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How to fix circular light bulb? (aussie.zone)

submitted 4 months ago by [email protected] to c/[email protected]

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So, there's the circular bulb itself, and also this little removable plastic cylinder with two metal feet on it. How do I tell which of them needs replacing, and what specification to look for to know what to replace it with?

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[–] [email protected] 5 points 4 months ago (3 children)

The cylinder is called a starter, if you google for "halogen lamp starter" you'll find those. Essentially they charge up and then release a spark that ignites the gas inside the actual bulb. They are very inexpensive, so I'd start from there. Doesn't hurt to have a spare anyway.

If you unscrew it, the correct wattage should be written on the bottom between the prongs, just make sure you get one with the same rating so it works with your bulb. Feel free to post a picture of it and I can help search for one.

The prongs itself should be standardized, but the length of the starter may vary, so check if you can still close the lamp.

[–] [email protected] 4 points 4 months ago* (last edited 4 months ago)

Essentially they charge up and then release a spark that ignites the gas inside the actual bulb.

IIRC they pull power through the inductor and the electrodes in the tube, so the inductor has plenty of current running through it and the electrodes are hot, then suddenly break that circuit. The inductor makes the voltage across the tube spike super high and an arc forms inside the tube.

The little cylinder is the switch and capacitor at the bottom of the image. It starts off closed, so power goes through the tube's electrodes but not across the tube, then opens forcing power to go through the tube.

It's the rectangular bit that actually does the charging up.

[–] [email protected] 2 points 4 months ago (2 children)

Ah thanks! Frustratingly, Bunnings closes early on Saturdays, so I'll have to wait until tomorrow to actually go out and buy anything.

I think the last time it failed I bought a pack of two starters, and I managed to track down what I think is the second one that came with that (otherwise, it's the old old starter that I never threw away...) and put that in. It doesn't seem to have helped. I also noticed, which doesn't come across well in the posted photo, parts of the bulb are noticeably dark. Is that a good sign it might be burnt out?

[–] [email protected] 4 points 4 months ago* (last edited 4 months ago)

Dark spots means the tube is worn out and could definitely use replacing even if it did still work.

You might consider removing the whole thing and putting in an LED light instead.

[–] [email protected] 3 points 4 months ago

Yeah the dark patches on the tube are a sign that it's failed. If you get a replacement tube it would be worth trying it with the original starter (swap them back) to see if it still works.

[–] [email protected] 1 points 4 months ago

if you google for “halogen lamp starter” you’ll find those

Fluorescent starter, not halogen. Halogens don't have a starter so there is a chance you might get misdirected to halogen transformers.

(Unless you're talking big arc bulbs with halogens in them, they're fun)

[–] [email protected] 5 points 4 months ago (2 children)

Buy an LED oyster lamp of the same diameter and replace the whole thing.

Instant light, cheaper light, and no more bulb replacements required.

[–] [email protected] 2 points 4 months ago

Happy cake day!

Yeah that's what I ended up doing. Spent way too long in the store staring at the packet like an idiot, because the box said "use with LED replacement starter" but I couldn't figure out if said starter was included in the box or a separate purchase. After about 5 minutes of trying to figure it out I realised I could just open the box and see: yup, it was included.

I don't think they even still sell the fluoro type. The sell the starters aplenty, but not new bulbs.

[–] [email protected] 2 points 4 months ago

100% replace. Every time (three times) I've tried to deal with round fluro it was a major fuck around that didn't work out.

[–] [email protected] 4 points 4 months ago

Otherwise, wattage/lumens, colour and size are the main considerations. There are two sizes of the circular bulbs from memory? They generally come in cool white as well.

Your ballast might also have a max watt rating which would be written on there, but if you get an identical tube it shouldn't matter.

Depending on your situation you could consider an LED equivalent like this one. I recently changed mine after the ballast casing fell apart (it was really old) but I had to get a sparky out to rewire it. The upsides are slightly lower power consumption, LEDs last longer, instant on instead of flickering, and no need for a fluoro starter.

[–] [email protected] 3 points 4 months ago

I would take both the fluoro tube out and the starter and just go to Bunnings with them and get them to help pick the right replacements. They stock these in multiple sizes.

[–] [email protected] 2 points 4 months ago* (last edited 4 months ago)

If the lamp is flickering, like trying to ignite, but doesn't quite, its usually the starter. As the other post states, it's the cylinder thing. The cream thing is probably just the wiring bridge, which isn't involved aside from providing a connectionnto the mains. The white metal thingy is the ballast, doesn't usually need replacing. As LEDs replace the fluorescent tubes, you will find it harder to find parts, so you might just want to replace the whole fixture with something led based.