When AVR Power Supply Smells Like Burning Plastic?

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Purchase a High-Quality AVR

Voltage Regulator& Why?

A voltage regulator module (often abbreviated as "AVR") is an integrated circuit designed to precisely regulate the voltage supplied to other electrical components.

If you have a tendency to work with any electronic circuits or power supplies, you probably have heard or used this term already. AVRs are widely used in consumer electronics as a power supply regulator. And they are popular devices in low-voltage microcontroller based circuits.

It is recommended to use a high-quality AVR voltage regulator (from reputable brands) for many reasons. If you’re worried that it might be hard to detect whether your existing AVR voltage regulator is defective, don’t worry. You can use the following steps to test whether your AVR power supply is faulty or not.

How Does an AVR Work?

An AVR or automatic voltage regulator is a voltage regulator circuit that automatically regulates the output voltage to a desired value (usually adjustable). They can be used in power supplies to convert a non-regulated alternating current (AC) input at 220 or 110 volts to a constant direct current (DC), or they can be used as the main power supply in low power applications.

An AVR uses a concept referred to as feedback. The circuit monitors the output voltage of the power supply and compares it to the selected voltage. Based on this, the circuit adjusts the voltage to a constant value and the input voltage to another part of the circuit. AVRs are widely used in applications such as computers, printers, DVD players, scanners, and flashlights.

Why Does an AVR Smell Like It’s Burning?

The most common reason that an AVR smells like it’s burning is the presence of a faulty, or possibly defective, thermistor. Thermistors are resistors whose resistance changes when they are exposed to different temperatures. In an AVR, a thermistor is used as the sensor to provide a reference voltage that forms the basis of the control loop that regulates the output voltage.

Power Surges

And Outages?

A power supply, or a power supply unit (PSU), is an electrical device that converts AC (alternating current) electricity from a wall socket into low-voltage, direct current (DC) electricity. A surge protector is a device that is designed to protect your electronic devices from power surges.

A power surge is an increase in voltage, which is the measurement of potential energy per unit of charge. A power surge can cause your computer to malfunction, which can sometimes result in significant damage to your computer’s internal components.

There are two main types of power surges.

{1}. Instantaneous power surge
{2}. Spikes in voltage

An instantaneous power surge is a short, but severe, increase in voltage. Meanwhile, spikes in voltage can be the initial voltage during an instantaneous surge. A spike in voltage is characterized by its short length and duration.

A power supply generates electricity from an existing power source. But it’s not completely isolated from the outside world. This is why it is susceptible to disruptions and adverse conditions in the electrical current supplied by your utility company.

Power Outages

Many devices require a constant power supply to work properly. As the load on your appliances increases, you may find that your circuit breaker trips after a few moments. To keep the circuit breaker from tripping, you can either add an AVR fuse to the circuit or replace the circuit breaker with one that can support a higher load.

During a power outage, CFL bulbs may not work at all. This is because CFL bulbs require constant power to maintain the current working state. When the power is cut, the filament inside the bulb cools rapidly and reduces the resistance causing it to break. With this, the bulb goes dark.

If your AVR power supply smells like burning plastic, then there are a few things you can try. It’s important to know that whether you can identify the cause and the solution to the burning smell depends greatly on the device. The most important thing to do is to disconnect the AVR and then reconnect it to check whether the burning smell is gone. If it comes back once you reconnect the power supply, then you can consult a professional to ensure that the power supply is safe.

Quick-Start Feature

Is the power suddenly off during the kick-start?

If your AVR power supply suddenly turns off during the kick-start, turn off the power and unplug the power cord from the wall socket. Wait 10 minutes before turning the power on. The smell is the main cause of worrying, but there’s nothing to worry about. The power supply is perfectly safe. In the process of turning on the power, there could be a spark inside the power supply, and a small amount of burning plastic may be smelled. But this does not affect the normal use of the power supply.

Built-In Circuit Breakers

The AVR used in most consumer electronic devices is equipped with a built-in circuit breaker. The circuit breaker can be either internal fuse, or a thermal-reset circuit breaker, which will automatically trip without warning. In either case, this would be due to a short circuit, and in many cases, the short circuit may be the result of your own improper wiring.

The thermal-reset circuit breaker is similar to what you find in computers. It will trip if the temperature builds up beyond a certain threshold. The thermal-reset can be found in larger AVRs, and is usually triggered if no fan is installed in the AVR. You'd most commonly find this type of circuit breaker in higher power AVRs such as the microcontroller used in 6-axis controller boards for quadcopter drones. The thermal-reset circuit breaker allow these AVRs to take more abuse, compared to other consumer-grade AVRs, in order to be able to fly drones in very hot weather conditions.

What Should I Plug Into My AVR?

Atmel AVR chips are used to control millions of devices including TVs, washing machines, and microwaves. Software for AVR is written in the form of plain text and is easily editable using simple text editor. For this reason AVR so popular in hobbyist projects, including Arduino boards.

Unfortunately AVR chips have one major drawback. Once they reached working temperature, they tend to continue running for next 20-30 minutes. That’s typically enough time to cook a full meal. If you run AVR circuits on batteries, you will find that they hang even when the project is turned off.

The simplest solution is to always power your AVR circuit using an auxiliary power supply. This will bring your circuit to life and keep it in a low-power sleep mode when it’s not activated. The auxiliary power supply will be off whenever the AVR circuit is not being used, thus eliminating the risk of overheating.

Why The Burnt Plastic Smell?

If you smell an acrid burning plastic smell near your electronics, it is not safe to ignore. It may be the power supply on your amplifier or receiver. The power supply itself does not actually become warm or convert the voltage to electricity but instead, it provides a regulated output of DC electricity to power components inside the amp. To say it is a vital role would be an understatement.

As it converts and regulates the voltage, it creates heat during the process. Usually, it is cooled by a fan and it is normal for the power supply to get warm.

But when the burnt plastic smell is coming from the power supply it means something is going wrong. The smell may come from the power supply if the fan is clogged with dust or dead bugs.

You may also start to smell it if the fan is starting to fail. However, the burnt plastic smell is usually cause by the power supply’s capacitors. Capacitors are an important part of the power supply in that they remove any surges and noise from the voltage supplied by your wall outlet. They act like a buffer of sorts.

If the capacitor is failing it will start to smell like burnt plastic. This is not a good sign. You may need to replace the power supply if the problem continues.

Purchasing Tips

When there is an audible "pop" or "snap" after turning the power supply on, then the switching regulator on the AVR power supply has likely burnt out completely and is only good for a component donor or a testing item. They are inexpensive and many of them use the same part.

The switching regulator is replaceable, but it's usually not worth the time or expense to replace it.

Smell – Burnt Plastic

Since the power supply will often continue to operate after a single decoupling capacitor burns out, it is usually possible to narrow down which one is the source of the defect. If the decoupling capacitors in the power supply are tightly packed, it can be difficult to locate the bad capacitor.

The easiest way to test the capacitors is to quickly toggle the power supply's power switch. If the power supply has a built-in power switch, it will be found on the PCB. This will remove all the capacitors from the applied voltage and allow you to isolate the problem to the power supply or the main board.

The quick power switch test will not work if you have a modern power supply because most of them have a relatively large filtering capacitor in parallel with the main capacitor. The buck converter/driver needs this decoupling capacitor to function properly.

Let’s Sit Back and Enjoy the Show

If you wake up one morning and smell the distinct odor of burning plastic, then you can rest assured that your AVR power supply is in trouble. What you are smelling is actually the insulation material (fire retardant) around the transformer’s wires burning. Usually, the smell of smoke is a sign of impending failure.

This doesn’t mean your power supply is out of commission but it does mean you need to be extra aware of your AVR power supply. When an AVR power supply begins to smoke, it means one of two things – either you don’t have enough power to run your components – of a short circuit is building up inside the components and that the power supply is shutting it down. A short circuit usually means you’ve got a problem brewing.

A bulging or puffy power supply usually indicates a severe electrical problem. This is normally a very rare occurrence and you may just hear a fizzle and see sparks when it happens.

Try to use surge protectors in your home and equipment room to help prevent a short circuit.

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