Browse technical resources about solar mounting systems, tracker technology, structural design, and installation best practices.
HOME / How To Remove A Capacitor Soldered To A Circuit Board - BeTheFuture Solar Foundation & Infrastructure
How to Desolder and Remove Capacitors From a Printed Circuit Board1. Heat Up Your Soldering Iron Plug in your soldering iron and set the temperature to around 350°C. Do the Same for the Second Leg.
Position the new capacitor leads at the holes where the old capacitor was, with the correct polarity. Just like before, press the tip of the soldering iron directly onto the joint in the back of the circuit board. As soon as the tip falls into the hole, press the wire lead through the hole, then remove the iron.
It'd be likely to grip the pcb capacitor. Warm your heat gun and push it to the capacitor's soldering back. Maintain the soldering iron in place until the capacitor separates from the circuit board. Then reverse the procedure to loosen the wire and remove the circuit board capacitor on the opposite side.
Mounting a new pcb capacitor is as important as learning to remove old and damaged capacitors. In this way, you will be able to complete the process of replacing the capacitor on the circuit board whenever you want and maintain the efficiency of the electric board properly.
Capacitors are essential components found on most circuit boards. They regulate voltage, smooth out power fluctuations, and store electrical charge. In this guide, we'll cover everything from different capacitors to how to replace them, troubleshoot problems, and find faults.
A capacitor is a basic component of a circuit board. It is responsible for storing electrical energy to help the device work properly. The capacitor may get damaged or blown away due to excessive or overheat and over-electricity. At this point, you must replace the capacitor to help the circuit board work properly.
When you witness one or more signals of a damaged capacitor that we mentioned above, you need to prepare to replace the unit. Thus, you will need the following accessories: A tool to open the device casing. Preferably, you should use a HEX wrench or screwdriver. The new capacitor ( you have to match its value with the existing capacitor)
The primary consideration for capacitor selection should be the nominal capacitance value. Knowing the application is important for determining the capacitance value. Either the designer calculates the capacitance or, in an integrated circuit application, the capacitance is recommended in the IC datasheet. Depending on. The tolerance of the capacitor is worth considering, as it gives information about the actual variation of capacitance allowed. A higher tolerance capacitor is not suitable for precision applications, and in such cases, the lowest. If the circuit or application you are dealing with is temperature-sensitive, then it is important to consider the capacitor variation versus temperature. The capacitance variation is. The voltage rating is the maximum continuous DC or AC voltagethat a capacitor can withstand without failing. Exceeding the voltage. The operating temperature is an important environmental factor in the selection of a capacitor. You can find the temperature rating of a capacitor by looking at its datasheet, and can make an appropriate selection by choosing a.
[PDF Version]When it comes to circuit boards, capacitors are widely used for various purposes, such as filtering, smoothing, and decoupling. In this comprehensive guide, we will delve into the world of capacitors on circuit boards, exploring their types, functions, and applications. What is a Circuit Capacitor?
When selecting capacitors for a circuit board, several factors need to be considered: Capacitance: Choose the appropriate capacitance value based on the specific application requirements. Voltage rating: Ensure the capacitor can withstand the maximum voltage present in the circuit.
Depending on the application, the size of the capacitor varies, either in its capacitance or physical volume. When considering the capacitor size for a given application, parameters such as voltage, current ripple, temperature, and leakage current must be considered.
Take into account the capacitance, voltage rating, ripple current rating, and temperature when selecting a capacitor. The physical size of a capacitor depends on the capacitance value. As the capacitance increases, the size becomes larger. The capacitance variation is temperature-dependent.
When sizing a capacitor, always choose one with a voltage rating higher than the maximum voltage in your circuit to prevent breakdown and damage. The capacitance value, measured in farads (F), indicates the amount of charge a capacitor can store for a given voltage.
Below are the most common types you'll encounter on circuit boards: Ceramic Capacitors: Widely used for decoupling and noise filtering. Electrolytic Capacitors: Known for higher capacitance values, commonly used in power supplies. Tantalum Capacitors: Compact and stable, often used in consumer electronics.
At its most simple, a capacitor can be little more than a pair of metal plates separated by air. As this constitutes an open circuit, DC current will not flow through a capacitor.
A capacitor is not well-described as an open circuit even in DC situations. I'd rather describe it as a charge-controlled ideal voltage source in that it can deliver and accept arbitrarily high currents at the cost of adapting its voltage depending on the delivered charge.
Capacitor: at t=0 is like a closed circuit (short circuit) at 't=infinite' is like open circuit (no current through the capacitor) Long Answer: A capacitors charge is given by Vt = V(1 −e(−t/RC)) V t = V (1 − e (− t / R C)) where V is the applied voltage to the circuit, R is the series resistance and C is the parallel capacitance.
Short Answer: Inductor: at t=0 is like an open circuit at 't=infinite' is like an closed circuit (act as a conductor) Capacitor: at t=0 is like a closed circuit (short circuit) at 't=infinite' is like open circuit (no current through the capacitor) Long Answer:
Then this is a closed circuit that will charge the capacitors. (sorry for the ascii circuit, the -| |- are capacitors, the MMM is a resistor, and the (-+) is a voltage source). Your argument is: If the circuit is open, the current must be zero. Consequently the field must be zero.
The circuit is open since the switch is open. My book says that the capacitor will only be charged when the switch is closed, but I don't see why this is true. I would expect the capacitor to be charged a little - not as much as if the circuit is closed, but still charged none the less.
Seeing it really helps you grasp what's going on. A capacitor looks like an open circuit to a steady voltage but like a closed (or short) circuit to a change in voltage. And inductor looks like a closed circuit to a steady current, but like an open circuit to a change in current.
Capacitors in series are capacitors that are placed back-to-back with the negative electrode of one capacitor connecting to the positive electrode of the other. Below is a circuit where 3 capacitors are placed in series. You can see the capacitors are in series because they are back-to-back against each other, and each. The formula to calculate the total series capacitance is: So to calculate the total capacitance of the circuit above, the total capacitance, CTwould be: So using the above formula, the total. Capacitors in parallel are capacitors that are connected with the two electrodes in a common plane, meaning that the positive electrodes of the. We'll now do a capacitor circuit in which capacitors are both in series and in parallel in the same circuit. Below is a circuit which has capacitors in both series and parallel: So how do. The formula to calculate the total parallel capacitance is: So to calculate the total capacitance of the circuit above, the total capacitance, CTwould be:.
[PDF Version]In a circuit, a Capacitor can be connected in series or in parallel fashion. If a set of capacitors were connected in a circuit, the type of capacitor connection deals with the voltage and current values in that network. Let us observe what happens, when few Capacitors are connected in Series.
Circuit Connections in Capacitors - In a circuit, a Capacitor can be connected in series or in parallel fashion. If a set of capacitors were connected in a circuit, the type of capacitor connection deals with the voltage and current values in that network.
In fact, since capacitors simply add in parallel, in many circuits, capacitors are placed in parallel to increase the capacitance. For example, if a circuit designer wants 0.44µF in a certain part of the circuit, he may not have a 0.44µF capacitor or one may not exist.
Connect the Capacitor: Determine the correct polarity of the capacitor terminals based on its markings or labels. Connect the positive (+) terminal of the capacitor to the positive (+) terminal of the circuit or device and the negative (-) terminal to the negative (-) terminal. Use soldering techniques if soldering is required for the connection.
In the below circuit diagram, there are three capacitors connected in parallel. As these capacitors are connected in parallel the equivalent or total capacitance will be equal to the sum of the individual capacitance. When a capacitor is connected to DC supply, then the capacitor starts charging slowly.
This proves that capacitance is lower when capacitors are connected in series. Now place the capacitors in parallel. Take the multimeter probes and place one end on the positive side and one end on the negative. You should now read 2µF, or double the value, because capacitors in parallel add together.
What you'll learn in this video: • The tools you'll need to replace your power bank battery • Step-by-step instructions on how to safely open and replace the battery • Important safety tips to k.
When battery disposal is not handled correctly, the battery can leak, potentially contaminating the soil and water, and possibly harming human health. Therefore, REWA will share a way to convert old phone batteries into a power bank, turning trash into treasure. Terminology: Anode = Positive terminal, Cathode = Negative terminal
The troubleshooting procedure for a power bank is based around checking two issues. Faulty Battery: If the battery has gone through severe over/undercharge, then the battery will be unable to hold a charge for longer periods of time. In such a case permanent battery damage is likely to occur & battery replacement is advised.
Following are the steps on How To Repair A Power bank at home. 1) Remove the upper casing of the power bank with respect to the manufacturer guide. Use a screwdriver to provide extra leverage if necessary. 2) Remove chasis 3) Begin by checking the battery: desolder the +ve & -ve terminal of the battery from the charger board circuit.
Solder the cathode of the battery to the cathode of the power board. Press the button. For this project, the power bank is 33% full. Apply foam to secure the battery. Install the middle frame to the housing and put on the bottom plastic cover. Connect the phone to the power bank. The phone can be charged. Connect the charger to the power bank.
Solder the anode of the battery to the anode of the power board. Solder the cathode of the battery to the cathode of the power board. Press the button. For this project, the power bank is 33% full. Apply foam to secure the battery. Install the middle frame to the housing and put on the bottom plastic cover. Connect the phone to the power bank.
You can also replace new batteries for full capacity of power bank. Small Introduction: Portable Power Banks are comprised of a special battery in a special case with a special circuit to control power flow.
Use our “Get an Estimate” tool to review potential costs if you get service directly from Apple. If you go to another service provider, they can set their own fees, so ask them for an estimate.
You have to buy the entire top lid that comes with that and other parts preattached, and it'll cost you more than twice the $199 that Apple charges for a battery replacement. Apple spokesperson Patrick Leahy confirmed to The Verge that a battery replacement part will eventually be available, but wouldn't say when.
Replacing your MacBook Air's battery with an iFixit Fix Kit can save you $30 to $90 compared to Apple's out-of-warranty repair costs, depending on your model. iFixit's MacBook Air battery replacement kits average around $100, while kits for newer models like the 2020 M1 cost around $130. ^ Apple's shared estimates as of February 2025.
If your Apple warranty has expired, and you wish to have the iPad battery replaced, you can register a repair request via the Apple website, the difference being that you will have to pay for the replacement battery, as well as shipping and handling charges, which should set you back by approximately $106 to $110, tops.
It expects you to lay out as much as $4,222 for a new logic board — ouch at having that on my credit card — but you'll get the vast majority of it back upon return. You should wind up paying $588 for a 16-inch MacBook Pro board, $500 for a 14-inch or 13-inch MBP board, or $368 for an M1 Air board, no matter how loaded it is.
Look for a reading that's higher than 10 volts. If the capacitor reads in the hundreds of volts, the safest way to discharge it is with a discharge tool, rather than a screwdriver.
Discharge Tool: For high-voltage capacitors, it's advisable to use a dedicated capacitor discharge tool, which often includes a resistor to safely dissipate the charge. – Insulated Tools: For lower-voltage capacitors, you can use insulated screwdrivers or pliers. 3. Discharge Process
The fastest way to discharge a capacitor is to place a metal object like a screwdriver across the terminals to shorten it. As you get a spark, it is best to do this for only low-voltage capacitors. Is it OK to discharge a capacitor? It is okay to discharge capacitors yourself using resistors or discharge pens.
Controlled Discharge: Take a systematic approach to discharge by using resistors to create a controlled discharge path. This prevents rapid capacitive discharges that can produce sparks or damage the capacitor discharging. Emergency Response Plan: Have a well-defined emergency response plan in place.
It is okay to discharge capacitors yourself using resistors or discharge pens. However, there are shock hazards, and you must be extra careful, especially when dealing with high-rated capacitors. Discharging a capacitor is a necessary process that should be done with caution. This guide will teach you the proper way to make capacitors empty.
Hold the probes and read the numbers in the multimeter display. Note: If the capacitor's stored voltage is below 10V, there's no need to discharge it, as it would be discharged by itself. Or you can connect both leads of the capacitor together, as it is shown in the picture below: Remember, it can be done for low voltage capacitors.
To safely discharge the capacitor without damaging the motherboard, desolder it from its position. Be careful not to short the two terminals (bridging the anode and cathode terminals) of the capacitor with your soldering iron, and also make sure you don't touch these terminals with your bare hands.
In a circuit, when you connect capacitors in series as shown in the above image, the total capacitance is decreased. The current through capacitors in series is equal (i.e. iT = i1 = i2 = i3= in). Hence, the charge stored by the capacitors is also the same (i.e. QT = Q1 = Q2 = Q3), because charge stored by a plate of any capacitor. When you connect capacitors in parallel, then the total capacitance will be equal to the sum of all the capacitors capacitance. Because the top plate of. When a capacitor is connected to DC supply, then the capacitor starts charging slowly. And, when the charging current voltage of a capacitor is.
Circuit Connections in Capacitors - In a circuit, a Capacitor can be connected in series or in parallel fashion. If a set of capacitors were connected in a circuit, the type of capacitor connection deals with the voltage and current values in that network.
In a circuit, a Capacitor can be connected in series or in parallel fashion. If a set of capacitors were connected in a circuit, the type of capacitor connection deals with the voltage and current values in that network. Let us observe what happens, when few Capacitors are connected in Series.
In a capacitor circuit diagram, a capacitor is represented by a symbol that looks like two curved lines in a circle. There are several different types of capacitors, and each one has its own unique characteristics. Electrolytic capacitors have the highest capacitance and are typically used for high-voltage applications.
To create your own capacitor circuit diagram, you need to first understand how capacitive circuits work. You'll also need some basic software or a circuit simulator program. Once you've created your diagram, it's a good idea to test it out on a breadboard first to make sure everything works as planned.
Hence, when two capacitors are connected in series, their equivalent capacitance can be directly calculated by multiplying the two capacitances and then dividing by their sum. Let's consider another special case, when two capacitors have the same capacitance, i.e., C 1 = C 2 = C. In this case, we get,
If a set of capacitors were connected in a circuit, the type of capacitor connection deals with the voltage and current values in that network. Let us observe what happens, when few Capacitors are connected in Series. Let us consider three capacitors with different values, as shown in the figure below.
Finding the location of your battery is the first step. Whilst most batteries can be found by opening the bonnet and looking in the engine bay, many modern vehicles have the battery located in the boot under the boot liner. Some vehicles may even have the battery located under the rear seat. If you're unsure of your. To ensure your safety, make sure you've turned off your ignition and remove the key (if you have one that connects into the ignition lock). Make sure the key remains removed when you reconnect the battery. Wear safety goggles and. Use the spanner, socket wrench or adjustable wrench to loosen the negative terminal. This should only take a couple of left turns. Once loosened. The positive terminal is marked with a '+' symbol and often has a black cap. The negative terminal is marked with a '-' symbol and often has a red cap. These caps will need to be. The next step is to find the spanner, socket wrench or adjustable wrench you need to remove the nut on the negative and positive terminals. In some cases, you will be able to get away with an adjustable wrench. Remember,.
[PDF Version]
As a rule of thumb, if you motor for five hours or more a day at medium speed, you should – depending on the technical equipment of the yacht – have charged your batteries sufficiently (with about 250 amps, depending on the engine/alternator and batteries) to be able to use normal consumers on board for a while. In. This could look like this: when the yacht is disconnected from shore power, after about ten to 15 minutes the voltage/volt of the consumer battery should be read and noted. Depending on the battery type, this voltage/volt may be. By the way, the lion's share of electricity consumption on the yacht is usually the refrigerator. The consumes on average about 100 watts (eight. Here are a few rough guide values for orientation: 1. Refrigerator per day about 120 amps 2. Pressurized water pump per person per 24 hours about ten amps 3. Electric toilet per person. In the evening before going to bed should be fully charged again. Typically, the engine or power generator is then charged in the morning until the consumption of the previous night is compensated. If the voltage drops to such a.
[PDF Version]Battery Charging On Board Ship. Batteries are one of the energy sources available on board vessels which are used in case of blackout and emergency situations on board a ship.
As a rule of thumb, if you motor for five hours or more a day at medium speed, you should – depending on the technical equipment of the yacht – have charged your batteries sufficiently (with about 250 amps, depending on the engine/alternator and batteries) to be able to use normal consumers on board for a while.
If properly calibrated, the battery 12.9V full charge. 12.5V 75 per cent charge. 12.2V 50 per cent charge. 12.0V 20 per cent charge. 11.8V battery flat. A slightly larger panel, connected via a regulator, will also replenish the batteries while the boat is not being used, such that each time you arrive at the boat they are already fully charged.
You have about 1/2 understanding of an on-board charger. An onboard charger is nothing more than a 1 bank (one battery), 2 bank (two batteries), or 3 bank (three battery) charger. It does not connect to the engine! It is powered by 120 volts AC power from a standard household outlet when at the dock or at home.
Depending on the battery type, this voltage/volt may be between 12.2 to 14.4 volts – value of the “full charge” of the batteries. After an hour of sailing or a swim stop, the voltage should be checked again to correctly estimate the voltage loss.
This voltage is about 14.4V for a low maintenance battery and 15.2V for a standard battery. The voltages are chosen to enable a full charge without significant gassing. Normally there is a selector switch so you can set the charger according to the type of battery.
How does a capacitor Fail?(1) Open failure, in which the resistance (impedance) of the capacitor reaches an extreme value(2) Short-circuit failure, in which the insulation is degraded and a DC current passes through(3) Failure in which capacitor characteristics such as capacitance and loss change significantly beyond specifications.
When a capacitor fails a short circuit (Figure 3), DC current flows through the capacitor and the shorted capacitor behaves like a resistor. For example, if a capacitor, placed between the input line and ground to remove AC current such as ripple current or noise, is shorted, DC current directly flows from the input to ground.
Mica and tantalum capacitors are more likely to fail in the early period of use (early failure), while aluminum electrolytic capacitors are more likely to experience wear-out failure due to aging use. In the case of film capacitors, when a local short circuit failure occurs, the shorted area may temporarily self-heal.
Capacitors fail due to overvoltage, overcurrent, temperature extremes, moisture ingress, aging, manufacturing defects, and incorrect use, impacting circuit stability and performance. Why Capacitor is Used? Why Do Capacitors Fail? What Happens When a Capacitor Fails? How Do You Know If Your Fridge Capacitor Failure Symptoms?
In the case of film capacitors, when a local short circuit failure occurs, the shorted area may temporarily self-heal. An open mode failure in a capacitor can have undesirable effects on electronic equipment and components on the circuit.
Power Failure: Capacitors are crucial for smoothing out voltage fluctuations in power supplies. A failed capacitor can lead to power failures or, in severe cases, damage to the power supply. Audio Noise: Audio equipment capacitors are used for signal coupling and noise filtering. Failure can introduce noise or distortions in the audio output.
High operating temperature is one reason that electrolytic capacitors are one of the most commonly failing components in electronics. Figure 4 shows how an electrolytic capacitor is constructed. Figure 4 – Electrolytic Capacitor Construction *If you are benefiting from The Tech Circuit, please consider donating HERE *
Typically, charging a lead-acid battery takes between 6 to 12 hours using a standard charging method, while fast charging can reduce this time to approximately 3 to 5 hours.
It takes 8 to 16 hours to fully charge a lead acid battery, depending on the size of the battery and the charging current. This applies to both AGM and lead acid batteries for cars.
The charge time of a sealed lead acid battery is 12–16 hours, up to 36–48 hours for large stationary batteries. With higher charge current s and multi-stage charge methods, the charge time can be reduced to 10 hours or less; however, the topping charge may not be complete.
The maximum charge rate for most lead acid batteries is about 10 amps per hour.
Lead acid batteries have some disadvantages, one of which is their long charging time. It can take 8 to 16 hours to fully charge a lead acid battery, depending on the size of the battery and the charging current.
A standard household charger cannot be used to charge a lead acid battery; doing so could damage the battery or even cause it to explode. However, if you have a lead acid battery and want to charge it quickly, it is possible, but you must follow the manufacturer's instructions for charging. Failure to do so could damage the battery or void your warranty.
To charge a 12V flooded lead acid battery, you should use 2.40-2.45 volts per cell as the charging voltage. This will ensure the fastest charge without damaging the battery.
How to Buy and Use Batteries Correctly?Regular Manufacturer The first thing to consider is the manufacturer. Reliability and Consistency Established battery manufacturers invest heavily in research and development to produce reliable and consistent products.
Picking the right battery Alternatively, you can look at the battery in your car itself. It should be clearly labelled, allowing you to check its specification and order the correct replacement. Many batteries will have a two- or three-digit designation, known as a group size, that is a standard provided by the Battery Council International.
Enter your vehicle details to search for batteries suitable for your car or van. Buy online and book an appointment for car battery fitting at your local Kwik Fit Centre at a time convenient for you. Our online prices include VAT and apply to retail customers only.
Our car battery buyer's guide will show you how to pick the correct replacement battery for your car, saving you both time and money. The main purpose of a battery is to provide the power to start the car and to power its features, such as the door locks and media system, when the ignition is off or in the accessory position.
There are online tools that can identify the battery you need according to your car's make and model, and even better, by your car's registration plate. Click here to use the battery finder tool. It will list all the battery sizes that fit your car. So, great. Now you have a list of batteries that will definitely fit your car.
It's important to select the right car battery because it ensures that your vehicle starts reliably and operates correctly. A battery that is too small or too large can cause problems with your car's electrical system. Please note: we are currently unable to complete battery bookings on hybrid/electric vehicles.
Car batteries aren't an optional extra - they do a few critical jobs within the car and you'd be left at a standstill without one! Starting - when you put your key in the ignition and give it that first half-turn to wake it up, your car battery is making that possible.
Unlike standard lithium-ion batteries, which can lose significant capacity and efficiency at low temperatures, these batteries are optimized to function in environments as frigid as -40°C.
A low temperature lithium ion battery is a specialized lithium-ion battery designed to operate effectively in cold climates. Unlike standard lithium-ion batteries, which can lose significant capacity and efficiency at low temperatures, these batteries are optimized to function in environments as frigid as -40°C.
Challenges and limitations of lithium-ion batteries at low temperatures are introduced. Feasible solutions for low-temperature kinetics have been introduced. Battery management of low-temperature lithium-ion batteries is discussed.
This study investigates long-term capacity degradation of lithium-ion batteries after low temperature exposure subjected to various C-rate cycles. Findings reveal that low temperature exposure accelerates capacity degradation, especially with increased C-rates or longer exposure durations.
LIBs can store energy and operate well in the standard temperature range of 20–60 °C, but performance significantly degrades when the temperature drops below zero [2, 3]. The most frost-resistant batteries operate at temperatures as low as −40 °C, but their capacity decreases to about 12% .
To counter the effects of cold weather, we recommend using high-quality lithium-ion batteries that are designed to perform well in extreme cold conditions. These batteries are specifically engineered to withstand low temperatures and deliver reliable power, even in freezing environments.
Proper storage of lithium batteries is crucial for preserving their performance and extending their lifespan. When not in use, experts recommend storing lithium batteries within a temperature range of -20°C to 25°C (-4°F to 77°F). Storing batteries within this range helps maintain their capacity and minimizes self-discharge rates.
Shut the circuit breaker off in your main electric panel.If you're not sure which circuit breaker your air conditioner is connected to, shut them all off. There may be more than one breaker involved. Make sure the power is off before working with any air conditioner. Take the door or cover off of your unit's control box and. You'll need to discharge the run capacitor and make it safe for further check up. Discharge the capacitor by using a very well insulated tool such as. If you have a dual-rated capacitor, you'll see three terminals marked Herm (short for “hermetic,” which indicates that the compressor is part of a hermetically sealed system), Fan (may. When you've checked everything out and you're sure that one or both of the capacitor's values are not near the appropriate requirements, it's necessary to change it. There are two.
One sends the initial jolt of electricity to start the unit while the other keeps the unit running. Newer AC units and heat pumps use a dual run capacitor or dual capacitor. This capacitor handles both the start and run functions. It essentially contains two capacitors in one canister. HVAC capacitors are measured in voltage and microfarads (MFD).
When replacing an old capacitor, the capacitance ratings on the new capacitor must EXACTLY match the ones from the old capacitor. For example, if your old capacitor was rated for 45/5 uF, then the new capacitor must have the same exact 45/5 uF rating. A dual-run capacitor also has a voltage rating. The voltage rating is either 370 VAC or 440 VAC.
A dual run capacitor helps your AC's compressor and condenser fan motor turn on. If your dual run capacitor goes bad, then one or both of these components won't turn on. A dual run capacitor is actually two capacitors combined into a single package – one capacitor is for your compressor, and the other is for your condenser fan motor.
AC Dual Capacitor Wiring: A dual capacitor combines both the start and run capacitor in one unit. The wiring is more complex but offers the benefit of a single component handling both tasks. Typically, the three terminals on a dual capacitor connect to the compressor, fan motor, and common wiring, each serving a specific function.
To test a dual run capacitor, you need to disconnect it from your AC unit, discharge the capacitor, and then use a multimeter to test it. Switch your multimeter to its capacitance testing setting and put the probes between the “COMMON” and “FAN” terminals to test the capacitance of the condenser fan side of the capacitor, as shown below.
A dual-run capacitor also has a voltage rating. The voltage rating is either 370 VAC or 440 VAC. The voltage rating on your new capacitor needs to meet or exceed the voltage of the capacitor that you're replacing. For example, if your old capacitor is 370 VAC, then you can use either a 370 VAC or a 440 VAC capacitor to replace it.