LG L196WTQ-BF Strange issues.....

[DarrenA]

First off, hello all. I have read here for quite some time and always found this site helpfull.
Now to the Issue.
I am working on a LG monitor. 19" Wide Screen. # L196WTQ-BF
This unit powers on, and I can see the screen LG logo ect... for about 2 maybe 3 seconds. then dark. But the Power LED stays on. I have already replaced every Cap on the power supply, with the proper ones. (Before it wouldn't even power up.)
I have ran this as a test. I disconnected the CC Lights from the inverter, and connected only one at a time to one or the other inverter output. Heres the interesting part. the TOP inverter seems to have no output, but the bottom one lights both lamps fine. BUT!!! this only has one transformer... could half be blown?
And Just How do I test the blue Caps on the secondary side of the inverter? Maybe one of them is open or shorted.......
This is the Inverter Number AIP015 And here is a pic of what one looks like http://www.ccl-la.com/blog/index.php...onitor-repair/ I am using that site just for the pictures to show you all what I have.
Thanks for all your help so far, hope this one can also be repaired.

[Rtech]

Re: LG L196WTQ-BF Strange issues.....

using a Meter on about the 2K(2000)ohms Resistance Range.You will note the Transformer has 8 pins .The 4 central ones are the input, and the 4 outside ones are the output to the lamps.These type of Transformer do fail,and usually the output side.Place the meter probes on the two outside pairs,and compare the resistance readings.If there is a difference of greater than 5% betwenn them,suspect the top one in your case will be way off the lower lamp pair, then you have found the problem

[DarrenA]

Re: LG L196WTQ-BF Strange issues.....

I actually removed it last night and tested it. The outputs read 1019 Ohms and 1116 Ohms. Inputs tested and they matched each other. I noticed something, it appears that the inputs of the transformer get power from the same place, they are connected togather. So that seems to be pointing to the output side. Or am I wrong.

[PlainBill]

Re: LG L196WTQ-BF Strange issues.....

I actually removed it last night and tested it. The outputs read 1019 Ohms and 1116 Ohms. Inputs tested and they matched each other. I noticed something, it appears that the inputs of the transformer get power from the same place, they are connected togather. So that seems to be pointing to the output side. Or am I wrong.

You are right. Also notice that the resistance of one secondary is about 10% lower than the other. It is very likely that the transformer with the lower resistance is bad.

PlainBill

[DarrenA]

Re: LG L196WTQ-BF Strange issues.....

K, so I tested that Transformer again. and now its open on the one secondary..... So does anyone have a good used one I could get?

[Rtech]

Re: LG L196WTQ-BF Strange issues.....

This is one of the problems with modern day electronic equipment,particularly with a lot of production being in China etc,that although it is comparitively easy to find replacement parts for mosfets, transistors etc,when it is a 'special' part,like an output transformer,you have got a problem.

[Rtech]

Re: LG L196WTQ-BF Strange issues.....

The other way to confirm whether it is the transformer,is to take it out, reverse it,put it back, and does the fault change to the other lamp circuit ???.

[PlainBill]

Re: LG L196WTQ-BF Strange issues.....

K, so I tested that Transformer again. and now its open on the one secondary..... So does anyone have a good used one I could get?

Is there a number on the transformer? Prices for these can range from reasonable to ridiculous. At least TRY to find a new one.

PlainBill