My understanding is that Fluorescent bulbs require a "starter" of some kind.
Is that it, that's shown in the picture? If not, then what is that part for?
Issue 3 of 2016_08_15
Hy again Mark,
There are a few different types of fluorescent tubes (FTs). The tube in your lamp is likely to be a a Compact Fluorescent Lamp (CFL) that are widely used in room lighting or a Cold Cathode Fluorescent Lamp (CCFL) as used to back illuminate LCD displays on monitors and TVs.
CONSTRUCTION of FTs
(1) FTs comprise a tube filled with gas, typically mercury vapor, and a traces of other gasses to promote easier starting.
(2) Electrodes are fitted to each end of the tube. CFLs have a heater at each end and thus have two terminals at each end but CCFLs have no heaters and thus only have two terminals.
(3) The inside of the glass tube is coated with a fluorescent coating which emits light when the coating is struck by ultra violet light.
OPERATION of FTs
(1) A high AC voltage (50HZ to 50KHz) of between 400V and 2KV peak is connected between the two electrodes. This causes the gas to ionize and generate ultra violet light.
(2) Once ionization has started, and the gas has heated up, ionization continues at a lower voltage, typically 400V peak.
(3) The ionizing gas gives off ultraviolet light, but not white light, which causes the florescent coating on the inside of the tube to emit white light. The florescent coating comprises a mixture of materials formulated to emit white light.
(4) CFLs need their two cathodes to be heated before they will start but, once they have started, the heaters can be turned off as the ionization of the gas provides sufficient heat to continue operation. On the other hand, CCFLs, do not have heaters, and rely on a sufficiently high voltage across their terminals to initiate ionization.
DRIVING FTs
(1) Small FTs, like in your table magnifier lamp, are normally driven by an inverter.
(3) The inverter operates from DC, in your case rectified 110V 60Hz, which would give a 150V DC supply line.
(4) The inverter normally has built-in protection, so that if it is overloaded by a high current it will shut down or blow a fuse.
FAULT FINDING (WARNING: DANGEROUS VOLTAGES ARE PRESENT ON ALL PARTS OF THE FLORESCENT TUBE CIRCUIT. ON NO ACCOUNT TOUCH ANY PARTS OF THE CIRCUIT OR FLORESCENT TUBE WHILE THE UNIT IS PLUGGED INTO THE MAINS SOCKET)
Although your control board is discolored, it is not charred and is likely to be still operative.
(1) The first thing is to check all joints for continuity. You will need to remove the insulation over the 'starter' to do this.
(2) Check all wires for continuity. It is common for the wire near to the connection to the FT to oxidize, due to the FT heat, and go open circuit.
(3) Check all joints on the Printed Circuit Board (PCB) for continuity, especially in the area that is discolored. Solder joints can appear to be OK but are in fact crystallized/oxidized and thus a high resistance. It would be best to reflow the joints on the PCB with new solder, especially in the discolored area.
(4) The next step would be to heat the FT to about 70 Deg C with a hairdryer (make sure you heat all parts of the FT) and see if the FT starts up.
(5) Further fault finding is possible which we will be able to define for you if necessary.
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