Replacing capacitors in CFLs (compact fluorescent lamps)

[WindWalker]

Hi,

I’ve been repairing CFLs and had to replace the capacitors (failed by short-circuit) between the two tube filaments of each lamp. Here you can see schematics to understand which capacitor I’m talking about: http://www.pavouk.org/hw/lamp/en_index.html#schematics_and_photos (the tube filaments are usually identified as LMP1 and LMP2).

The capacitors are long (“vertical” in relation to the PCB holes, not “horizontal”) and flat, the color seems to be dark green/very dark brown/black (not sure… maybe they get darker from heating during use). From my research, it seems they are 'polyester film' capacitors.

The capacitors I replaced in the two CFLs had this identification:
1)
3N
3n3J

2)
332J
N1K0 (not sure if the last character is zero or letter O)

I understand that both capacitors are 3.3nF 5% tolerance (letter J), so I replaced both capacitors with 3.3nF 1.2kV capacitors of the same type and also being used in CFL ballasts with the same function (capacitor between filaments) — the goal was to get working CFL lamps by using only salvaged parts instead of buying new ones.

My issues are:
i) Would the lower voltage rating for capacitor 1 replacement be an issue? I ran the lamp for at least 30min-1h and it seems to be working fine (maybe the higher rating is only to better withstand lamp startup transients?). The lamp is a PHILIPS Tornado Esaver 23W.

ii) What is the voltage rating of capacitor 2? I can’t understand from the inscription, but the lamp also seems to be working fine after capacitor replacement. The lamp is a PHILIPS Genie 18W.

Thanks

[andy3055]

That should be a 220pF capacitor. See below link for other relevent info:

https://www.electronics-tutorials.ws/capacitor/cap_5.html

[WindWalker]

I don't understand how you concluded they are 220pF capacitors. Did you see the schematics on the website that I linked? What I've seen in CFL ballasts for capacitors with this function are values typically between 2.2 and 4.7nF. Also, 332 means 3.3nF according to a table on the website you linked.

I followed these code tables, which have similar information.

[andy3055]

Ah! I was referring to the image (Bigluz) and your question "ii) What is the voltage rating of capacitor 2?" That diagram lists it as 220J/100v Which means it is a 220pF/100volt capacitor the letter J denotes a tantalum according to the site I referred.

Since you have several diagrams, it may be easier for you to list the parts so someone can help. If not, we will be going in circles.

[T3sl4co1l]

220J should be 22p, 221 would be 220p.

Color banded dipped tantalums... man, that's a trip back in time.  Literally only place I've seen those is in my 1973 vintage Tektronix 475.

Needless to say, anything of that sort will not be found in a CFL.

OP: the problem with repairing CFLs is, the tube and the electrolytic age at a similar rate.  Ideally they're made to fail at the same rate.  There's a few cents worth of light left in the thing, after one of the two electronic components has failed.  Whether that's enough to justify repairing them in your part of the world, I don't know, but it strains the imagination in most parts?

And if you're so strapped for resources that repairing CFLs looks attractive -- where are you getting replacement parts from?  If you're salvaging them from other CFLs, well... y'know?  What did they die of, and how much life do they have left?  If you're ordering parts, why not just get brand new things, especially LEDs these days?

Tim

[andy3055]

"220J should be 22p, 221 would be 220p."

You are correct. Sorry for my lapse.

[james_s]

I repaired quite a few CFLs 10+ years ago but since I started upgrading to LEDs in 2011 I have no use for CFLs anymore, I got tired of waiting for the remaining ones to fail and gave them all away along with my remaining spare stock. CFLs are obsolete.

[WindWalker]

Ah! I was referring to the image (Bigluz) and your question "ii) What is the voltage rating of capacitor 2?" That diagram lists it as 220J/100v Which means it is a 220pF/100volt capacitor the letter J denotes a tantalum according to the site I referred.

When I wrote 'capacitor 2', I meant the second capacitor in my first post (3N 3n3J), not C2 in the schematics.

The capacitors I've replaced are the ones between tube filaments, like this one (highlighted in purple):

OP: the problem with repairing CFLs is, the tube and the electrolytic age at a similar rate.  Ideally they're made to fail at the same rate.  There's a few cents worth of light left in the thing, after one of the two electronic components has failed.  Whether that's enough to justify repairing them in your part of the world, I don't know, but it strains the imagination in most parts?

And if you're so strapped for resources that repairing CFLs looks attractive -- where are you getting replacement parts from?  If you're salvaging them from other CFLs, well... y'know?  What did they die of, and how much life do they have left?  If you're ordering parts, why not just get brand new things, especially LEDs these days?

I have (free) access to CFLs that would otherwise end up being recycled, sometimes I find more than one lamp of the same exact model, so it's relatively easy to find suitable replacement parts. I've even found CFLs and LED lamps that were trashed but worked without any apparent problem

Sure, time/money-wise it is not worth doing this (the two last GU10 5W LED lamps I bought have cost me less than US$3). I did this mostly for fun/the instructive side of things: didn't even know capacitors could fail by short circuit or that I could measure ESR using a function generation and oscilloscope (https://youtu.be/115erzCCxgE). I'm not doing this to make ends meet or anything like that.

Also, problems with the electrolytic capacitor or upstream (bridge rectifier, fuse resistor) are fairly easy to diagnose, I don't think I would create a topic for that.

CFLs are obsolete.

I agree, but that's not what I was looking for as an answer when I created the topic.

[james_s]

Well at any rate that film capacitor between the cathodes being shorted is precisely the problem I found in at least a dozen or so lamps back in the day. The film dielectric is extremely thin and combined with the relatively high temperature and high voltage they are subjected to along with the fact that most of these lamps were made as cheaply as possible, is a recipe for failure. The two usual faults with film caps is they either short, or the capacitance gradually falls as shorts blow away a spot of metalization, or they short badly enough that they can't self heal.

[T3sl4co1l]

EPCOS/TDK even produce capacitors made specifically for this purpose: the breakdown is not only intended, but specified, in terms of capacitance decrease (due to self-healing) versus number of starts.  That's how they're so small.

Tim

[SilverSolder]

I find the hardest part of fixing CFLs to be opening the blasted things...

There's a couple of nice 50W CFLs in the garage (bright!)...   they lasted 15 years before one of them stopped working.  I couldn't figure out how to open it without resorting to extreme violence which basically readied it for recycling...

[WindWalker]

I find the hardest part of fixing CFLs to be opening the blasted things...

You just need a slot head screwdriver and some patience. The wider and thinner the slot head, the better. No brute force is needed. Searching for 'open cfl bulb' on Youtube will give you this:
1) https://youtu.be/DTAPCzYYf-o?t=75
2) https://youtu.be/EuBebYqypxk?t=50

[james_s]

Some of them were much easier to open than others, but the cheap ones normally just snap together. You do have to be careful not to stab yourself in the hand or break the tube if your screwdriver slips.

[SeanB]

Those film capacitors start out a nice green, or a light brown, but with time and being cooked inside the lamp, turn black.

For me I used to repair them, in the days that a CFL lamp was a $20 item, which was when they first started to become a thing. Those often also used a replaceable PL lamp in them as well, so you could replace the EOL lamp, and re use the electronics module. Thus they used TO220 transistors, and had typical failures being the bridge rectifier diodes failing, along with the electrolytic capacitor ( 4u7 450V) and the 10R fusible resistor.

Still have a couple that are magnetic ballasted, meant to be used with a 2 pin PL6-13 lamp, with integrated starter. those were in use 24/7/365 for a decade, and still work, though the lamps themselves would need changing pretty much as an annual thing, at least they actually were meeting the manufacturer (in general Phillips, Osram and GE, all made in the EU) spec of a 10k hour lifetime. the cheaper lamps barely made 1000 hours, and the nastiest ones did not even last a week.

[grizewald]

I was very happy when I replaced the last CF lamp in my house with an LED version.

Finally, I can read the colour bands on resistors again and I don't look a sickly green all the time.

Death to CFL!!!

[james_s]

I actually had pretty good luck with the lifespan of even the inexpensive CFLs. A percentage of them had infant mortality but once they got past that I was regularly getting 6000-8000 hours out of the heavily used ones. The key to long life with a fluorescent lamp, especially the instant start variety is minimizing starts. Every time you start it small bits of oxides are blasted off the cathodes, especially if you do so via brute force instead of first preheating them. In my outside lights that are on timers and photocells that run them from dusk till dawn and in a few inside lights that tend to be turned on when I get home and turned off when I go to bed I was getting at least the rated life out of the coily CFLs.

Once good LED lamps came out I started upgrading CFLs to those as they burned out. Eventually I got tired of waiting and as prices on LEDs dropped I changed out the rest of the CFLs and gave them away. Since then changing bulbs has become a thing of the past, I can turn them on and off as much as I like without feeling like I'm murdering the bulbs and for things like bathrooms and closets the bulbs aren't just approaching full brightness when I'm ready to shut them off.

[wraper]

I was very happy when I replaced the last CF lamp in my house with an LED version.

Finally, I can read the colour bands on resistors again and I don't look a sickly green all the time.

Death to CFL!!!

That purely depends on what CFL and what LED. You can buy both types with good and crappy CRI.

[james_s]

That purely depends on what CFL and what LED. You can buy both types with good and crappy CRI.

Yes although high-CRI CFLs were never very common, at least not around here. At the local stores pretty much everything was 80 CRI.

The big advantages of LEDs for me was instant on to full brightness, good dimming and long life even with short cycles. They're a lot more physically durable too which is beneficial in some applications.

[wraper]

and long life even with short cycles.

Again depends on bulb. Regardless on what's written on the package, you can buy CFL or LED bulb which will last only a few months. With CFL you can at least expect they are built with about the same type of ballast. With LED, it's a crapshoot. It can be capacitive dropper, linear regulator IC or proper high efficiency converter.

[james_s]

Again depends on bulb. Regardless on what's written on the package, you can buy CFL or LED bulb which will last only a few months. With CFL you can at least expect they are built with about the same type of ballast. With LED, it's a crapshoot. It can be capacitive dropper, linear regulator IC or proper high efficiency converter.

You won't find a CFL bulb that tolerates short cycling without a reduction in life, or that achieves full brightness instantly, those traits are limited by physics.

Yes you can get garbage LED bulbs, but a good quality LED bulb will beat the best quality CFL you will find in every measurable aspect. The best LEDs offer longer life, higher CRI, higher efficiency, faster to full brightness, and better dimming performance than the best CFLs ever developed. There is no such thing as a CFL that does 90+ CRI, 80+ lumens per watt, 50k hour life, dimming down to 2%, instant on to full brightness that can tolerate dozens of starts per day and still last the rated life. Such a thing doesn't exist and never has.

[grizewald]

I remember when buying my first CFLs that they were stating 10,000 hours life guaranteed on the packaging. About three months later I found myself wishing I'd kept the packaging and receipts so that I could take all the dead ones back to the store and get my money back.

This has to be one of the biggest marketing scams of the time. By the time most of them failed, you could almost be certain that the buyer had no way of proving when they were bought and first installed and certainly wouldn't have any receipts or if they did, would have no way to link each lamp back to its receipt.

When some of them gave up the ghost, they did it in such an explosive manner that they often tripped the breaker in my apartment's distribution panel. Even worse, one of them not only tripped the breaker in my panel, it actually blew the 20A fuse in the main panel in the locked room in the basement of the apartment block! If it wasn't for the fact that by pure coincidence there was a guy from the electricity company working in the next block that day, I would have been stuck in the dark at home while desperately trying to get hold of someone to come and change it while the contents of my freezer started to melt!
 

[james_s]

I wouldn't consider it a scam exactly. If you read the fine print it will specify things like "based on 5 hours per start", base down, not for use in enclosed fixtures, etc. If you turn on a CFL and let it run continuously until it burns out you will easily achieve the full rated life on most samples. The problem is that most people do not run the lights in their house 24 hours a day, and most are not even turned on once, run for hours and then turned off. In the real world lights get turned on and off numerous times a day and this murders CFLs, that alone is one of the biggest advantages of LEDs, you can turn them off and on twice a second all day long and they don't care.

[SilverSolder]

Are there LED replacements that pump out as much light as my ancient 50W (real power) CFLs?  -  and do they do it in a nice spherical pattern like a CFL?

[james_s]

I have not looked for such a beast but I'm sure they exist. There are screw-in LED replacements for 400W metal halide lamps so replacing a 50W CFL should not be a problem. That's quite a niche application though, there are few domestic applications for such large lamps and commercial/industrial applications like that would normally be HID or linear fluorescent. Most LED lighting for those same applications consists of integrated fixtures that do not have separate lamps.

[Zero999]

Still have a couple that are magnetic ballasted, meant to be used with a 2 pin PL6-13 lamp, with integrated starter. those were in use 24/7/365 for a decade, and still work, though the lamps themselves would need changing pretty much as an annual thing, at least they actually were meeting the manufacturer (in general Phillips, Osram and GE, all made in the EU) spec of a 10k hour lifetime. the cheaper lamps barely made 1000 hours, and the nastiest ones did not even last a week.

I remember when my parents got one of the early retrofit CFLs, sometime in the 80s. It took awhile to warm up and flickered, when starting. After it failed, I opened it up to see what was inside. It had a magnetic ballast and glow starter. The tube wasn't replaceable and was concealed inside a glass diffuser.