LCD monitor inverter alternatives

So you need a transistor to switch them off when wanted. View in nonproportional font.

| invertor 0v line | | o | | | 3 R1 | C | o--[__]--+__/ | | \ npn tr | R2 > | E | > | | | | | ---------+---+----o 2

The npn tr must be rated for the current the invertor takes. Collector goes to the invertors 0v line. '2' goes to psu connector terminal 2 '3 goes to psu connector terminal 3

R1 and 2 depend on power and beta. Lets say CCFL is 12w max, ie 1A, and beta min is 30, so we need 1A/30 = 33mA base i to power the tr.

Adding dimming is a bit more work, but quite doable.

NT

well on the old inverter like you listed, there is a signal wire. the processor in the LCD controller switches the inverter on and off via that signal wire.

So like he suggested, take an NPN transistor tie the collector of the NPN transistor to the ground of all the inverters. and tie the emitter to ground. so when the transistor is turned off, the inverter circuit path is broken, so they are off.

then take a 1k resistor from the base of the transistor to the signal pin for the old inverter connection, make sure the transistor can handle the current of the inverters.

Then, plug it in, the inverters should be off. turn on the monitor and feed it a signal, the monitor will then send out 5V on the signal pin, which is more than enough to saturate the transistor, turning on the inverters, as the transistor is sinking the current to ground.

Two things:

1. Can you see what chip is on these inverters?
2. What chip is on the original inverter?

You might be able to tap directly into the new inverters from your old controller, if the chips have an enable pin.

if he is using PC CCFL invertsers like i says hes using, most likely its a simple 2 transistor inverter. :)

The old faulty inverter uses the BIT3105 CCFL controller chip FYI, I tried to replace the four shorted mosfets (FDS8958A) but they still keep frying...maybe a shorted primary winding on one (or more) HV transformers?

The cheap "PC-mod" inverters seem to work great so far with the transistor switch.

Thanks for the help everyone!