How do you replace a broken LED driver?

Read the label of the old driver and look for a new one with the same kind of output: the same current in milliamps for a constant-current driver, or the same voltage for a constant-voltage driver. The power may be equal or slightly higher, and if the old one was dimmable, the new one must be too. Then move it across wire by wire.

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Is it really the driver?

An LED rarely fails all at once. It slowly gets dimmer over thousands of hours. What does give up suddenly is the electronics in front of it. That is also covered in Can you replace an integrated LED? A few signs that the driver is the culprit:

• One spotlight is off while the rest on the same switch are on, and each spotlight has its own driver.
• A whole row of spotlights goes out at once, while they hang on one shared driver.
• The spotlight flickers, only comes on after a few seconds, or goes off when it gets warm.

The surest test: swap the driver with that of a spotlight that does work. If the problem moves with it, it is the driver. If it stays with the same spotlight, it is the LED.

Constant current or constant voltage

Every label shows an input and an output. The input is mains voltage, 220 to 240 volts. At the output you see one of two things:

A current in milliamps, for example 350 mA, and a voltage range. That is a constant-current driver. It holds the current steady and lets the voltage follow the number of LEDs. Most recessed spotlights with built-in LED work this way. Replace it with a driver with exactly the same current, whose voltage range covers that of the old one. A 700 mA driver on 350 mA LEDs pushes twice too much current through them; those LEDs will not survive it for long.

A fixed voltage, usually 12 or 24 volts. That is a constant-voltage driver, such as a power supply for 12 volt spotlights. Here the voltage must be the same, and the power may be higher than what the spotlights draw together.

Never mix them up. A voltage driver on a spotlight that expects current, or the other way round, either does not work or destroys it.

Calculating with power

Add up the wattage of all the spotlights on the driver and keep a margin. Our 20 watt 12 volt driver is meant for at most six spotlights of 3 watts. Six times 3 is 18 watts, and that is already close to the maximum. A driver that always runs fully loaded does not last as long. The 40 watt version takes ten.

Note: those two are for 12 volt spotlights. They do not belong on a 230 volt fixture. More about the difference is in Which LED driver do you need?

Dimmable or not

If the old driver was on a wall dimmer, the new one must also be dimmable, with the same type of dimming. The label then often says Triac or trailing edge. A non-dimmable driver on a dimmer flickers or fails. Our 12 volt drivers do not dim from the wall but with a remote control that comes with them, so no wall dimmer belongs with those.

The replacement

Circuit off and measure. See How do you check that the power is off?

Pull the spotlight out of the ceiling and get hold of the driver. Hold the springs, they snap back.

Take a photo of both sides. The mains side with live, neutral and possibly earth; the LED side with plus and minus, or with a small plug.

Move the mains side across, then the LED side. With a small plug: if it does not fit, it is probably not the right driver either.

Lay the driver dry and clear, not under insulation. Circuit on and test.

No matching driver to be found?

Some fixtures have a driver with its own plug or a rating you cannot find separately. Then a new fixture is often quicker and cheaper than searching on. If the new spotlight fits the same hole, it is a quarter of an hour's work. All models are in recessed spotlights.