VO47L master / slave inverter help

[matt@bdtinc.com]

I have a Visio VO47L FHDTV10A with no backlight. I happen to have a spare, known good, PSU and main board. I have replaced the master inverter as it showed physical damage to the IC, and replaced the caps on the slave as they were bulged and way out of spec. I still have no backlight and before replacing the slave inverter i would like to be able to verify that it is bad. Can anyone explain how they function? they are connected to each other through ribbon cables and a wiring harness. They both have 24V to them but I dont know how the master signals the slave to fire. I just want to make sure I didnt get a bad master before replacing the slave as it costs twice as much. Thank you!

[R_J]

Re: VO47L master / slave inverter help

Pictures of the inverters would help, many times there are small fuses on the inverters, Also take a close look at the slave ic, I have seen where the supply pin to the ic is discolored (black) indicating it drew too much current (shorted ic) also check the fets for shorts.

[budm]

Re: VO47L master / slave inverter help

The Master /Slave inverter setup is setup as a push-pull (drive signal is 180 deg out of phase from each other) to be able to drive long lamps. The master provide the out of phase drive signal to the salve.
If the master inverter is working, and the slave is dead, you will see the lamps light up half way the screen then the protection will kick in, if the master inverter output is bad (but the controller IC is good) and the slave is good then you will see another half of the lamps light up and then the protection will kick in.
So you can disconnect the power supply cable to the slave and then look at the screen real close in the dark room to see if the screen lights up for seconds or not first when you first turn on the TV.

[budm]

Re: VO47L master / slave inverter help

https://www.badcaps.net/forum/showpo...4&postcount=39

Look at page 47, 51 for the concept on how MASTER/SLAVE Inverters function