How to Repair a Dead Fluorescent Light Fixture With a CFL

by Beretta_al390

68K79

Intro: How to Repair a Dead Fluorescent Light Fixture With a CFL

Hi everyone! I have two light fixtures in my kitchen ceiling, with two round fluorescent tubes each. Several weeks ago, one of the small 22 W tubes died, and I replaced it with a new one I bought at a dollar store. To my surprise, it didn't work, so I thought "well, it serves myself just fine for buying dollar store rubbish, let's buy a good one this time", so I went to a normal shop and bought another one. To my astonishment, it didn't work either. Since it was only the small 22 W tube, and the fixture had a 32 W one, I ignored the problem. Less than a week later the 32 W tube went dead, and so did the 22 W from the other fixture. Since my kitchen was poorly lighted at night, I decided to repair the lamps.

STEP 1: Disclaimer

Electricity is dangerous, don't use the information in this instructable if don't know your way around it. Disconnect your home main switch before doing anything. I take no responsibility for any damage to person or property or death. Use this information at your own risk. Compact fluorescent lamps are dangerous. Their tube may contain mercury and you may get cut with shards of glass. Use gloves and a respirator, and work in a well ventilared area.

STEP 2: First Repair Attempt

I disassembled one of the fixtures and took it to my workshop. I looked at the parts, and it was very simple, just an electronic ballast and some wiring. After checking the wires and connections (by plugging the lamp, disassembling the round fluorescent tube, and checking each one of its interior wires with a test light screwdriver) and seeing they were OK, I deduced the problem would be with the electronic ballast (dahhh!) So I went to an electronic store and asked for three new electronic ballasts for my lamps. The clerk told me they cost around 30 euro each, more than the fixtures, so I gave the ballasts back to him and thought of another way to fix the lamps.

STEP 3: Second Repair Attemp

I disassembled the electronic ballast, and saw several ill-looking capacitors and resistors, so I went to another electronic store and bought new ones and replaced the old ones with them. It didn't work, so I started googling for electronic ballast in order to learn how they work, in order to repair them. After a while, I found out that CFL's have an electronic ballast inside, so my bulb lighted (eureka!!!).

STEP 4: This Is the Good One

First I went for the 32 W tube electronic ballast, so I bought the most similar CFL I found (at the dollar store), wich was a 30 W. I took it to my workshop and disassembled it by sawing it and levering with a screwdriver. Sorry, the photos are of the 22 W one, I didn't take pictures of the repair of the 32 W, since I wasn't very confident it would work. By the way, I found 22 W CFL's at the dollar store.

STEP 5: Get the Electronic Ballast From the CFL

The electronic ballast is connected to the CFL by 6 wires, 4 to the tube and 2 to the base. Cut them all, but leave the base ones as long as possible since we will use them later

STEP 6: Preparing the Electronic Ballast for the New Connections

The four wires that went to the fluorescent tube are rolled around four pins in the PCB. Desolder and withdraw the pins. Strip the endings of the other two wires.

STEP 7: First Connections

We are going to use the connectors from the old electronic ballast. Take the old electronic ballast. In one of its sides you will see four wires. These wires are equivalent to the ones in the ballast from the CFL. Now we have to pay a look at the PCB of the ballasts. We will see that two of the wires are connected between them through a capacitor, in the two PCB's. Desolder these two wires and strip their endings. Since I know nothing about electronics, I have made the connections just as they were in the original ballast. Look for the equivalent places in the CFL ballast PCB. Solder the two wires in them.

STEP 8: Second Connection

Now look for a wire in the old ballast PCB wich is connected to a coil-like component (sorry per my lack of knowledge in electronics). Desolder it, strip the ending and solder it in the equivalent place in the CFL ballast.

STEP 9: Third Connection

Desolder the last wire in the old electronic ballast and solder it in the remaining hole in the CFL electronic ballast.

STEP 10: Test

Join the two wires in the opposite side of the CFL ballast to a plug (I used a screw terminal). Connect a fluorescent tube. Plug the CFL ballast in an extension cord. Put the ballast and tube as far from you as you can (just in case anything goes wrong) and finally plug the extension cord in a wall socket.

STEP 11: Making a Case for Your New Ballast

I used the remains of the CFL and some isolating tape to make a case for my new ballast. Now, reassemble the light fixture and you are ready. Thank for reading. Sorry per my English. Spanish version coming soon.

8 Comments

Beretta_al390 8 years ago

Thank you, friend.
By the way, one of the ballast still works after 2 years!

Hitechcomputergeek. 8 years ago

Well, obviously you did know something about electronics...

Good job for even trying this. If I didn't know a lot about electronics, I'd be too scared to try something like this. Heck, I know a moderate amount of electronics (more of a computer programmer), and I'd still be too scared to try this.

As per the below comments (don't want to reply to it because it's a year old), I'm not really sure how the ballast works exactly, but I've heard (https://www.instructables.com/id/Take-apart-a-Compact-Fluorescent-Bulb/?ALLSTEPS) that it's actually a really simple circuit, and I doubt there would be too much variation between different circuits. I still would think that the CFL one wouldn't be built to last as long, though.

Also. the coil component is a transformer.

MikB 10 years ago

All great stuff, but you do realise though that the ballast in a CFL is intended to be a disposable item, and is therefore cheaper, nastier, and less well engineered than the electronic ballast modules you have replaced -- which are meant to outlive many replacement tubes in their (hopefully) longer lives?

Just saying, you may need to do this again, and again :) You're probably still ahead in $$$$ even if you do!

Beretta_al390 10 years ago

Thanks for you comment Mik, I cannot agree more :) just the same thing I thought! CFL's in the dollar store cost about 1,20 € each; nevertheless, I made this repair in March and it still works (I thought the whole contraption would explode in less than a week :D)

MikB 10 years ago

"Keep it far from you in case anything goes wrong" :)

Well, of all the CFLs around here, most die due to dimming, flicker, then out. I've had two go BANG, as in split the CASE apart and blew the fuse. So when you case it up, allow an exhaust port!

To be honest, even something as small as a 20mm fuse going BANG at close range can spoil your day (PC power supply, replacement open-style inlet fuse failed showering glass up in the air, luckily I was ducked down plugging it in!), so yes, I'd cover the thing over with a cardboard box and plug it in, then peep cautiously under. Especially the first time!

Beretta_al390 10 years ago

Hi
In fact I had some explosions when I replaced the capacitors and probed the ballast with the test screwdriver (I was at hand reach when it happened, I was real scared); next time I was at a safe distance; I have a nice burn mark in the wooden floor of my garden shed as a result of the explosions. Keep it far when trying.
I did leave some vents when making up the case, because I saw the original ballasts had them.