Replacing capacitors in CFLs (compact fluorescent lamps) - Page 1
Forum section: electronics / repair

author: WindWalker
author_rank: Contributor
timestamp: April 09, 2020, 03:17:41 am
content: 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)3N3n3J2)332JN1K0 (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

author: andy3055
author_rank: Super Contributor
timestamp: April 09, 2020, 03:28:33 am
content: That should be a 220pF capacitor. See below link for other relevent info:https://www.electronics-tutorials.ws/capacitor/cap_5.html

author: WindWalker
author_rank: Contributor
timestamp: April 09, 2020, 03:41:48 am
content: 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 thesecode tables, which have similar information.

author: andy3055
author_rank: Super Contributor
timestamp: April 09, 2020, 03:57:24 am
content: 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.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 09, 2020, 04:10:01 am
content: 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

author: andy3055
author_rank: Super Contributor
timestamp: April 09, 2020, 04:51:23 am
content: "220J should be 22p, 221 would be 220p."You are correct. Sorry for my lapse.

author: james_s
author_rank: Super Contributor
timestamp: April 09, 2020, 04:55:04 am
content: 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.

author: WindWalker
author_rank: Contributor
timestamp: April 10, 2020, 01:56:20 pm
content: Quote from: andy3055 on April 09, 2020, 03:57:24 amWhen 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):Quote from: T3sl4co1l on April 09, 2020, 04:10:01 amI 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 problemSure, 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.Quote from: james_s on April 09, 2020, 04:55:04 amI agree, but that's not what I was looking for as an answer when I created the topic.

author: james_s
author_rank: Super Contributor
timestamp: April 10, 2020, 04:39:22 pm
content: 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.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 11, 2020, 06:38:01 am
content: 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

author: SilverSolder
author_rank: Super Contributor
timestamp: April 11, 2020, 10:32:05 am
content: 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...

author: WindWalker
author_rank: Contributor
timestamp: April 11, 2020, 04:56:29 pm
content: Quote from: SilverSolder on April 11, 2020, 10:32:05 amYou 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=752)https://youtu.be/EuBebYqypxk?t=50

author: james_s
author_rank: Super Contributor
timestamp: April 11, 2020, 06:45:14 pm
content: 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.

author: SeanB
author_rank: Super Contributor
timestamp: April 11, 2020, 07:35:04 pm
content: 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.

author: grizewald
author_rank: Frequent Contributor
timestamp: April 11, 2020, 07:42:42 pm
content: 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!!!

author: james_s
author_rank: Super Contributor
timestamp: April 12, 2020, 12:44:10 am
content: 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.

author: wraper
author_rank: Unknown
timestamp: April 12, 2020, 01:07:24 am
content: Quote from: grizewald on April 11, 2020, 07:42:42 pmThat purely depends on what CFL and what LED. You can buy both types with good and crappy CRI.

author: james_s
author_rank: Super Contributor
timestamp: April 12, 2020, 02:40:41 am
content: Quote from: wraper on April 12, 2020, 01:07:24 amYes 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.

author: wraper
author_rank: Unknown
timestamp: April 12, 2020, 02:50:26 am
content: Quote from: james_s on April 12, 2020, 02:40:41 amAgain 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.

author: james_s
author_rank: Super Contributor
timestamp: April 12, 2020, 02:57:07 am
content: Quote from: wraper on April 12, 2020, 02:50:26 amYou 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.

author: grizewald
author_rank: Frequent Contributor
timestamp: April 12, 2020, 07:29:40 am
content: I remember when buying my first CFLs that they were stating 10,000 hours lifeguaranteedon 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!

author: james_s
author_rank: Super Contributor
timestamp: April 12, 2020, 07:36:53 pm
content: 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.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 12, 2020, 07:44:44 pm
content: 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?

author: james_s
author_rank: Super Contributor
timestamp: April 12, 2020, 07:51:27 pm
content: 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.

author: Zero999
author_rank: Super Contributor
timestamp: April 12, 2020, 10:28:09 pm
content: Quote from: SeanB on April 11, 2020, 07:35:04 pmI 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.

author: james_s
author_rank: Super Contributor
timestamp: April 12, 2020, 10:42:49 pm
content: Quote from: Zero999 on April 12, 2020, 10:28:09 pmThat sounds like the Philips SL series. I had one that a Philips rep gave to me when I was a kid and went to a lighting trade show with my dad. I still have a European SL grow light which is the same thing with a half reflectored glass globe instead of the jar style diffuser.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 12, 2020, 11:59:33 pm
content: Quote from: james_s on April 12, 2020, 07:51:27 pmThe ones I use are reminiscent of these:https://www.1000bulbs.com/product/1604/FC55-FEUS55W27.html3600 lumen. I haven't measured mine, but two of those really do light the garage up properly... just don't look directly at them!I'm not sure that LED is competitive for this specific application?Here is a 400W equivalent CFL :https://www.lightbulbs.com/product/eiko-81180/The prices seem very keen compared with similar power LED. Perhaps there is still a sweet spot for CFL at this power level?

author: james_s
author_rank: Super Contributor
timestamp: April 13, 2020, 12:11:08 am
content: It may be, I don't really know. LED "bulb" development has been centered around the common 60W household bulb on one side at around 800 lumens and large HID lamps on the other in the range of 20,000 lumens for things like lowbay and streetlighting retrofits. Those big CFLs are kind of in the middle between the two categories. There are some like thishttps://www.amazon.com/WOOPHEN-Daylight-Factory-Warehouse-Backyard/dp/B07DQC38CGbut I can't speak for the quality, a lot of those "corncob" types are fairly crappy and if you just stick one in a bare socket it will be a glare bomb.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 13, 2020, 01:24:19 am
content: Thanks for the link, those ones do look comparable to the big CFLs. When the next one blows, I might give something like this a try.

author: Zero999
author_rank: Super Contributor
timestamp: April 13, 2020, 08:55:48 am
content: Quote from: james_s on April 12, 2020, 10:42:49 pmYes. I had a Google and most of them seemed to have prismatic diffusers. This one was painted, rather than prismatic and looked like this.https://www.lighting-gallery.net/gallery/displayimage.php?album=1801&pos=0&pid=52903

author: james_s
author_rank: Super Contributor
timestamp: April 13, 2020, 05:26:37 pm
content: I think I have one like that somewhere, except a 120V model with an ES base.I know I have one of thesehttp://lamptech.co.uk/Spec%20Sheets/D%20FLCi%20Philips%20SL18R.htmIt's rated 220V 50Hz although it actually lights up almost as bright on 120V 60Hz IIRC.The prismatic type is what I had when I was a kid.http://lamptech.co.uk/Spec%20Sheets/D%20FLCi%20Philips%20SL18%20Mk2%20Prismatic.htm

author: Vincenzo
author_rank: Regular Contributor
timestamp: September 04, 2023, 01:43:21 am
content: The way that this beautiful electronics question from the OP (in an electronics forum - the best out there) turned into merchandise preference of random people from around the world is bizarre to say the least.I am trying to repair the "electronic ballast" which is what this circuit is called (as opposed to the old choke ballast) of my favorite table lamp-magnifier and found that it only had a handful of through hole components on a single layer PCB, so I tested all the components and made a daveCAD sketch of the circuit which looks like the ones that the OP made. The only faulty component I found was the cap between the two filaments which in my case was a 6n8 (682) and 1.2KV (1k2) which is OPEN!I opened two regular (curly) CFL bulbs and found both having 4n7, 1.2kv caps. I'll probably put one of them in place of the 6.8 original one. My question is did anyone do that before (OP) and is there any danger?I did some reading and found a cool paper that describes the circuit and that the two filaments and two caps are in series but the smaller cap helps with starting (when it has most of the voltage which is up to 1200v because it is about 1/10 of the larger one which in my case is 47n). This is the paper I found:https://www.st.com/resource/en/application_note/an527-electronic-fluorescent-lamp-ballast-stmicroelectronics.pdf

author: Vincenzo
author_rank: Regular Contributor
timestamp: September 04, 2023, 11:06:24 pm
content: Update: replaced the 6n8 with a 4n7 from a cheap bad cfl bulb and it's working!then tried the old circular bulb that had a little bit of darkness near one of its ends and it blinked, so i tossed it and put the new bulb (about $10 at home depot).i always thought that those nano value green caps are more in audio applications and that they are almost always rated at 100v, but these are 1200v and not available on digikey, ebay, ...etc, and i have a feeling that even if they are found, the price is probably going to relatively high. I'll start taking salvaging parts from old CFLs and ballasts more seriously from now on.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 05, 2023, 01:05:18 pm
content: Not sure about the green ones specifically, but there are caps on DK rated for CFL use. Have seen the plots of lifetime and self-healing in EPCOS/TDK datasheets several times. Those were usually boxed PP types that I was looking through.There's nothing special about them, indeed they'reworse, in a very particular and intentional way. They're designed to fail, minimizing size and cost in an extremely cost-sensitive mass-production application. The challenge is achieving maximal cycles, while ensuring self-healing proceeds only gradually until total failure; and this is reflected in the qualification and characterization testing shown in the datasheet.A reliable replacement would be any old pulse-rated polypropylene type. But it will be a bit larger at full ratings, and much more expensive (not that you would know/care on a repair basis) -- meanwhile the tube fails in a tiny fraction of the capacitor's lifetime.Tim

author: ejeffrey
author_rank: Super Contributor
timestamp: September 05, 2023, 03:04:35 pm
content: Quote from: SilverSolder on April 12, 2020, 07:44:44 pmThere are so called "corncob" lights that have insane light output from an Edison base although it's not as uniform as a cfl or an led with a good diffuser.

author: Vincenzo
author_rank: Regular Contributor
timestamp: September 05, 2023, 03:29:28 pm
content: Thanks Tim for the info. My other option to avoid buying another cheap $20 22W ballast from a chinese website (found some, for $20, but I'll have to wait weeks without my magnifier) was to put 15 0u1 little tantalum caps in series on a "daughter" boardto replace a 1200v cap.The store I got my replacement bulb from should have had LED replacement (bypassing the ballast board) but the specific HD didn't carry them and I use this tool all day everyday.