Bench Testing a CFL Bulb

The CFL uses an internal power supply, so you pretty much need to apply power to the bulb.

Maybe you could make or find some form of push in socket that would allow you to quickly insert a bulb.

Obviously, be careful when using high voltage.

Regards.

I suggested to modify himself instead searching for. Good techies can find solutions to their day to day problems.

I prefer your answer for his problem.

Just cut the female end off an extension cord, strip the insulation back on the leads, plug the male end into the power strip you must surly have on the back of the test bench and apply 120V AC to the contacts on the bulb. That way the bulb can rest on the bench, thereby satisfying the "bench test" requirement.

...if not the safety ones...

Power up your Tesla Coil and stand near it. Does that lamp fluoresce? If it does you at least know that part of it works.

I can't vouch for the internal electronics, but if the bulb takes direct strikes it probably won't matter anymore.

I like your style, a great example of thinking out of the box.

JoaT has the correct answer. The switch mode power supply switches in the HF band, (read the label). If you're careful you can open it up. You will see the circuit board and the burned component(s). Most of the items have no markings, if you're lucky you'll find a broken wire. I broke the glass on one and installed its base on one that failed. It was outside and got wet.

Just make an unthreaded socket out of copper pipe. Viola! Testing without screwing! Wrap it in rubber hose and you have a safe jig.

Most fluorescent lamps have coils or filaments as you say. Only a few types do not and I will explain the difference. Part of the reason for the coil is to process the emitter coating during manufacture of the lamp. The emitter chemicals outgass when activated by heating the coil during manufacturing. These gases must be removed or the lamp will be ruined. Furthermore, the emitter must not be exposed to air after activation or it will be re-processed and probably suffer short life as a result.

You can verify that a coil should be present by examining the ends of the bulb. There will be two leadwires on each end of the lamp. These leadwires support the coil and transmit electricity into the very low pressure envelope of gas inside the bulb. Typically each coil will measure from 2 to 4 ohms using a standard DVM on the resistance scale. During operation, a voltage of up to 6 volts may be provided to heat up the emitter, kicking electrons into the envelop of gas. At that point the resistance will increase to as much as 5 times the cold resistance.

Only cold cathode lamps have no coil. They only have one wire on each end of the bulb and are more difficult to outgas.

If the coil is missing, or open circuited, then mechanical damage at the clamp may have been the culprit. Attempting to light a fluorescent lamp with only one coil will result in a rectifier effect, just like the old tube diodes back in the days before semiconductors. If this effect is allowed to continue, the heat from incomming electrons (bombarding the ends of the leadwires without the coil) will vaporize the leadwire thereby redepositing them inside the end of the lamp. From the outside, it looks very bright. On the inside, it is very shiney.

Another way to destroy the coils is for a leak to occur. Glass to metal seals can fail over time if the process was out of control during manufacturing. The way to tell the difference is to determine if the gas envelop will still light up before you look inside. This can be done by placing the lamp near any sufficiently high energy electric field. A Tesla coil or RF field is used during manufacturing for quick check of the integrity of the gas envelope. If you are near high voltage power lines, you can also light up a lamp without plugging it in.

In any case, you probably just want to return it to the retailer with a claim on the warranty. If they won't replace it, shop somewhere else.

NUOJ; now you can buy lamps sealed with no metal inside them for long life, 80 to 100k hours. perry

Hi Perry,

You are correct. They induce lamp current through the glass. The only lamps I have seen like that are 10,000 lumen which is great for a basketball court but not very useful at home.

By the way, I let the spell checker get the best of me on my last comment. The vaporizing of metal lead wires makes the end of the bulb look black from the outside not bright.

Sorry for the typo!

http://www.grainger.com/Grainger/GREENLEE-Gas-Lamp-Tester-3T115?Pid=search

Made just for what you are needing. Try it! Kind of expensive for just one bulb, unless you are in a plant, office bldg., etc.

So where in the spec. of this device does it mention testing CFLs?

Regards.

Are you testing in bulk or for customers on demand.

Very easy as suggested by Mr. Anonymous hero, but I suggest a self-modified bulb holder fitted on wall.

To modify just take out the metallic part and plain its inner extrusions by with a jammer and anvil.

This will make it loose enough to put bulb in loosely.

The rest you know how to make centre and side touch together.

Have a nice time.

If by "bench test" you mean a passive test then the answer is you cannot do it. No different to any other active circuit assemblies.

The only way to tell if a CFL works is to energise it and then decide whether it emits enough light for the intended service.

Thanks to all for your comments and replies! This was a general curiosity question with no real application dilema. I love using my Fluke meter when just putzing around and just got curious about this CFL question. Thanks again to all!