Buzzing transformer on Christmas lights

[MyNameIsUrl]

Is there any way to stop the transformer on my lights buzzing? It works fine, doesn’t get hot, is 1 year old. But the noise is annoying. Doesn’t look like it will open up unless it’s broken into.

Or can I replace it? It’s 24v 850ma which means that none of the dozen or so spares that I’ve accumulated over the years matches it for voltage. It’s not hard-wired to the lights but has a 5mm hole in it with a pin inside.

[GoSeigen]

You can replace it, but make sure the following all apply to the new power supply:
1. The output voltage is the same, to within about 10%.
2. The max output current/power rating is at least as high: more than 850mA or about 20W.
3. The polarity of the output connector matches the original. You might need to test which was the positive terminal (the internal pin or the metal surround) and ensure that the new one is the same. If not, and you are adept with a soldering iron, you could reverse the wires.

Additionally, if the lights are LEDs, your new adaptor may not be suitable: there are various outcomes in this case, from working 100% to destroying the LEDs fairly quickly -- your risk.


Of course, if you bought the lights recently you might be able to return them to the retailer...


GS
EDIT: P.S. 24V is a fairly common Windows laptop power supply voltage IIRC. A friend might have an unused one knocking about...

[eepee]

I take it that (as is the norm these days), the two halves of the adaptor are not screwed together?

If they are, there may be a solution.

Regards,
ep

[MyNameIsUrl]

I take it that (as is the norm these days), the two halves of the adaptor are not screwed together?

Correct, no screws. There is a joint line which looks glued. I could have a go at cutting through it, but don't want to render the whole thing unusable especially as the lights are up on the gutter.

I'm unable to find a replacement online, so I may just have to turn the lights off when the noise is too much, and replace the whole thing next year.

[eepee]

No, don't open it because it could be that the buzzing is not what I think it might be and thus unrepairable.

Press on it in various ways and see if the buzzing stops.

If it does and you have a suitable clamp, clamp it as you found out it 'works'. After all, it is only going to be on for a few days.

If you do clamp it, probably best if it is running from an extension cable on the floor. I don't think you should clamp it when running off a wall socket because of the xtra weight.

Regards,
ep

[gryffron]

Is it a transformer? Very heavy? Almost solid metal.

That would be very unusual these days. Normally it is a switched mode power supply. Very light. If it is buzzing, it is faulty. They normally run at above 20kHz. Beyond normal hearing. No way it should produce a mains hum.

Gryff

[MyNameIsUrl]

Press on it in various ways and see if the buzzing stops.

If it does and you have a suitable clamp, clamp it as you found out it 'works'. After all, it is only going to be on for a few days.

Yes, squeezing the sides does quieten it considerably. What's going on here - I have a basic understanding of a transformer - is it a flexible piece of metal which is under the influence of the alternating magnetic field which is touching the side of the case? The fact that you knew about it suggests it's a very common problem.

Is it a transformer? Very heavy? Almost solid metal.

That would be very unusual these days. Normally it is a switched mode power supply. Very light.

Yes, very heavy. It's only 2 years old, modern led lights but old fashioned transformer. I thought they would last a few years, but apparently not. £50 a set unfortunately.

[kempiejon]

Is there any way to stop the transformer on my lights buzzing? It works fine, doesn’t get hot, is 1 year old. But the noise is annoying. Doesn’t look like it will open up unless it’s broken into.

Or can I replace it? It’s 24v 850ma which means that none of the dozen or so spares that I’ve accumulated over the years matches it for voltage. It’s not hard-wired to the lights but has a 5mm hole in it with a pin inside.

Like this 'un? https://www.amazon.co.uk/20-4va-Adaptor ... B00603W43W

[csearle]

Yes, squeezing the sides does quieten it considerably. What's going on here - I have a basic understanding of a transformer - is it a flexible piece of metal which is under the influence of the alternating magnetic field which is touching the side of the case? The fact that you knew about it suggests it's a very common problem.

Sounds like a good old-fashioned transformer, especially as the thing is heavy. Nothing very flexible in a transformer. Dense chunk of laminated metal slices stuck together with some windings of varnished wire wrapped tightly around them. The things will want to vibrate. If you can hear it humming away then it will be moving and thus causing the sound. As squeezing it makes it quieter then it is probably vibrating the enclosure. Doesn't sound particularly unsafe to me. If you can put up with the noise then do so, if not get some kind of replacement. A switched-mode power supply as described by others will be quieter but will likely be less reliable because of its added complexity. It still may outlive all of us mind you.

Chris

[GoSeigen]

Yes, squeezing the sides does quieten it considerably. What's going on here - I have a basic understanding of a transformer - is it a flexible piece of metal which is under the influence of the alternating magnetic field which is touching the side of the case? The fact that you knew about it suggests it's a very common problem.

The case probably resonates at a similar frequency to the electrical current, either through wear and tear or poor design in the first place. I agree there's not much harm in clamping it or otherwise dampening the vibrating areas to reduce the noise. Just be careful not to substantially reduce its ventilation.

GS

[eepee]

I remember doing a presentation some years ago, with equipment given to me, at a remote location.

When switching on a device. its wall-plugged adaptor buzzed but I discovered that squeezing it did stop the buzzing.

The only grip that the caretaker (I think it was) could come up with was a rusty, very heavy, probably cast iron, F clamp about two feet long.

To see that contraption on a short extension lead, on the floor in what was a fairly bare smallish room for a ''latest technology' technical presentation did cause quite a bit of merriment making it a great ice-breaker for what was to come.

Regards,
ep