I posted this question a week ago but did not get any responses. I have
three "dead" inverter boards that came from an older IBM Thinkpad 600
series laptop. This tiny card converts low voltage to higher voltage
high frequency AC that is then used to light up the fluorescent
backlight tube(s). The symptom is that it will come on for a short time
(I can see the fluorescent tube glows for a 20-30 seconds, then just
before the laptop hinished its POST, the light goes out. While it is
on, I can hear a slight high frequency chirp from the card, then its
off. So a component in there is bad. Does any of you repair gurus have
any experience working with this kind of circuits and possibly tell me
what is the typical failure mode components that caused this behavior?
TIA. Note: spraying "freeze" on it did not help to bring it back.