Что такое asa using a curve tracer
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Что такое asa using a curve tracer

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Сurve tracer Assist-ASA

Curve tracer Assist-ASA

Curve tracer of voltmeter and impedance signatures Assist-ASA is a hardware-software complex designed for technical diagnosis and troubleshooting in electronic digital, digital-to-analogue and analogue circuits, modules and units using parametric method.

Assist-ASA has the possibility of troubleshooting (of microchips, transistors, capacitors, resistors etc.) on the board of unit under testing (here and after – UUT) without supplying it with feeding voltage.

Curve tracer can be used by staff without high qualification. It also provide conditions to make a repair of electronic modules quickly even if basic circuit diagrams are absent or not found.

Troubleshooting of UUT is performed with parametric method VI (UI, ASA) by measuring volt-ampere signatures and impedance characteristic in the check points of the malfunctioning electronic module and then compare data to the reference points.

Reference characteristics are measure on known-good circuit and are stored in files in PC. There is also a possibility to work without storing the reference data (using and applying the second probe in the same point on known-good board).

Assist-ASA operates with the characteristics presented in the form of graphical signatures and their corresponding numerical values (R is resistance, C is capacitance, U is voltage at the inflection point of the current-voltage characteristic). The criterion for the discrepancy of characteristics during automatic comparison is the excess of the threshold of tolerance of the measured R, C, U from the reference one. The threshold is set programmatically in percentage terms. For most cases, it is recommended to set the value of the limit deviation threshold at the level of 10–15%.

The method allows you to get information in order to determine the faulty elements on the board as well as to find breaks and short circuits of the conductors of the printed circuit board.

The Assist-ASA consists of an analysis unit and two active probes (each of them is equipped with a contact needle and a micro-circuit). The USB analysis unit is connected to a control computer (laptop) with special software installed. Assist-ASA can be equipped with optional accessories.

Characteristic tracer has a range of advantages in comparison with its analogues:

— two channels and two modes of signature comparison (comparison to reference data and comparison to known-good module of the same type) on one screen;

— high level of automation during creation of signature data base;

— automatic identification of the quality of the contact of the probe’s needle with the board;

— automatic use of three different combinations of parameters of the probe signal during the measuring of the each signature;

— automatic identification of signatures correspondence with producing sound signal;

— the criterion of signatures correspondence is managed from the interface;

— one channel (measuring the current signature, recording it to a file, comparing the current signature with the reference one from the file);

— two channels (comparing the current signature with the signature of the known-good UUT)

from 5 Ohm to 10 MOhm,

with the discreteness 1Ohm (in the range from 5Ohm to 1 kOhm), 100 Ohm (5kOhm – 1 MOhm), 100kOhm (1MOhm – 10 MOhm)

from 2 pF to 1000 mkF,

with the discreteness 1 pF (in the range from 2 pF to 1 mkF), 1000 pF (1 mkF – 1000 mkF)

— analysis unit «Assist ASA»

— two active probes with markings

— set of maintenance documents

Launched the release of a new model of curve tracer Assist-ASA

Curve tracer of voltmeter and impedance signatures Assist-ASA is a hardware-software complex designed for technical diagnosis and troubleshooting in electronic digital, digital-to-analogue and analogue circuits, modules and units using parametric method.

Assist-ASA has the possibility of troubleshooting (of microchips, transistors, capacitors, resistors etc.) on the board of unit under testing (here and after – UUT) without supplying it with feeding voltage.

Curve tracer can be used by staff without high qualification. It also provide conditions to make a repair of electronic modules quickly even if basic circuit diagrams are absent or not found.

Troubleshooting of UUT is performed with parametric method VI (UI, ASA) by measuring volt-ampere signatures and impedance characteristic in the check points of the malfunctioning electronic module and then compare data to the reference points.

Reference characteristics are measure on known-good circuit and are stored in files in PC. There is also a possibility to work without storing the reference data (using and applying the second probe in the same point on known-good board).

Assist-ASA operates with the characteristics presented in the form of graphical signatures and their corresponding numerical values (R is resistance, C is capacitance, U is voltage at the inflection point of the current-voltage characteristic). The criterion for the discrepancy of characteristics during automatic comparison is the excess of the threshold of tolerance of the measured R, C, U from the reference one. The threshold is set programmatically in percentage terms. For most cases, it is recommended to set the value of the limit deviation threshold at the level of 10–15%.

V-I Tester (aka ASA or Octopus or curve tracer)

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I want to build a simple V-I tester and based on this article (or this) I did this easy circuit: R1 = 560Ω
R2 = 100Ω
R3 = 1kΩ
where R1 and R2 is a voltage divider to set the \$V_<(DUT+V_)>=1VAC\$ and R3 limit the current in the Device Under Test. I used this transformer, with 6.3V, 10 VA output (is dual, but I use only one output). My question:

  1. If I change the voltage divider resistors to \$R_1=56Ω\$ and \$R_2= 10Ω\$ (especially), isn’t better? With 10Ω I will reduce the output impedance of the circuit that feed the DUT, thus I don’t load the source because it is in parallel to the \$R_3+R_\ge1000Ω\$ and then \$R_3+R_\gg R_1\$ , isn’t?
    BTW the current I draw is \$I =\frac\approx 100mA\$ and the output power is at the «safe» value of: \$6.3V\cdot100mA = 0.63VA\$
  2. With this voltage divider I have a voltage less than 1VAC across the DUT. The article says that I can test also Diode, Zener, etc. How is possible with this small voltage?

33.9k 33 33 gold badges 145 145 silver badges 265 265 bronze badges
asked Apr 21, 2022 at 15:09
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\$\begingroup\$ Just to say that R3 «limit» the current through device, but is also the «measure» sensor of this current. Point 2: diodes need only 0.7V . current is always «exp», and the scale doesn’t matter. You can’t determine the Zener point if the voltage is too low. \$\endgroup\$

Apr 21, 2022 at 17:15

\$\begingroup\$ Point 1: changing values is not really useful, because R3 limits the current. NB: adding a battery, one pot, and one resistor to control current, should also be used for testing and tracing curves of quasi any type of «transistor» . \$\endgroup\$

Apr 22, 2022 at 7:09

\$\begingroup\$ @Circuitfantasist — Divider R1- «R2 variable» only to limit the excursion of max voltage on DUT (some kind of current protection). For low current, it is enough and easy through R2. For high currents, a variable transformer (or a «fast» triangular voltage pulse with a low duty cycle) should be needed to adjust the voltage applied on DUT (as on a professional Curves-tracer), but with a scheme of «power» protection (so the calculation of v*i on the DUT is necessary to remain under Pmax) . \$\endgroup\$

Apr 22, 2022 at 18:19

\$\begingroup\$ @Circuitfantasist It is a very good exercise in a lab and helps to understand some drawing functions (mathematical with scope) and electronic characteristics of DUT. This simple circuit is very useful. I used this simple curve tracer about 55 years ago with my «own scope made» . and a professional tool Philips (radiomuseum.org/r/philips_transistor_curve_tracer_pm_6507.html) 5 years later at university. \$\endgroup\$

Apr 22, 2022 at 19:56

\$\begingroup\$ Right. I forget that the axes for the «tunnel» curve are reversed! I used only the load line for the curves of UJT (V vs i) . 🙁 \$\endgroup\$

Doesn’t a curve tracer harm modern circuits?

I’ve read about a thing called a «curve tracer» that you can use to compare known good circuits with bad circuits. It consists of an AC voltage with a resistor that sweeps from -5 to +5V (or similar) and reads the voltage and current going to the component to plot a XY graph. The resulting graph will be the «signature» of the component. Below is the basic circuit that makes this work: And here are some example graphs: Image source (both) This is all nice, neat and easy to build, but my question is: While you can hook up a simple LED or capacitor and get a nice graph out of it, won’t any modern IC be damaged if you put -5V (AC) through its VCC rail, even if low current, considering that most ICs have a very low reverse voltage maximum rating. I saw a couple of videos of people testing and making whole databases from a single board, but isn’t that playing russian roulette, in a way? In the motto of: «Let’s put AC through until something breaks?» EDIT: There are some commercial devices that rely on this principle, for example the «UCE-CT220S». Of course it’s much more sophisticated, but it still relies on passing AC through a component that could be sensible. Thanks for any help in advance!

Fusseldieb
asked May 18, 2021 at 12:55
Fusseldieb Fusseldieb
381 2 2 silver badges 12 12 bronze badges

\$\begingroup\$ The source link says 1V at 1mA. The resistor values back that up. Also note most cmos chips have protection diodes on the i/o pins. \$\endgroup\$

May 18, 2021 at 13:07

\$\begingroup\$ Note that some components require special care. Such as tantalum capacitors — 10µA current in reverse can destroy them. I’d say that a curve tracer is used for testing known components, in a known way, for expected results (not blindly testing every component on a board to build a «database.») \$\endgroup\$

May 18, 2021 at 13:15

\$\begingroup\$ As someone who uses a «curve tracer» with +/- 100V channels, you can absolutely destroy components if you configure it incorrectly. At the same time, I can also configure mine as needed so that I don’t (usually). \$\endgroup\$

May 18, 2021 at 14:42

\$\begingroup\$ Any tool used improperly has the opportunity to destroy. Tools are not idiot-proof! \$\endgroup\$

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