• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Mini fluorescent light refuses to start.

RayRay1132

New Member
So, I recently purchased a pack of mini fluorescent lights (1.5 watts) each, and I noticed one of them had started to go dim, so I unplugged it and when I plugged it back in, it wouldn't start. The ends would just glow white, not the entire bulb. I then took apart the casing to see if anything was burned out and I noticed one of the two diodes connected to the PCB had a whitish gray covering over it. I opened up another one to see if it had the same thing and it didn't. Could that possibly mean the diode is bad. I didnt see anything else that could be possibly wrong, (start caps and resistors look fine)
Is there a way to see if a diode is bad by just looking at it. I left my multimeter at home and I'm on vacation.
 

gophert

Well-Known Member
Most Helpful Member
Try swapping the working and non-working bulbs. If the socket is bad, then it might be the diode. If the bulb is bad. Then try a new bulb.
 

Pommie

Well-Known Member
Most Helpful Member
A whitish grey covering does not sound like a blown diode. Could the tube have a leak and it's the fluorescent coating that's leaked?

Mike.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Have we fallen back through a time warp?, it's 2019 (last time I looked), LED lighting has long since replaced the crappy fluorescent tubes - why are you messing about with them still?.

Fluorescent tubes are incredibly unreliable, back when we used to use them at work it would be rare for a week to go by without replacing at least one.
 

gophert

Well-Known Member
Most Helpful Member
Have we fallen back through a time warp?, it's 2019 (last time I looked), LED lighting has long since replaced the crappy fluorescent tubes - why are you messing about with them still?.

Fluorescent tubes are incredibly unreliable, back when we used to use them at work it would be rare for a week to go by without replacing at least one.
Each week? Weird. Our maintenance guy only had to replace about 50 of them once per year.
 

DrG

Active Member
Have we fallen back through a time warp?, it's 2019 (last time I looked), LED lighting has long since replaced the crappy fluorescent tubes - why are you messing about with them still?.

Fluorescent tubes are incredibly unreliable, back when we used to use them at work it would be rare for a week to go by without replacing at least one.
I remember the noxious smell emitted by blown or blowing ballasts for those tubes - don't really know the circuitry but I guess I have good olfactory location abilities as I distinctly remember a group of us trying to discover the source of the noxious smell which I, eventually, uncovered and proved by correlating the decrease in odor intensity with turning the room light switch off. They were these sealed black box things and they did blow every so often, which I was subsequently able to recognize even walking down the hall as the odor was quite distinctive, if not unique.
 

unclejed613

Well-Known Member
Most Helpful Member
Fluorescent tubes are incredibly unreliable
and with modern hazmat regulations, expensive to clean up if one breaks.
They were these sealed black box things and they did blow every so often,
when i was young, they were potted with a heavy asphalt-like compound, which by itself had a nasty smell... add on top of that the smell of enameled wire burning.

but the OP is talking about small devices with an "electronic" ballast. my guess is the one that takes a long time to start has an open filament (assuming small lamps still use them, but TV backlight tubes still use filaments)... without the filament, the only way to start the tube is static electricity,
 

DrG

Active Member
.... they were CCFL, they NEVER used filament tubes. LED's replaced them a good while back though.
Not that it is terribly relevant, but I had a light board with a CCFL in it for photography. Something like this one https://www.vellemanstore.com/en/catalog/product/view/sku/FLPSW (I had it bookmarked from a few years ago). I really liked it but the illumination decreased with age. A time came when I thought I would replace it (which is where the link came from). Instead of doing that, I put in a string of white LEDs which someone had given me. It was a disaster - undoubtedly not LEDs that were appropriate for that use. I ended up putting the CCFL back. Instead of trying to fix it, I just ended up getting an LED light board. Been using it since and it works quite well. Of course the PWM dimming is problematic for photography, but at 100% it is great and it was quite economical.

Like I said, not terribly relevant :)
 
Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
Not that it is terribly relevant, but I had a light board with a CCFL in it for photography. Something like this one https://www.vellemanstore.com/en/catalog/product/view/sku/FLPSW (I had it bookmarked from a few years ago). I really liked it but the illumination decreased with age.
It's relevant in that it's the 'wear out' factor of florescent tubes (and CCFL's of course) - the phosphurs that create the visible light wear out over time, and it's this process which is used to predict the lifespan of the tube - the end of life is considered to be when the light output has dropped to a certain percentage of when it was new. The exact same process is used in Plasma TV as well, with the light output reducing as the set aged - unfortunately due to the way they work, the colour spectrum tends to change as well, and as they aren't very bright to start with the fading is noticeable (LCD has far greater brightness, so you can turn it up to compensate as it gets older.

On a related theme, while we're mentioning TV's, while I'm no longer in the TV trade I've still got a friend who is, and (as the TV repair trade is pretty well dead) I sub-contract some work to him. Anyway, he's been showing me the current problems, particularly with LG TV's (although Samsung and others are affected).

All LCD sets are back or edge lit, now using LED's - and LG have produced a much cheaper panel type using very few LED's for back lighting, and each SM LED is soldered to a flexible tape, and has a reflector/disperser lens glued over it. First problem is less LED's means much higher currents, and the LED's are dying in droves, with the overheating causing them to go purple rather than white - rather ruining the quality of the picture. Even worse, the lenses fall off the LED's, giving bright areas on the screen with darkness round them (REALLY ruining the picture) - you can hear them rattling round the bottom of the screen when you move it.

So BIG problems now with LG, Samsung and other makes of TV's.
 

tvtech

Well-Known Member
Most Helpful Member
It's relevant in that it's the 'wear out' factor of florescent tubes (and CCFL's of course) - the phosphurs that create the visible light wear out over time, and it's this process which is used to predict the lifespan of the tube - the end of life is considered to be when the light output has dropped to a certain percentage of when it was new. The exact same process is used in Plasma TV as well, with the light output reducing as the set aged - unfortunately due to the way they work, the colour spectrum tends to change as well, and as they aren't very bright to start with the fading is noticeable (LCD has far greater brightness, so you can turn it up to compensate as it gets older.

On a related theme, while we're mentioning TV's, while I'm no longer in the TV trade I've still got a friend who is, and (as the TV repair trade is pretty well dead) I sub-contract some work to him. Anyway, he's been showing me the current problems, particularly with LG TV's (although Samsung and others are affected).

All LCD sets are back or edge lit, now using LED's - and LG have produced a much cheaper panel type using very few LED's for back lighting, and each SM LED is soldered to a flexible tape, and has a reflector/disperser lens glued over it. First problem is less LED's means much higher currents, and the LED's are dying in droves, with the overheating causing them to go purple rather than white - rather ruining the quality of the picture. Even worse, the lenses fall off the LED's, giving bright areas on the screen with darkness round them (REALLY ruining the picture) - you can hear them rattling round the bottom of the screen when you move it.

So BIG problems now with LG, Samsung and other makes of TV's.
Were seeing it here too (even though I know zilch about flat screens). The guy trying to fix them is :(

So I soldier on. And learning about flat screens now. I'm not impressed. Plasma no spares. IGBT was designed for Plasma. Guess what...IGBT not available here. Only fakes that don't work.

So I try and help here. I'm the only one that can understand a datasheet and it's specs. Others here have problems even understanding resistor codes...........

Oh well, as long as I have food to eat I mustn't complain.
 

Latest threads

EE World Online Articles

Loading

 
Top