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[email protected] PlainBill47@yahoo.com is offline
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Default Sceptre X9G Komodo monitor - Identifying a transistor

I'm developing a love / hate relationship with SMD devices. I love
them when they work, and even when a parts list is available. When
they don't, and one isn't, they cause a lot of grief.

This particular project is a Sceptre X9g Komodo VII A monitor. This
is a 19" LCD monitor. I'm the second person on the project. The
first earned my admiration by reassembling the monitor after pulling
the power supply / inverter. He even left all the screws in the
appropriate holes!!

After reassembling the monitor for test purposes I discovered it
briefly (about 1 second) dimly flashed something on the screen, then
blanked it. After some exploration, I located a bad solder joint on a
film capacitor in the inverter. Resoldering this didn't fix it, it
seems two transistors are shorted base-emitter. For what it's worth,
this design is similar to the inverter used on Dell E172FPb and
E173FPb monitors. A significant difference, the Dell uses through
hole transistors (2SC5707), the Sceptre uses SMD devices.

The transistors are in a package equivalent to a Sanyo PCP
http://datasheet.digchip.com/413/413...-0-2SD2099.pdf The
transistors have identification that looks somethng like this:

DK
o_
QH

I suspect that these markings identify the manufacturer, the
manufacturer's code for the particular component, and possibly a date
code. Needless to say, none of the SMD identification lists show a
device using either of these codes in a similar package. I started
with Sanyo because they make the transistors used in the Dell monitors
mentioned above. Unfortunately, while Sanyo DOES use the DK code on
their PCP package, the datadheet indicates this is a recent addition
to their product line; this monitor was built in 2005.

Using the 2SC5707 I have been able to make an approximate
determination of the characteristics I am looking for, but searches
are handicapped by the myriad packages used by various manufacturers.

Any suggestions would be much appreciated.

PlainBill