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Analog Signature Analyzer Excites DUTs at 200 mV

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Breakthrough in Benchtop, In-Circuit Nondestructive Troubleshooting Mill Creek, Wash.--Huntron, the world's premier supplier of benchtop and automated in-circuit test systems, announced the introduction of the Huntron Tracker 2700 with SigAssist. The new Huntron 2700 gives test engineers and service technicians manual benchtop access to many of the testing and analysis capabilities of Huntron's popular ProTrack1 Model 20 Tracker Troubleshooting systems. With a color LCD for signature and menu display, new low-voltage test ranges, a built-in DC voltage source, dual channels, and over 100 range combinations, the Huntron Tracker 2700 lets users effectively troubleshoot the analog and digital components and circuits as well as passive devices found in the latest telecommunications, computer, IT, and military systems. The new variable 5 V DC generator lets users test SCRs, optical couplers, and other gate-fired devices in both "on" and "off" states. "We designed the new Tracker 2700 to replace the extremely popular Huntron Tracker 2000. With over 20,000 Tracker 2000s in service, the power-off, nondestructive troubleshooting capabilities of Huntron's analog signature analysis technology has proven to be an invaluable tool in the arsenal of test and service technicians worldwide," said Bill Curry, president of Huntron. "Our customers have asked us to update our Tracker technology to test the latest components and circuits. The new Tracker 2700 addresses these requirements." It has 21 selectable voltage/resistance ranges available at 5 frequencies for a total of 105 combinations of voltage, source resistance, and test frequency. This means users can troubleshoot even the most complex circuits such as switching power supplies with fail-safe protection circuits containing many passive components and solid-state devices," said Curry. Here's how the new Huntron 2700 Signature Analyzer works. With the Huntron 2700, a user applies a current-limited AC signal across two test points of a component or circuit being tested. The color LCD displays a current/voltage signature unique to the device being tested. When the displayed images are compared with known good devices (or optimally performing circuits), users can quickly determine whether the device being tested is good, bad, or marginal. Often, users refer to this as determining "the overall health" of the device being tested. The entire test procedure is completed without applying power to the device, or circuit, being tested. As a result, the risk of further damaging a device is significantly reduced. New Capabilities Make Analysis Easier New to the Tracker 2700 is Huntron's proprietary SigAssist technology. With SigAssist, the new Tracker 2700 displays real-time computed numeric values for resistance, capacitance, power, forward breakdown voltage, and reverse breakdown voltage, together with the unique current/voltage signature of the device being tested. This new capability lets users quickly select optimal ranges for testing and also analyze dynamic changes in signatures. For technicians who are not familiar with signature analysis troubleshooting, the displayed numeric data enhances their ability to learn how to use in-circuit, nondestructive signature analysis. The new Huntron Tracker 2700 comes complete with one pair of Huntron MP20 Microprobes, a set of common test leads, one blue clip lead, a power cord, and an instruction manual on CD-ROM. It retails in the U.S. for $2,595. Delivery is 4 to 6 weeks after receipt of order. Like other Huntron benchtop test equipment, the Huntron Tracker 2700 is available nationwide from an extensive network of distributors. The new Tracker 2700 is also available on-line directly from Huntron at www.huntron.com. For customers outside the U.S., CE certification is currently under way. Huntron Inc. 15720 Mill Creek Blvd. Suite 100 Mill Creek, WA 98012

Huntron is usually recognized by technicians for its power-off nondestructive Huntron Tracker instrument. Fewer engineers use Trackers, but that may change. A little history. In 1995, the company also rolled out its ProTrack series of automated repair stations. Since that time, more than 50,000 Trackers and ProTrack ATE systems have been shipped. Significantly, Tektronix inked an accord with Huntron for a Tek version of the Tracker. It was dubbed the Model TR210. That happened just three years after Huntron debuted its first Tracker. Tek's TR210 implements the ASA technology of the Tracker 2000, except that the 2000's integral monitor is supplanted by BNC connectors. Outputs are then routed to the x-y inputs of an oscilloscope. The scope is operated in the x/y mode, but the displayed signal is identical to what you'd see on an integral monitor of a Tracker 2000. Analog Signature Analysis Huntron calls its technique for locating faults analog signature analysis, or ASA. An ASA sequence involves applying a current-limited AC signal across two test points in a circuit, or across a device under test (DUT). You then vary the signal's amplitude and frequency, and the resulting display is a unique current-voltage signature. In the case of the new Model 2700, the signature is shown on the 2700's color 320 × 240 pixel LCD, permitting you to visually judge the DUT or circuit under test. Significantly, the technique is equally useful for digital and analog circuits, as well as mixed-signal boards and components. The flowchart below shows the ASA test-and-judge process. click for full-size image The applied AC signal causes vertical and horizontal deflections, with the traces forming a unique V/I signature that gives you clues to the health of your DUT. Huntron claims that the signatures can help you determine whether a component is good, bad, or even marginal. ASA signatures comprise four components—resistance (any value from an open to a short), capacitance, inductance, and what Huntron calls semi-conductance. An open circuit draws no current, so it's represented by a horizontal line on the display. On the other hand, a short would draw maximum current, and it shows up as a vertical line. Complex or composite signatures are combinations of the four basic signatures. Resistors have a constant V/I ratio, causing a linear diagonal signature, with the angle of the slope proportional to the resistance value. Capacitors and inductors cause phase-shifting, producing a Lissajous-like circle or elliptical signature that's proportional to the amount of capacitance or inductance. Capacitive signatures that flutter, vary in size, or change shape, indicate a possible problem in the dielectric. Diodes are displayed by a horizontal line that goes vertical just after the center axis of the display. Zener diodes, for example, display a so-called chair pattern that has a vertical break-over point (usually at 0.6 V), and a second break-over point at the rated voltage for the diode. Testing Chips ICs can be tested this way, too. The signatures of ICs form composite patterns called chair patterns. Typically, CMOS chips display loops in the chair patterns, and leakage current is indicated by curvature of the linear portions, and the rounding of corners, of a chair pattern. Interestingly, ICs of the same type (part number) from different vendors can be differentiated and tested using a Tracker 2700. What's more, you can include an IC maker's name in a component-type field so that you can know which company made the component if you recall your findings from storage. Significantly, you can merge the signatures of different manufacturer's ICs together, and compare results. Low Voltages Applied Unlike predecessor Tracker products, the 2700 also includes a 200 mV excitation range. It permits passive components such as resistors, capacitors, and inductors to be analyzed without turning on any sensitive parallel solid-state devices. The 200 mV signal is appropriate for 3 V logic and even lower voltage circuits. In addition to the 200 mV sine-wave excitation, the LCD-equipped Tracker 2700 can also apply 3 V, 5 V, 10 V, 15 V, or 20 V peak signals, sourcing up to 200 mA. You can also excite a circuit under test at a choice of 20 Hz, 50 Hz, 60 Hz, 200 Hz, or 2 kHz. You can also select the system's source resistance to be 10 W, 100 W, 1 kW, 10 kW, or 100 kW. A Software Boost As the press release states, the Tracker 2700 comes with what Huntron calls SigAssist technology. SigAssist lets the Tracker 2700 display real-time computed numeric values for resistance, capacitance, power, and breakdown voltage (both forward and reverse). It does this in addition to presenting the visual V/I signature. As such, SigAssist lets you more quickly select the right ranges for testing. It also helps analyze dynamic changes in signatures. Having the numeric data displayed on-screen can also ease the learning curve. The screen shot here shows a typical forward and reverse breakdown voltage signature, and calculations, for a typical zener diode The calculation occurs when the vertical portion of a signature isn't close to a short or an open. click for full-size image Not mentioned in the press release is Huntron's Workstation for Windows SigAssist software. In this PC-hosted package, SigAssist also displays numeric information based on a displayed signature, with values in ohms, farads, and watts, as well as forward and reverse breakdown voltages. It's sort of a mirror image of what you see on a Tracker 2700's LCD. But, using SigAssist, you can also open a signature window in the Workstation for Windows software and then place a cursor over the signature's image. A SigAssist pop-up then comes up. Using that, both stored and currently displayed values can be compared using color-coded Windows images. The screen shot shown shows two zeners being compared. click for full-size image If you need a simple instrument to get a handle on the basic health of a component or circuit, the new Huntron Tracker 2700 with SigAssist may fill the bill. The fact that it's not a highly sophisticated technique may be just what the doctor ordered in the hands of semi- or unskilled personnel.

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