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 other day I was working on a particularly difficult
electronics problem with an ion gun controller and to help figure it out, I
needed to dust off my trusty Huntron Tracker. I don’t need to use it very
often, but when needed, there is nothing better for troubleshooting electronics
problems.
Huntron Tracker
First introduced in 1979, the Huntron Tracker displays an analog signature, which is a combination of resistive, capacitive, inductive, and semi-conductive characteristics. This visual display is very helpful for comparing electronics components on a defective board. The Tracker is particularly useful for comparing components on a known defective electronics board with a known good one. The Tracker applies a tiny AC voltage to the probes so you can test components with no power applied to the board that you are testing.
Compare known good board to defective board
You can usually find defective electronics components with a DVM (digital volt meter) by testing diodes and capacitors, then measuring resistance values. But there are times when all of the individual components check out as OK with a DVM, but you know that there must be at least one defective component because the board does not work properly. For those times, the Huntron Tracker works like a champ every time. By finding some components that read differently with the Tracker, you can get a clue and ultimately, find the problem.
The early model Huntron Trackers had a little CRT display
and three power level settings. Those models are still available on EBay for
about $300.00. The Tracker that I use is one of these early ones and it still
works well.
Over the years Huntron Trackers have evolved and today’s models include more power settings, automated testing, and software. For more info visit Huntron at –
If a new Huntron Tracker is out of your price range or you can’t find an older one, there are also inexpensive curve tracer kits available on eBay that provide Tracker functionality using an oscilloscope. To find those, go to eBay and search for Curve Tracer kit.
1-30-20 I updated this blog post to include a video on how to isolate a thermally unstable electronic component using a heat gun and cool spray.
When a problem develops with your XPS or AES spectrometer and you contact RBD Instruments for assistance, we frequently hear the same question – “What could be the source of the problem?”. The troubleshooting electronics tips below may help to find out.
Most problems on XPS and AES spectrometers can be broken into two broad categories – Optics problems and electronics problems. Optics (electron optics) are parts of the system that are installed on the vacuum chamber and include things like spherical capacitive analyzers, cylindrical mirror analyzers, sputter ion guns, x-ray sources, neutralizers and so on. Electronics include units such as power supplies and controllers.
Optics can generally (but not always) easily be tested by simply measuring the resistances on the electrical feedthroughs as specified in the optic’s manual. For example, a 04-303 ion gun should have contact between pins 1 and 2 (the filament) only. All other pins should be open to each other and to ground. By open, we mean that the electrical resistance is infinite. If pin 3 were shorted to ground, we would know that the objective lens inside the ion gun has a flake that is shorting it out, and the ion gun needs to be taken apart and rebuilt. But an optic component can have correct resistances and still have a problem (such as an open contact). Sometimes a short in an optic can also cause a failure in an electronic unit.
Electronic units are the source of problems with XPS and AES spectrometers more often than optics. Most of the students who use XPS and AES spectrometers in a university environment do not have enough training or experience with electronics to really dig into the electronic circuitry, but there are still a number of simple steps that can be taken that may result in a successful repair.
First of all, make sure that all power is off to any electronic unit that you work with. Measurements of voltages should always be performed by personal who have been training to work with electronic components and (often) high voltage. Potentially lethal voltages are present in these types of systems. If you are not properly trained, do not attempt to measure voltages in electronic units.
But, as long as the power is off and the unit is unplugged, you can safely visually inspect the unit and the boards inside of the unit for obvious signs of damage. For the most part, these are indicated by discoloration of the circuit boards, melted traces, melted transistors, dried up capacitors, and burnt resistors. If you find some components that are visibly damaged, then replacing them may solve the problem. Or, there may also be additional problems and the damaged components are just a symptom.
Some things to look for include:
Heat damage to a circuit board: Discoloration of the board which indicates that a component has been running very hot.
Melted components: Transistors (the plastic type) can actually melt when overheated. This is easy to spot.
Cracked capacitors: When capacitors dry out (after say 20 years or more) they can fail. See the links below for detailed instructions on how to test a capacitor. Be careful with larger value capacitors as they can hold a charge for a long time. Just to be safe, discharge capacitors before you measure them by clipping a resistor (a few hundred to a few thousand ohms is typical) across the contacts. This is not necessary for small value low voltage capacitors.
Burnt resistors: Resistors that burn up can turn to carbon and be difficult to identify without a schematic and board layout. Measure the resistance of suspect resistors with an ohmmeter. Sometimes you need to lift one end of the resistor (desolder one end of the resistor from the board) when measuring resistors in circuit as other components that may be in parallel with the resistor can affect the reading.
Shorted diodes and transistors: You can use a DVM in the diode check mode to test diodes and transistors for shorts. See the links below for detailed instructions on how to do that.
Dullness on transistor housing: If a metal housing (cover) transistor overheats often the finish on the transistor housing may be dull as a result of overheating. You can compare the finish to other similar transistors and then use a DVM in the diode check mode to test the suspected transistor. Plastic housing transistors that have melted are readily apparent.
Below I have listed some links to troubleshooting electronics resources. If you can’t fix the problem on your older Physical electronics (PHI) electronic unit yourself after following the steps in this post, we can provide you with technical support, repair services, loaners or exchange units. Contact us for more info.
As many of you may know, RBD Instruments has been providing repair services and parts for old Physical Electronics (PHI) surface analysis systems and components for over 26 years. In fact, some of the electronic and optic units that we work on are over 45 years old!
As a result of aging electronic components in some of the very old units, or a lack of demand, we are discontinuing service on some PHI electronics and optics.
Where possible, in the list below we will offer newer alternative units as replacements. We will also offer technical support if you want to try and repair the unit yourself. With our pricing model that has a cap on the maximum labor charge for electronics and optics it is not economically viable for us to repair these really old units. And if we were to charge the actual time that it may take to repair them, then that would not make fiscal sense for you as it may be less expensive to replace it with a newer unit.
The good news is that RBD Instruments still provides repair services and parts for most older PHI surface analysis systems and components.
Here is the list of obsolete PHI units:
Electronics:
96 V/F preamplifier (We still work on the 96A and 96B)
11-010 Electron gun control (Gray faced units, we still work on the Brown faced units)
11-055 analyzer control
11-500 Analyzer control (Gray faced units, we still work on the Brown faced units)
