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N_Cook N_Cook is offline
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Default Alba LCD19advdw, LCD TV and DVD, 2009

Failed backlighting. Firstly 2 off 8pin SOIC with 4 pins commoned for
heatsinking, to drive backlight Tx, on the mains SMPS LV side.
Markings look like
PRAAN
FOS
8862C
under 30x microscope,
google comes up with nothing, anyone suggest likely mistrancription
alphanumerics?

DVD plays and sound emerges, not tried a torch on LCD as all a lash-up
at the moment.
That Tx powers 2 separate tubes with only 2 3KV caps the other
components, 1 of 3.9pF and other 4.7pF , different size tubes likely?.
Both separate secondaries of that Tx measure 830 ohm each
500V Insulation testing showed 200M for each of those 3KV caps.
Not knowmingly have any puffy 3KV caps around and tried 2 x 27pF 12KV
ones instead. The whole unit went into a protection mode it seems, no
DVD or sound. Replaced the original 3KV caps and back to the previous
situation. Does this suggest the 2 drivers are working, they cold test
DVM-D pin to pin combinations matching across each ?
Unplugging each lamp in turn makes no difference.
Only the second time I've peered into backlight operation , so somewhat
unknown territory, previous time was leaky HV caps.