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I have an old table lamp. I want to repair it. It has an external ballast circuit and 9 watt fluorescent lamp (PL). I don't know the circuit is working or not. Is there any way to check it without buying a new lamp ? What inductance and what resistance values would be reasonable to expect from a good ballast?

If circuit is okay then I can go for buying a new lamp, otherwise I want to repair the circuit.

Any help would be appreciated.

Update As per the answer and few comments, I have bought a new lamp. After fixing some soldering and wires it is working now. Thank you all.

Here is the link for the lamp I used: http://www.lighting.philips.com/main/prof/lamps/compact-fluorescent-non-integrated/pl-s/pl-s-2-pin/927901786503_EU/product

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  • \$\begingroup\$ It is difficult because the electrical properties of a gas discharge tube (i.e., fluorescent lamp) are not easily reproducible using any other component. It has an unusual I-V characteristic. Fluorescent lamps work somewhere between points I and K on that plot. \$\endgroup\$ – Oleksandr R. Jan 24 '16 at 16:28
  • \$\begingroup\$ If you intend to repair the circuit in any case, go ahead and buy the lamp. \$\endgroup\$ – Dave Tweed Jan 24 '16 at 16:33
  • \$\begingroup\$ Can you posts a data sheet or a part number for the ballast or the lamp? \$\endgroup\$ – EM Fields Jan 24 '16 at 18:26
  • \$\begingroup\$ It is a custom made ballast circuit. I don't think that I can found part number of the ballast, rather I can post image of the circuit @EMFields \$\endgroup\$ – palash Jan 25 '16 at 7:02
  • \$\begingroup\$ I have updated the question for your reference. \$\endgroup\$ – palash Jan 25 '16 at 17:19
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Different ballasts have different strategies for delivering the initial high voltage, then a reasonably constant current. It will be difficult to test the ballast without knowing its individual specs, and difficult to repair if broken.

It will be easier to test the lamp in some cases. If the lamp has two pins at each end, then connect a ohmmeter between the pins, separately at each end. There should be a heater, like a lightbulb fillament, between the pins. For a small lamp like yours, the resistance will probably be in the 10-100 kΩ range. No matter what, it should be clearly distinguishable from a open circuit. If the ohmmeter reads open circuit, then the heater fillament broke and the lamp is no good.

If the lamp has a single pin at each end, then you can't reasonably test it yourself.

Otherwise, just get a new lamp and see if it works. They aren't that expensive.

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  • \$\begingroup\$ Thanks for your reply, the lamp has single pin at each end. I will definitely buy a lamp and then I will let you know the status. \$\endgroup\$ – palash Jan 24 '16 at 17:02

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