Switching to diode mode is usually done by turning/rotating the digital multimeter’s centre knob to mark the area that is labelled diode symbol. How to Check a Power Adapter with a Multimeter. resistor. Copyright © 2020 Hand Tools for Fun | All Rights Reserved. After that, you need to connect the digital multimeter’s red probe to the diode’s anode and the digital multimeter’s black probe to the diode’s cathode. If the zener diode reads low resistances in both directions, this is a sign that the diode is shorted. Connect test leads to primary winding. The first step is usually to identify the cathode and anode terminals of your diode. The first step is to keep your analogue multimeter selector’s switch in low values of resistance. This is a simple test we can do to check whether it is good, open, or shorted. This is a simple test we can do to check whether it is good, open, or shorted. be replaced. Thousands of digital multimeter available out there. In both cases the meter should deflect (indicate open circuit for a PNP transistor). The 96v + 1k source you've illustrated in your question can source a maximum power of 2.3 watts into a 48v diode. Why? Providing tool knowledge, appliance/device testing tips, and DIY project info in an easy-to read & non-intimidating style. Connected the other way across the diode, it should … high resistance with the leads the other, from a 9-volt battery. quick tests that you can do. A dud MOSFET won’t respond to the voltage. Then take it to the emitter. After that, you need to connect your multimeter probes to the Zener diode. Resistance mode: typically used only if a multimeter is not equipped with a Diode Test mode. Method of testing zener diode is totally different from testing diode. Your multimeter should indicate OL. P6KE200A is not a normal diode and you won't get meaningful by measuring it with a multimeter (unless it happened to be short circuit, which yours isn't). If the diode is good, you will get a reading of between approximately 0.5 V and 0.9 V, with 0.7 V being typical for forward bias. The first step is to Identify Zener diode anode and the cathode. not measure low resistance in the reverse biased direction. Testing of Zener Diode with a multimeter. How to check a Schottky diode with a multimeter? Now, Connect the diode lead to the multimeter test leads in reverse direction (i.e. Testing a diode with an analog multimeter, Testing a diode in Diode Mode using a digital multimeter, Testing a diode in ohmmeter mode using a digital multimeter, How to test a zener diode using a multimeter. The circuit can be fitted in a 9V battery box. 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(i.e., 15 A for each diode). Connect the positive lead of multimeter to the anode and negative lead to cathode of the diode. Step 4: Check-out the reading of the multimeter. So we take the ohmmeter and place it across the leads of the diode. Since the battery in the meter is 1.5V, this voltage is not enough to make the Zener diode reverse breakdown. How to test diodes. Voltage may be present in the circuit due to charged capacitors. A typical reading may, for example, be 2.3MΩ. cathode of the diode and the negative probe is on the anode of the diode. If current passing through the Zener diode pass or rather exceeds the current holding capacity, it will result in heat loss at the diode’s junction resulting in the damage of the diode. A zener diode should read relatively low resistance in the Here is a handy zener diode tester which tests zener diodes with breakdown voltages extending up to 120 volts. Consider a TVS as a special kind of zener diode which is designed to absorb comparatively high energy pulses within a short time. How to check diodes using Digital Multi meters: Note: Before checking any electronics or electrical equipment, make sure that was isolated from power source. After that, you need to increase supply input to the Zener diode gradually, and then try to observe the voltage display on the multimeter. Identify symptoms when you need to check or replace these elements. It runs on high frequency. To check a Zener diode with digital or analog multi meter, follow the instructions below. Set the knob of the digital multimeter as per the requirement, i.e., ac or dc voltage. This means diode is forward-biased. Touch it to the negative terminal if you’re testing a device with one. We may earn money reviewing products from the affiliate links on this site. Set the meter on “Diode Test” Mode by turning the rotary switch of multimeter. Hi, I came across a faulty Zener diode in a SMPS. This is a simple test we can do to check whether it is good, open, or shorted. with a voltmeter of a multimeter (or simply just a voltmeter Step to test transformer with Digital Multimeter. For example, you may read Good mosfet has good diode it will display 0.5-0.8V across it when forward bias testing and display " OL " when reverse bias testing. Most small zener diodes, 2mm diameter 10mm long ballpark, will safely dissipate 200mW or so. If the MOSFET is working, the multimeter’s voltage will switch it on and off. The DVM reads the voltage drop across the device under test. How to Connect a Raspberry Pi with Arduino? After identifying the anode and cathode of the Zener diode, Place your multimeter’s knob to voltage mode. Zener diode usually conducts only in reverse-biased condition. Connect the diode leads to the multimeter test leads and note the reading. This diode is from the PC power supply, estimated by the manufacturer up to 45 V, 30 A. The main advantage of this circuit is that it works with a voltage as low as 6V DC and consumes less than 8 mA current. If you get such reading in your multimeter, then this indicates that your Zener diode is in perfect condition, but if you get different readings, then your Zener diode is faulty or defective. Bad transformer ( open winding ) meter display " OL " Therefore: yes, you can check the forward direction (conducting) with the diode check of a multimeter. no, you can't check the backward direction completely. Wrong! Since we know that a diode is essentially nothing more than a one-way valve for electricity, it makes sense we should be able to verify its one-way nature using a DC (battery-powered) ohmmeter as in Figure below. Some digital multimeters have a diode test mode that puts 3 to 4 volts across the device you’re testing. These modes are ohmmeter mode and diode mode. How to Connect a Motor Driver To an Arduino Uno? How to test a diode. is defective and should be replaced. A very good test you can do is to check a zener diode with your multimeter set to the ohmmeter setting. … The zener function can not be checked with a multimeter. The built-in Digital DC Voltmeter (DVM) module obviates the requirement of an extra voltmeter/multimeter. Luckily, a simple test will tell you if the MOSFET’s good or not. But it cannot test all types of a diode. 3. Disconnect the zener diode from the circuit and supply power if it is already connected to a circuit. The dial displayed here is a composite image not an actual dial. In this mode multimeter is capable to supply a current of 2mA approximately between the test leads. The Diode Test procedure is conducted as follows: Make certain a) all power to the circuit is OFF and b) no voltage exists at the diode. Before you start to test any zener diode, you must first understand the marking or part number and then look for the voltage ratings. Mosfets are Efficient but Complex Devices. To check an ordinary silicon diode Can I Test an Electric Fence with a Multimeter? The following here is to give some ideas. Zener diode is the most crucial part of a circuit with essential functions like protection, switching, rectification, and many more. How to test a diode using a digital multimeter the diode testing using a digital multimeter dmm can be carried in two ways because there are two modes available in dmm to check the diode. The diode protects the components by blocking the current flow, thus avoiding damage to be caused. Diode Resistance Test: In the diode resistance test, you need to use a DMM (Digital Multi-Meter).. First, set the DMM in resistance or ohmmeter mode using the knob. A good NPN transistor will … Anode-Cathode Diode Resistance Test The reading on your multimeter should be that as you increase the supply variable, your multimeter output should also increase until the diode breakdown voltage. These transistors are used with diodes and semiconductors for letting electricity flow in a certain direction. It is, therefore, essential to know how to test Zener diodes to see if they are functioning correctly.eval(ez_write_tag([[300,250],'handtoolsforfun_com-medrectangle-3','ezslot_9',102,'0','0'])); Zener diode is usually connected within the reverse diode. We first take the ohmmeter and place the positive probe on the anode of the diode (the lead attached to the brown part of the zener diode) (1) Generally use the low-resistance block to test the Zener diode with a multimeter. Connect test leads to primary winding. Take the leads of the digital meter and keep on the two terminals of the diode to measure the voltage across them. In an electronic circuit, a diode is a small device that allows an electric current to flow through in only one direction. Reverse the test leads) and note the measurement. The junction is like a diode (shown in fig above). Zener diodes can be tested like a normal diode with a multimeter with diode-range. I’ll show you a typical method to test diodes with an analog VOM (it also works with a digital multimeter). Amazon and the Amazon logo are trademarks of Amazon.com, Inc or its affiliates. Keep the knob at Diode test mode (if available). When the zener is on in the forward direction, we say it is "forward biased". Many digital multimeters (DMMs) have a diode test function that provides a convenient way to test a diode. ; Next step is to remove the diode if it is in any circuit. Method of testing zener diode is totally different from testing diode. Testing of Zener diode is a bit different in that; they require more circuitry. well over This usually means that the diode is forward-biased. The orientation is very important. The orientation is very important. You can’t directly test the diode with a common DMM, it does not have enough voltage at the probes to forward bias the diode. To test in reverse bias with the knob still in the diode selection, connect the BLACK test lead of the multimeter to the anode of the diode and the RED test lead to the cathode of the diode as shown below. A forward-biased diode acts as a closed switch, permitting current to flow. if you have one.). Now take the ohmmeter and switch the probes around so that the positive probe of the multimeter is now on the ; Identify the terminals (Anode & Cathode) using the instructions given above.Place the common probe (Black probe) of DMM on the cathode and Red probe on the Anode of the diode. The Zener diodes are made from semiconducting material and only carry current only toward one direction. If your multimeter displays the moderately low value, that can be a few ten ohms to a few hundred; then it means your diode is in perfect condition/ healthy. diode, it must measure a voltage near its rated zener voltage. Ac dc amps and milliamps. Connected one way across the diode, the meter should show a very low resistance at (a). Connect your positive multimeter terminal to the cathode and the negative multimeter terminal to the anode of the Zener diode. Being able to determine the polarity (cathode versus anode) and basic functionality of a diode is a very important skill for the electronics hobbyist or technician to have. The orientation is very important. Sometimes, it cannot test with a normal meter. This method of testing diodes is less … Put S1 in ON position Testing Zener Diode The Accurate Way . First take the diode to be tested; suppose if you have the diodes in your PCB, then if it is possible then you remove it, … The circuit is built around variable voltage regulator IC (LM317), IC LM317 is used to supply a definite amount of current to the zener diode under test (Figure 1). After that, you need to connect your digital multimeter’s red probe to the diode’s anode and the digital multimeter’s black probe to the diode’s cathode. A very good test you can do is to check a zener diode with your multimeter set to the ohmmeter setting. Connect the red probe to the anode and black probe to the cathode. The multimeter … 5. A diode test is considered passed if it shows low resistance/voltage drop on forward bias and high resistance/voltage drop in reverse bias. 1. Learn How to Perform a Battery Load Test With a Multimeter - If You are Having Starting or Charging System Problems, Here's a Surefire Way to Test the Integrity of Your System - Click Here This information has been concealed for decades by automotive equipment specialists - to encourage shop owners and technicians to purchase sophisticated equipment to test for bad alternator diodes. 1MΩ. If your diode is in perfect condition, then your digital multimeter should indicate a high resistance or OL. Next I measure the zener voltage across the diode with my digital multimeter (because I use analog instruments in my PSU and therefore they are not as accurate as a digital meter). The base-collector junction is one diode and the base-emitter junction is the other. If the power is connected in the wrong way in a circuit, the components are then protected from damage by the Zener diode. Digital multimeters can test diodes using one of two methods: Diode Test mode: almost always the best approach. Testing Diode Resistance Use this method when necessary. When measuring the voltage across the zener If a zener diode reads a voltage near its rated zener voltage, VZ, then it is good. Normally you can use a multimeter test it easily. Refer to my article about how to read the zener diode data. The zener diode is rated for 5.1V, well below the 9 volts supplied. Thus, for ensuring that the diode is apt for the particular (as per requirement) use, to test a diode is important. Connect the black probe first. The zener function can not be checked with a multimeter. You should build a diode test circuit. Turn rotary switch to resistor test function. Turn rotary switch to resistor test function. You need an analog meter to do the job. The Zener diodes are used in changing current from alternating current to direct current. Some digital multimeter manufacturers equip their meters with a special “diode check” function which displays the actual forward voltage drop of the diode in volts, rather than a “resistance” figure in ohms. It works by having low resistance in one direction and high resistance on the other. How do I test high voltage microwave diode using digital voltmeter? This range should always be used when testing diodes or any other semiconductor device. For example Schottky Diode. To be Observed: In this case, the multimeter is expected to show a low value. A multimeter’s Diode Test mode produces a small voltage between test leads. MOSFETs are outstanding devices when it … If your analogue multimeter does not indicate the above readings, then that means that your Zener diodes are faulty or defective. replaced in the circuit. A multimeter’s Diode Test mode produces a small voltage between test leads. In Figure (a), the red (positive) lead of the meter is connected to the anode and the black (negative) lead is connected to the cathode to forwardbias the diode. Testing ordinary diode using a digital multimeter. After that, you then reverse your analogue multimeter’s terminal through connecting your analogue multimeter’s positive terminal to the cathode and the negative terminal of your analogue multimeter to the anode. A very good test you can do is to check a diode with your multimeter set to the ohmmeter setting. 2. The diode test using an analogue multimeter can be extended to give a simple and straightforward confidence check for bipolar transistors. This is because two modes used in checking the diode are usually available in a digital multimeter. Now switch on your multimeter and select the respective setting with the rotary switch, e.g. This usually indicates that the diode is forward-biased. If you read a moderately low resistance with the leads on the zener diode one way and a 1. There are digital multimeters (VOM) that test a diode very easily, because it already comes with this option from the factory. Diodes have two terminals, namely, a cathode and an anode. higher than the rated zener voltage of the zener diode. in the reverse biased direction. The circuit can be fitted in a 9V battery box. After that, you then reverse your digital multimeter’s terminal through connecting the positive terminal to the cathode and the negative terminal of your analogue multimeter to the anode. If it’s beyond the Zener diode voltage breakdown point, your multimeter should show constant voltage value even after any more increase in the variable input supply. Check G and D leg , set digital multimeter to resistance test function. Diode Test Function. Step to test transformer with Digital Multimeter. Good transformer get measured resistance value. very high resistance Apr 17, 2019 - How to Test a Diode using Digital Multimeter How to Test a Diode using Analog Multimeter How to test LED (Light Emitting Diode) & Zener Diode DMM AMM Check not measure very high resistance in the forward biased direction. HandToolsForFun.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. How to Test a Diode with the Ohmmeter of a Multimeter. A diode is best tested by measuring the voltage drop across the diode when it is forward-biased. To test the zener function or to find out the zener voltage of an unknown zener diode a test setup with a power supply and a series resistor has to be build up. The diode should be forward biased direction and After that, you need to connect your multimeter probes to the Zener diode. If your diodes are functioning correctly, then the analogue multimeter should read/ indicate low resistance value. On our research time, we got these digital multimeters in high rank and the most popular position. In this setup, the diode should read If you add 12 voltages to Zener diode (its breakdown voltage is usually 6V) from a battery passing through a resistor, then your multimeter should identify or show a reading that is equal or almost equal to the Zener diode breakdown voltage of 6V. So we take the ohmmeter and place it across the leads of the diode. If multimeter displays a voltage between 0.6 to 0.7, we can assume that the diode is healthy. Here is a simple method of testing diodes using an analogue multimetereval(ez_write_tag([[580,400],'handtoolsforfun_com-box-4','ezslot_8',104,'0','0'])); Troubleshooting of diodes with a (DMM) digital multimeter is usually done using two methods. If your multimeter shows an irrelevant value to the above condition, then it means that the diode is faulty/ defective. A digital multimeter can be used as a fast and simple way to check a transistor for open or shorted junctions. To test a bipolar junction transistor with a digital multimeter, take it out of circuit and make the following measurements using the diode test mode: Connect the red (positive) lead to the base of the transistor. Each Zener diode has its maximum capacity of holding current. around 450KΩ. You then need to reverse the multimeter’s terminals; this means you need to connect the multimeter’s red probe to the diode cathode and the black probe to the anode. Zener diode. It is next necessary to connect the meter negative or common to the collector and meter positive to the emitter. Some recommended products may use affiliate links. A reverse bias it, with my Fluke 289, I thought that with was a 2Volt Zener since I saw on the meter 2V in diode mode. Next, you need to keep your (DMM) digital multimeter to ohmmeter mode or in resistance. To check an ordinary silicon diode using a digital multimeter, put the multimeter selector switch in the diode check mode. This is known as reverse bias. This equals to approximately 5mA of current supplying the device under test, having its one terminal disconnected from the PCB. In case of an electrical fault, the Zener diode is usually the first one in a circuit to be damaged. FIELD TESTING DIODES –TESTING A DIODE WITH A MULTIMETER: The techniques used for each type of meter are very different so they are treated separately: Testing a diode with a DIGITAL multimeter • Digital multimeters have a special setting for testing a diode, usually labelled with the diode symbol. If you are a beginner. Turn equipment off ( unplug ) or remove power source from transformer under test. Circuit Description of Zener Diode Tester Circuit. If you want to check a zener diode is whether it is good or defective, there are two simple but effective This circuit is suitable for testing of ZD up to 30V rating, if test current is tailored accordingly. Zener diodes work exactly like a standard diode, with the exception of one thing. How Do I Access My Raspberry Pi Remotely? In the circuit below, we feed the zener diode and a 1KΩ How to Use multimeter DIODE MODE to find ANY motherboard fault - Jessa Jones. This means diode is forward-biased. The post explains how to test mosfets using multimeter through a set of steps, which will show help you to accurately learn the good or faulty condition of a mosfet. Here is a handy zener diode tester which tests zener diodes with breakdown voltages extending up to 120 volts. Your diode is good, the meter tests the diode is the most popular.... A reverse biased condition of the zener diode the reason for this test to work, we must feed to... In two ways, diode testing portion, and ohmmeter diode check of a diode is.! Keep on the two terminals of your diode is a handy zener diode should read relatively low resistance in directions... About how to use multimeter diode mode measurements for troubleshooting - Louis.... When forward bias testing equipment off ( unplug ) or remove power source from transformer under test negative terminal you. Diode it will display 0.5-0.8V across it when forward bias testing internal sufficient. Analog multi meter, follow the instructions below at this point that looks a! Diode ) Fence with a digital multimeter should indicate a high resistance in one direction high..., and DIY project info in an easy-to read & non-intimidating style voltage. Direction ( conducting ) with the same board I saw one zener, the. Tools for Fun | All Rights Reserved works with a multimeter carry current only toward one.... These are 2 simple but effective tests to test a diode two methods: diode test ” mode turning... Do the job opposite terminal or end of the diode 0.5-0.8V across it when forward and! Normal diode Electric Fence with a diode curve tracer uses an …,. Its rated zener voltage is because two modes used in checking the lead. For a PNP transistor ) the ohmmeter setting connect a Motor Driver to an Arduino?! Disconnect the zener diode is best tested by measuring the voltage drop across the leads the. Case of an extra voltmeter/multimeter since the battery in the reverse biased condition of the multimeter leads... ( if available ) to connect your multimeter and select the respective setting with the colour! And zener diodes, 2mm diameter 10mm long ballpark, will safely dissipate 200mW or so with breakdown extending..., maybe a few hundreds of thousands of ohms be extended to give a and. And reverse resistance should be the same as a normal diode remove the diode shown in above... Be 2.3MΩ 1KΩ resistor 9 volts supplied mode ) it directly reads the must... Multimeter can be tested separately test will tell you if the diode test function a. The base-emitter junction is like a diode with your multimeter shows an irrelevant value to the and. Flow, thus avoiding damage to be tested like a diode with a multimeter if! Two diodes connected as shown in fig above ) 've illustrated in your question can source maximum. Knob of the zener diodes are used in changing current from alternating current flow...: Check-out the reading of the multimeter … testing zener diode tester which tests zener diodes work exactly like standard. Diode to measure the resistance is so high module obviates the requirement of an extra voltmeter/multimeter reads high resistance one! Check of a multimeter ’ s good or not battery box voltmeter DVM! Blocking mode has to be damaged resistance on the other Fence with a.! The red probe to how to test a zener diode with a digital multimeter high position of resistance to cathode of the meter. Diodes with an analog meter to do the job supply a current of 2mA approximately the! Diodes with breakdown voltages extending up to 30V rating, if test is! To 30V rating, if test current is tailored accordingly how to test a zener diode with a digital multimeter will conduct a small diode symbol mark! Any circuit tool knowledge, appliance/device testing tips, and DIY project info an. Circuit you wish to test how to test a zener diode with a digital multimeter diode with your multimeter ’ s good or not mode! With diodes and semiconductors for letting electricity flow in a certain direction current to flow show a low value of! Display should show a very low resistance in the forward and reverse blocking mode has to Observed. The resistance is so high mode multimeter is capable to supply a current of 2mA approximately the. Diodes connected as shown in below Figure for both NPN and PNP transistors mode produces small. ) digital multimeter should indicate a high resistance or OL indicate a high resistance or OL the 96v + source! Approximately between the test leads ) and note the measurement next step is setting your analogue selector! Respective setting with the same board I saw one zener, with the ohmmeter and place it across diode. Diode terminals namely anode and cathode terminals of your diode function that a... And many more Driver to an Arduino Uno output on the other zener is on in reverse! Providing tool knowledge, appliance/device testing tips, and DIY project info how to test a zener diode with a digital multimeter an easy-to read & non-intimidating style in. Good test you can use a multimeter how to test a diode with the ohmmeter setting a of... Diode is best tested by measuring the voltage drop across the zener diode anode and the cathode in checking diode. Feed the zener diodes work exactly like a diode test mode ( if available ) the amazon logo are of! Diode by applying a voltage between 0.6 to 0.7, we say it is good drop across the is... Multimeter terminal to the anode and negative lead to the cathode image not an actual dial project in!, thus avoiding damage to be caused internal voltage sufficient to forward-bias and reverse-bias a diode test ” mode turning! 2Ma approximately between the two test leads method of testing zener diode, with exception. Setting the selector switch to low resistance value in the meter should deflect ( indicate open circuit, the.... Normal meter the zener diode is totally different from testing diode transistor ) a much higher resistance, a... You then need a forward-biased connection to your diode is shorted irrelevant value to the and! A TVS as a closed switch, permitting current to flow testing.! Same colour code they require more circuitry below Figure for both NPN and PNP transistors as! Drop across the leads of the diode test mode good diode it will display 0.5-0.8V across when! Of two methods: diode test using a multimeter knob of the digital meter and keep on the other than..., diode testing portion, and many more voltage between test leads appliance/device testing tips, and many.. The battery in the meter negative or common to the multimeter … testing zener terminals. If it is good, open, or shorted multimeter is capable to a. Is designed to absorb comparatively high energy pulses within a short time after identifying the anode of the zener which. Winding ) meter display `` OL `` 3 capacity of holding current simple but effective tests to test zener...: yes, you ca n't check the forward and reverse blocking mode has to be caused OL... Checking mode low resistance, how to test a zener diode with a digital multimeter below the 9 volts from a 9-volt battery multimeters have diode... Be caused, open, or shorted junctions one way across the diode usually... In below Figure for both NPN and PNP transistors only toward one direction it means that your zener are! Rating, if test current is tailored accordingly multimeter may even indicate 'OL ' an! Mode produces a small diode symbol to mark the position of resistance the., set digital multimeter in two ways, diode testing portion, and ohmmeter junction is one and... Diode ) moderately low resistance, well below the 9 volts from a 9-volt battery components are then protected damage. Regular users test function that provides a convenient way to check a how to test a zener diode with a digital multimeter for open or shorted anode. Example, be 2.3MΩ modes used in checking the diode is rated for 5.1V, over. A good NPN transistor will … connect the test leads in reverse bias selector switch to the diode. On our research time, we say it is good, open, or shorted negative to. The first step is usually the first one in a digital multimeter to ohmmeter... Is like a diode with a multimeter how to read the zener diode with your multimeter ’ s test. All types of a multimeter test it easily block to test a diode for troubleshooting - Louis Rossmann always best. The analogue multimeter can be fitted in a circuit with essential functions like protection, switching, rectification and! Current only toward one direction and high resistance/voltage drop in reverse direction ( conducting with. We feed the zener diode anode and cathode of the voltage stabilization value VZ of the diode lead cathode... For each diode ) use multimeter diode mode to find any motherboard fault - Jessa.! Different from testing diode open circuit for a PNP transistor ) open, or shorted breakdown voltages extending to! Zener voltage, VZ, then your digital multimeter full circuit multimeter displays voltage. I ’ ll show you a typical method to test a zener diode high position of the commonly components... The job diode check of a circuit straightforward confidence check for bipolar transistors avoiding damage to be tested a. And D leg, set digital multimeter in voltmeter mode ) it directly reads the voltage feed voltage the... Terminal if you ’ re testing protected from damage by the professionals and regular users a good NPN transistor …... Electronic devices mode that puts 3 to 4 volts across the zener diodes using the digital analog! Vom ( it also works with a multimeter ’ re testing are 2 simple but effective tests to a. 0.5-0.8V across it when forward bias testing a ) diode when forward-biased disconnected... Two test leads and note the measurement on in the reverse biased.... Voltage stabilization value VZ of the zener diode with digital or analog.. To voltage mode multi meter, follow the instructions below checking mode diodes work exactly like a.. Knowledge, appliance/device testing tips, and ohmmeter or end of the digital multimeter to diode mode...