"Don Klipstein" <don@[EMAIL PROTECTED]
> wrote in message
news:slrngc0sav.mpp.don@[EMAIL PROTECTED]
> In <PLKdnQXKYtWlWSLVnZ2dnUVZ_jCdnZ2d@[EMAIL PROTECTED]
>, Dave
wrote:
>
>>It seems to me that a flourescent ballast is probably just a transformer
>>and
>>a high-voltage electrolytic cap. And when it "goes out" it's probably
>>because the cap failed. If these are true, could I just replace the cap
>>and
>>make it work again? Assuming (hate that word) of course that I could
get
>>the ballast open. What thinks the group? Please offer whatever
laughing
>>criticism or encouragement you feel is appropriate. I do not need a
fire
>>hazard in the kitchen...
>
> There are several different kinds of fluorescent ballasts.
>
> 1. Simple choke - has 2 leads, usually used with a starter
(occaisionally
> a "push-to-start" switch). There is normally no capacitor.
>
> When they fail, there is generally no repair other than rewinding
> (extremely unlikely to be worth the time and effort), and sometimes the
> core is welded together.
>
> 2. High leakage reactance autotransformer - has 3 leads, and is
> effexctively a choke combined with a step-up transformer. Same story as
> 1.
>
> A variant is the 1-lamp trigger start ballast, which has filament
> widnings added. It is still essentially non-user-serviceable.
>
> 3. The USA-usual "traditional" dual-4-footer - high leakage
> autotransformer with a capacitor in series with the secondary. Also has
> filament windings and a small capacitor (in the ballast case along with
> all other parts) to leak a small amount of current around one lamp to
help
> start the other when both are not conducting but voltage is applied.
The
> 2 lamps are in series with each other.
>
> If the lamp-series capacitor (which is not electrolytic) shorts, lamp
> current will be somewhat high and ballast input current will be very
high.
>
> There are similar "trigger start" ballasts for 2 2-footers.
>
> The case is usually packed with tar. This one is also essentially
> non-user-serviceable.
>
> 4. Electronic ballasts - more repairable than the others, but only by
> those who know how to troubleshoot and repair them *safely*. Capacitors
> may store charge, and improper repairs may add a fire risk.
> It may be difficult to verify that replacement parts are of
> suitable grades (temperature rating, life expectancy at given
temperature,
> voltage and frequency, also failing less catastrophically, any flame
> retardance/resistance) and with suitable characteristics (such as losses
> sufficiently low to prevent overheating - and capacitors have 2 main
> losses).
> Also, one is unlikely to repair a ballast for less (including value of
> time) than to replace it.
>
> Bottom line: Fluorescent lamp ballasts are generally unrepairable.
>
> - Don Klipstein (don@[EMAIL PROTECTED]
)
Thank you, Don. This backs up the conclusion I had basically come to,
making me feel better about replacing the offending ballast. Much
appreciated.
Dave
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