Franc Zabkar wrote:
On Fri, 06 Feb 2009 20:04:54 -0500, Jamie
t put finger to
keyboard and composed:


P.S.
I didn't want to override the on signal with something higher than
that in fear of unneeded additional damaged.


FWIW, this 12V Sampo inverter requires a signal greater than 3V to
switch on:
http://monitor.espec.ws//files/sampo...l0048_79al.pdf

According to the circuit diagram, there is a digital transistor
(DTC144) at the on/off input.

The document shows a test fixture where a CCFL can be simulated with a
100K or 110K load resistor. The test current at max brightness is 6mA,
so that equates to a power dissipation of around 4W. The current at
minimum brightness is 2mA. A 10 ohm resistor is used for current
sensing.

- Franc Zabkar
Thanks for the reply, I have found the problem with the inverter.

The link you provided seems to be a little different in design.

The digital transistor on this unit is a PNP that drives the PNP that
turns on the PWM (dual) vcc.

This unit employs a TI1451L dual PWM modulator. etc.

after experimenting with video signals to get a out of sleep mode
state, I've deducted this since it pulls the On/Off trigger low in the
attempt to fire it up.

The first digital PNP is bad. (opened)for lack of better terms..

Also, both electrolytic caps were almost dead!. I replaced those first
thinking it would solve the issue but didn't, it must of been running
on weak caps before the digital tranny died.

I pulled the second PNP base to common and it fired up fine.

Thanks for the help.


P.S.
I don't do a lot of repairs like I used to how ever, I remember it
was a golden rule to always check the PNP transistors first if the
suspected area had one

http://webpages.charter.net/jamie_5"