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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Capacitor in series with fluorescent ballast
I had my fluorescent work bench lamp apart today to try to stop an
annoying intermittent buzz from the ballast. It's a typical two 15W tube with separate series inductor ballasts for each tube. I was surprised to see a 4.7uF cap in series with one of the ballasts, but not the other. I'm wondering why they would have put a cap in series with only one ballast? The only thing I can think of is that it might cause one tube to operate 180 deg out of phase from the other to reduce flicker. The cap was shorted and I'm wondering whether or not to bother replacing it. Andy Cuffe |
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"Andy Cuffe" wrote in message ... | I had my fluorescent work bench lamp apart today to try to stop an | annoying intermittent buzz from the ballast. It's a typical two 15W | tube with separate series inductor ballasts for each tube. | | I was surprised to see a 4.7uF cap in series with one of the ballasts, | but not the other. I'm wondering why they would have put a cap in | series with only one ballast? The only thing I can think of is that | it might cause one tube to operate 180 deg out of phase from the other | to reduce flicker. Might also improve the power factor of the whole assembly. They don't usually bother with small lamps however. N |
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"Andy Cuffe" wrote in message ... I had my fluorescent work bench lamp apart today to try to stop an annoying intermittent buzz from the ballast. It's a typical two 15W tube with separate series inductor ballasts for each tube. I was surprised to see a 4.7uF cap in series with one of the ballasts, but not the other. I'm wondering why they would have put a cap in series with only one ballast? The only thing I can think of is that it might cause one tube to operate 180 deg out of phase from the other to reduce flicker. That's exactly what it does, this is a lead-lag configuration, the tubes flicker alternatly to reduce overall flicker. The same basic arrangement is used in preheat F40 twin tube ballasts. |
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