note that you may need to remove the protective plastic cover on the fuses in order to be able to measure the fuses.

There are up to 13 sections on the fuse strip and each section is typically dedicated to a particular card rack unit motherboard. Keep in mind though that the fuse locations are not written in stone and so units on your system may be plugged into other fuse sections. Also, some units are removed when an RBD software upgrade is installed. When in doubt, trace the power cables from the back of the motherboard to the fuse strip.

The fuse values (in Amps) and locations are shown below:

5400 XPS

Section	Unit	Top +5V	Middle -15V	Bottom +15V
1	72-488	10	–	–
2	71-205	5	5	2
3	72-250	3	1	1
4	72-490	10	5	5
5	72-030	1	1	5
6	Not used
7	Not used
8	80-360	5	5	5
9	77-067	2	2	10
10	72-360	1	–	1
11	Terminator	1	–	–
12	Not used
13	Not used

5600 XPS

Section	Unit	Top +5V	Middle -15V	Bottom +15V
1	72-366	1	1	1
2	80-365/366	5	5	5
3	72-030	1	1	5
4	71-205	1	2	1
5	72-488	10	–	–
6	74-500	10	–	–
7	MCD Preamp	1	–	1
8	81-175 or 73-080	10	2	2
9	74-062	10	–	–
10	97 or 72-100	1	2	5
11	73-070 or 73-080	5	2	2
12	73-057	3	3	3
13	72-700	1	1	1

650 / 660 AES

Section	Unit	Top +5V	Middle -15V	Bottom +15V
1	79-170 or 81-175	10	2	2
2	74-062	10	–	–
3	72-150 / 96A	5	5	5
4	74-500 / Term	10	0	0
5	Not used
6	Not used
7	AES 72-100 / Term	3	2	5
8	97 SED / 72-100	1	2	5
9	Not used
10	72-105	1	2	1
11	72-600	2	1	1
12	73-057 / Term	3	3	3
13	77-072	5	2	2

Here is an example: Lets say you want to measure the voltage on the 80-365 fuses on a 5600 XPS system. You would first locate the correct fuse section, in this case that is section 2. The top fuse in section 2 is the +5V supply and so you would measure from the left side of the top fuse in section 2 to the white ground wire on Channel 1 (the big lugs) on the OEM supply. Then you would also check the other side of the same fuse to make sure that you have the same voltage on both sides of the fuse. The middle fuse in section 2 is the – 15V fuse and it is referenced to the white wires on Channel 3 on the OEM supply. Finally, the bottom fuse is the +15V and it is referenced to the white wires on Channel 2 of the OEM supply.

By using the correct reference point you can easily measure the voltages on both sides of the card rack fuses when troubleshooting electronic problems with your older PHI XPS or AES system. As always, refer servicing to qualified personnel. The OEM fuse voltages are considered low voltage. However, most of the card rack units themselves generate high voltages and should be only worked on by technicians with the proper training to work safely with high voltage. If you need help troubleshooting a problem with your XPS or AES system, contact RBD Instruments for assistance.

11-065 Ion Gun Controller Emission Switch Operation

Posted on May 6, 2021 by Randy

The emission scale switch on the 11-065 ion gun control is used to change the scale of the emission to three levels: 100% (X1), 10%(X.1) and 1%(X.01). The effect of changing the emission switch is to reduce the emission current, which in turn reduces the ionization (pressure reading) and ion (target) current proportionally.

Initially, the emission needs to be set to 25mA in the X 1 scale and the leak valve is adjusted to achieve 15 to 25 mpA of pressure.

Adjust Argon to get 15 t0 25 mPa of gas pressure

The graph below shows the target current vs. time and the effect of changing the emission current from X 1 to the X.1 and X.01 scales.

When changing the emission scale switch, the emission reading on the 11-065 front panel meter will not change, but the actual emission current will be reduced by a factor of 10 (X.1 scale ) or 100 (X .01 scale). So for example if the emission is set to 25 and the emission scale switch is changed to X .1, the meter still indicates 25mA but the actual emission is 25mA X .1 = 2.5mA. The pressure display will be reduced by a factor of 10 as well since the number of ions being generated are reduced proportionally to the emission current. Ideally, the target current will also be reduced by to 10% of the X1 value when the emission scale switch is changed to X.1. In the graph above we see that the target current drops from about 4.25uA to .8uA as the emission drops from 25mA to 2.5mA. As expected, the target current drops a factor of 10ish to 70 nA as the emission scale switch is changed to the X .01 position.

The picture below shows that the pressure drops to about 2mPa as the emission scale is changed to X.1

This picture shows the pressure dropping to .2mPa as the emission scale switch is changed to the X.01 position.

The emission scale switch is an easy way to reduce the ion target current by a factor of 10 or 100 in order to achieve lower sputter rates.

Note that Balzers RVG 050 thermovalve controllers cannot be used on older 11-065s in the X .1 or X .01 emission scale positions since they depend on the pressure reading for feedback. Newer 11-065s have a circuit that compensates so that the pressure output is correct at each emission scale setting.

11-065 LAS1515 regulator note.

The +15V LAS1515 regulator that is on the heatsink (second from the front) can be marginal. The symptom is that the emission current is unstable, or it becomes stable after the 11-065 warms up.

The SCC brand of LAS1515 regulators has inconsistencies. When measuring the waveforms between the two pins using the Huntron Tracker, 50% of the LAS1515s presented like a diode, the other 50% presented like a Z. The Z is correct. In addition, even the Z pattern SSC brand LAS1515 regulators did not perform properly. Either the emission instability happened right away, or it would happen once the 11-065 warmed up.

The solution was to replace the SSC brand LAS1515s with the NTE equivalent NTE1916 regulator. That worked fine.

RBD TechSpot

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Research Gases for Laboratories

Testing the fuses on the Card Rack power supply outputs

11-065 Ion Gun Controller Emission Switch Operation