Inverter check

[stepgr]

Hi all,

What type of test equipment is needed to check backlight inverters ? With the multimeter there's not much you can check besides the input voltages, would a frequency counter be suitable to check the output ? Anybody with experience on the subject ?

[selldoor]

Re: Inverter check

If you mean testing inverter transformers then we normally advise not to try and test the output voltage as this can be between 1000 and 4000 volts.
This is a link to the suggested method of testing (with the power OFF)

http://lcdparts.net/TransformerDetai...ProductID=2724

There are of course other types of transformer but the idea is basically the same. You measure the secondary wiring resistances (meter on 2000 ohms )and compare - should be within 3%. If you dont know where to measure post good clear pictures of the front and back of the boards they are on and we can help.

[budm]

Re: Inverter check

Using test lamp to verify that you do not have the lamps problem is my first test, then you should have ESR/CAP meter for testing the caps, Ringer tester for testing the transformer, DMM, Hair dryer for heating components and boards, Cool spray for electronics troubleshooting for cooling components, Oscilloscope for looking at the SMPS and Inverter controller IC outputs, good magnifying glass, Isolation transformer andGFI AC outlet for safety, lots of reading on BADCAPS.NET, logical mind and common sense.

Home made test lamp: https://www.badcaps.net/forum/showthread.php?t=19987
Or remove old lamp assemblies from broken LCD panel.

[stepgr]

Re: Inverter check

If you mean testing inverter transformers then we normally advise not to try and test the output voltage as this can be between 1000 and 4000 volts.
This is a link to the suggested method of testing (with the power OFF)

http://lcdparts.net/TransformerDetai...ProductID=2724

There are of course other types of transformer but the idea is basically the same. You measure the secondary wiring resistances (meter on 2000 ohms )and compare - should be within 3%. If you dont know where to measure post good clear pictures of the front and back of the boards they are on and we can help.

Thanks I'll have a look , also if say I have an old panel with ccfl light on it, could I remove the light and use it as a test tube or it would be pointless ?

[budm]

Re: Inverter check

Yes, remove the lamp assemblies and save them for testing the Inverter, it will save a lot of your time to narrown down to find out if you have lamp problems or inverter board problems.

[selldoor]

Re: Inverter check

I didnt risk removing the lamp/s - you can just plug them in to the board you are testing
if the plugs are the same size. It is a bit more cumbersome.