Main purpose:Repair of electronic devices.
The device described below measures: ESR electrolytic capacitors Capacitance of electrolytic capacitors Capacitance of non- electrolytic capacitors Inductance
Frequency
Device supply voltage Current consumption
– 0 – 50 Ohm
– 0.1 – 60 000uF – 1pF – 2μF
– 0.1 μH – 1 H
– up to 50 MHz
– battery 7 – 9 V – 10 – 30 mA
Additional functions:
- In ESR mode, you can measure constant resistances 0.001 - 100 Ohm, resistance measurement circuits with inductance or capacitance are impossible (since the measurement is carried out in pulse mode and the measured resistance is shunted). To correctly measure such resistances, you must press and hold the “R" (first button). In this mode, the measurement is made at constant current10mA, the range of measured resistances is 0.001 – 20Ohm.
- In ESR mode, for in-circuit measurements, there is an analyzer (see below for a detailed description).
- In frequency meter mode, when the “L/C_P/F” button is pressed, the “pulse counter” function is activated (continuous counting of pulses arriving at the input “Fx "). The counter is reset "+" button.
- Low battery indication.
- Automatic shutdown - about 2-4 minutes. After the idle time has expired, the inscription “StBy” lights up and within 10 seconds, you can press any button and work will continue in the same mode.
Rules for using the meter.
Turning on - briefly pressing any of the buttons.
Switching modes in a circle – “ESR/C_R” – “Lx/Cx” – “Fx/Px” – with the “ESR/set” button.
ModeR_ESR/C.
In this mode, simultaneous measurements are madeESR and electrolytic capacitances (and not high-capacity electrolytic capacitors or fixed resistances0 – 100 Ohm. At press the “+” button, resistance measurement0.001 – 20Ohm, measurement is carried out at constant current10mA.
Analyzer data is displayed only when measuring capacities above60uF. and ESR below ~1.5ohm.
Connect the probe to the upper socket.
After some time, the probes oxidize and to restore reliable contact, it is enough to wipe the tip with fine sandpaper.
Zero setting.
This procedure is necessary every time when measuring using probes or an adapter, i.e. if the measurement is made using an adapter, set to zero with the adapter closed. If you then measure using probes, the resistance of the probes will be added to the measurement results. However, the difference in measurementThe ESR will not be large, but the analyzer readings will be overestimated by about0.25 ohm (this value for the analyzer is provided by a body probe 20 cm long) and for for the analyzer to operate correctly, it is necessary to set the zero with the probes closed,
Zero is set automatically, with the probes closed, by pressing the corresponding buttons. To do this, close the probes, press and hold the “L/C”0”-”(second button). On The display will show the ADC value without processing. If the display values differ by more than +/-1, press the button “ESR/set”, and the correct value “EE>xxx<” will be written. See photo:
When measuring, the lower value will be subtracted from the upper value and the result will be zero. For reliable contact, it is recommended to close the probes by injecting into the solder, see photo.
When the zero is correctly set, the readings on the display should be zero, or a small positive value.
For the constant resistance measurement mode, zero setting is also required. To do this, close the probes, press and hold the “+” and “-” buttons (the first and second button). If the display values differ by more than +/-1, press the “ESR/set” button, and the correct value “EE>xxx<” will be recorded. See photo:
This is what a measurement looks likeESR and electrolytic capacitor capacitances.
Good capacitor: Faulty capacitor:
In the left photo, a new capacitor,ESR 0.032 ohm capacity 963 μF. For a 1000uF capacitor, such parameters are considered excellent. This capacitor can be installed in any household appliance.
In the right photo, there is also a new capacitor, the capacity is normal,ESR is higher than normal. Such The capacitor can work in transformer power supplies and in audio equipment. It cannot be installed in switching power supplies or in power supply circuits of digital equipment.
The analyzer's readings, when measuring soldered capacitors, do not carry any information and do not differ much between different copies.
Below are approximate tolerance dataESR for switching power supplies. This data based on practical repair experience. With such values, in many cases, there was a deterioration in performance, but did not yet lead to complete inoperability.
As we see,ESR depends on capacitance. The larger the capacity, the lower the ESR. The table shows the data for low voltage capacitors6.3 - 63 volts. With increasing operating voltage ESR increases for higher voltages400 volts can be multiplied by 3.
At the initial stage, it is enough to remember a few of the most common values and then navigate according to them. The exact limits of serviceability of capacitors according toESR does not exist. All depends on the function that the capacitor performs in the circuit.
To understand the effect of increasingESR for circuit performance, can be simplified imagine a circuit with a resistor Fig.1. On resistor R1, with a load current of 2 amperes, a drop voltage0.4v. As a result, from the incoming 3 volts, the output is 2.6v. About the same happens in the scheme with a capacitor with increased ESR, Fig. 2. If the capacitor is charging pulse voltage, due to the voltage drop across the resistorESR (R1), the load will be give in to0.4 volts less. As a result, at the output we get a voltage with a ripple of 0.4v. At supply voltage3v, ripple 0.4v is more than 10%. If such voltage is supplied processor, the device will not work.
If the load current is reduced ten times to200mA, then the ripple will decrease tenfold, to 0.04 volt. In such circuits this capacitor will work.
If the supply voltage is increased to100 times up to 300 volts, then a ripple of 0.4 volts is about 0.01%. In such circuits, this capacitor will work and therefore for high-voltage circuits,ESR capacitors can be several times higher. In cases where an increaseESR is not great, the repairman himself must decide whether a given capacitor is the cause of the malfunction of the entire device.
This is what a resistance measurement looks like
There are charge pulses at the input - measuring the resistance of circuits with inductance or capacitance is not possible.
Resistance measurement range0.001 – 100Ohm,
When the “+” button is pressed, there are no charge pulses at the input, measurement is performed at constant current 10mA. In this mode, it is possible to measure the resistance of circuits that have inductance or capacity.
Resistance measurement range0.001 – 20Ohm,
In-circuit measurements.
The main difference between this meter and previous versions is its expanded capabilities for in- circuit measurementsESR.
Electrolytic capacitors are often shunted with an inductance of less than1 μH and ceramic capacitors up to50uF. With such shunting, in normal mode, the device is not able to detect faulty electrolytic capacitor without soldering. For these purposes, an in-circuit analyzer function has been added. The analyzer detects non-linear areas when charging the measured capacitor (a working capacitor is charged linearly). Next, the expected deviation is calculated mathematically and added to the value ESR(Rx)=aESR(a). On display, additionally the value “a0.00 ohm.” This function is most effective when measuring containers higher200uF. The analyzer value is displayed when measuring capacitances above 60 μF and ESR (resistance) below 1.5 ohms. In cases where there is no data for the analyzer, “a...” appears on the display.
In modern technology, more than half of the defects are associated with electrolytic capacitors. The serviceability of semiconductors and resistors can be calculated by measuring DC modes, as well as by “testing” the resistance. The serviceability of electrolytic capacitors cannot be determined by measuring modes or oscillograms when the device does not turn on. It is difficult to unsolder each capacitor and measure its parameters. In such a situation, the fastest way is in-circuit troubleshooting.
The vast majority of capacitors have defects:
increaseESR and loss of capacity or increase ESR capacity is normal, so in most cases, by sizeESR, it
is possible to perform in-circuit defectiveness of the capacitor.
During in-circuit measurements, various radio components installed in the circuits of the capacitor being measured introduce an error into the measurements, which makes it difficult to find the faulty one.
To use the meter more effectively in in-circuit measurements, it is necessary to remember its behavior when measuring in different blocks and with different shunting.
If the capacitor being measured is shunted by a transistor, diode (including Schottky) or any other semiconductor, the meter is able to correctly measure both capacitance andESR.
In real circuits, these are the primary circuits of switching power supplies (mains capacitor, power supply to the PWM controller, output of the optocoupler), as well as in most places of analog equipment.
Rice.1 Rice.2
When measuring marked capacitors, in the diagrams Fig.1, Fig.2, the meter will show correctly capacity
andESR. In such places, the defective capacitor is easily determined by the ESR value and containers.
If the capacitor being measured is shunted with a low-impedance resistance (resistor), correct capacitance measurement is not possible. The meter will show the inscriptionCx>-max- or will show capacity significantly higher than normal. With this connection, the faulty capacitor is determined by the value ESR.
In Fig.4-7, shows the shunting of a faulty capacitor 1000uF ESR-1ohm, various resistances. When shunting with a resistance lower100 ohm - capacitance readings increase on10%. Below 20 ohms, capacitance measurement is not possible. The inscription “Cx>-max-“ means that There is a capacitor in the circuit, but it is not possible to charge it to measure the capacitance. In such places, a defective capacitor is easily determined by its valueESR. As we see, from the given above examples, in all cases the meter will show an excessESR (for 1000 μF – the norm is up to 0.12 ohm).
If the capacitor being measured is shunted by inductance (below1 μH), ceramic high-capacity capacitors (more than10 μF), or if the shunting is complex, at the same time many elements of the circuit, its serviceability can only be determined using an analyzer.
The analyzer value is displayed in “ohm”. When measuring in-circuit, the health of capacitors is determined by the larger value,ESR or analyzer.
On rice8, faulty capacitor C2 (ESR-1ohm), shunted by resistor R2, inductor L1 and a working capacitorC1. With such a measurement, the readings will be ESR>0.050, the analyzer will be 0.30. We look at the larger value, i.e. the analyzer. Meaning0.30, according to the ESR table for 1000uF, corresponds to a faulty capacitor.
On rice9, faulty capacitor C2 (ESR-1ohm), shunted by unknown circuit elements. There is bypass surgery in which the indications areESR>0.300, more than the analyzer 0.20. Let's look by the larger value, i.e. byESR>0.300. The value 0.300, according to the ESR table for 1000uF, corresponds to faulty capacitor.
When measuring two parallel-connected electrolytic capacitors located close to each other, Fig.10., it will not be possible to determine the serviceability of each of them. Capacities of both capacitors will add up,ESR is less than the value of one of the capacitors, the analyzer is close value on both capacitors.
When measuring two electrolytic capacitors connected in parallel, connected by long printed tracks or wires, Fig.11., it is possible to determine if it is faulty only with using the analyzer. The capacitances of both capacitors will add up,ESR - close value on both capacitors, analyzer – increased value on a faulty capacitor.
In real circuits, electrolytic capacitors are primarily tested in areas with elevated temperatures. Near radiators and other heating elements.
It should be remembered that in-circuit measurements cannot give a 100% result, but in many cases they can save significant time.
The ability to measure small resistance values can be used when repairing complex circuit boards.
For example, in the event of a short circuit in the power supply, where dozens of elements are connected, many elements have to be soldered or traces have to be cut to reduce the search area, but by the lowest resistance you can immediately limit the search area; even the resistance of the printed tracks is measured here. Resistance of printed track width2mm, at a distance of 1.5cm from the closed area, amounts to0.003 – 0.004 Ohm. With such an in-circuit measurement, to eliminate the influence capacitances and inductances, in modeRSR, press and hold the “+” button, the measurement will be be carried out at constant current at the input.
------------------------------------------------------------------------------------------------------ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - From a set of elements connected in parallel, the element with a short circuit can be determined by the lowest resistance.
Faulty item: Functional item:
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Measurement of capacitance of non-electrolytic capacitors and inductance. Switching on non-electrolytic capacitors to the mode for measuring inductance and capacitance -
briefly pressing the second buttonL/C. Switching modes in a circle - with the “ buttonESR/set".
Measuring range:
Capacity – 1pF – 2μF Inductance – 0.1 μH – 1 H
If the accuracy decreases, it is possible to measure capacitance -0.1pF – 4μF, inductance from 0.01 μH.
Switching between capacitance and inductance measurement modes - button “L/C_P/F/”, located on the front panel. We connect the probe to the middle socket.
Setting zero - pressing ~2 sec “+“ buttons. In this case, in the capacitance measurement mode, the probes should be open, and in the inductance measurement mode the probes are closed.
Resonance type measurement method. This method has its advantages and disadvantages.
Advantages:
Resonance methods make it possible to measure the parameters of high-frequency inductors in the range of their operating frequencies. Accurately measured, small values of capacitance and inductance. Flaws:
1). As a result of the measurement, the self-capacitance of the inductors is not taken into account. At measuring large inductances (above ~2 miles Henry), having a large own capacity, readings will be underestimated.
2). It is not possible to measure inductance where there are several windings combined by
one core (transformers, etc.).
This is what measuring the capacitance of non-electrolytic capacitors looks like.
This is what an inductance measurement looks like.
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Frequency measurement,pulse counter.
Switching on the frequency measurement and pulse counter mode - briefly pressing the first buttonF/P
Switching modes in a circle - with the “ buttonESR/set".
Switching between frequency meter and pulse counter measurement modes - button “L/ C_P/F/” located on the front panel. We connect the probe to the lower socket.
The input circuits are adapted to measure frequency directly on the quartz resonator of a working device. This is necessary for testing quartz oscillators when repairing various electronic devices. The frequency is stably measured up to40 MHz.
When measuring a digital signal, to reduce interference, switch the input divider to position "14". Switching the input divider “1: 1” and “1: 4”.. – press for 1 second the second L/C button. This is what a frequency measurement looks like:
This is what the pulse counter looks like:
Pulse counter, counts the number of pulses received at the input. Reset with the first button.