Invertor problems

[terry]

Can any one please help,

I have 5 stand along 17" tft inverters, all with the same problem. Thay have 4 outputs for 4 light, 2 at the top and 2 at the bottom. When I power them up the 2 top light work fine but the bottom 2 only light up half way (looks as if thay are not getting enough power) I have changed the light around and stil the same, so the problem is the inverters not the lights. I have changed all the caps and still the same. My question is what can made this happen.

Thanks for any help

[PlainBill]

Re: Invertor problems

It's an interesting problem, and frankly I don't have a good idea why it's only happening on the lower pair. As a first step, I would try resoldering all terminals on the transformers. See if that changes anything. Also, look for any sign of arcing.

The next step would be to swap parts from the lower section with parts from the upper section. The most likely candidate would be the transformer, then the drive transistors. Pictures would help if you want more precise directions.

PlainBill

[lkraemer]

Re: Invertor problems

Here is my suggestion on your problem!

If you look closely at the Photo I have included, you will see how the power
is generated for the CCFL's. Now, you have two of these circuits, UPPER &
LOWER supplying 4 CCFL's. Since you can swap CCFL's and you have the
same problem, it is associated with only one PLUG. Can't possibly be a
Transformer (unless you have a separate Transformer for each CCFL) because
one Transformer supplies two bulbs. It could be the small cap (CY2) is open
on the HV AC output side right before the Plug, a cold solder joint, a blown
circuit board trace, or internal to the PLUG. If you swapped the CCFL, and it
worked it can't be the CCFL.

One trick you might want to try is to get a Neon bulb, trim one lead off the
Neon, and wrap the other one around a wood skewer. While holding the wood
skewer, you can move the Neon in proximity to the wiring for the non-working
CCFL, and see if the Neon Bulb lights. That proves you have HV AC going to
the CCFL. And you can test on a good circuit to know exactly how bright
it should be. (While I haven't tried this on a CCFL yet, it should work.)

Let us know what you find.

How many Transformers does your Inverter really have?

lkraemer

[EGuevarae]

Re: Invertor problems

It's an interesting problem, and frankly I don't have a good idea why it's only happening on the lower pair. As a first step, I would try resoldering all terminals on the transformers. See if that changes anything. Also, look for any sign of arcing.

The next step would be to swap parts from the lower section with parts from the upper section. The most likely candidate would be the transformer, then the drive transistors. Pictures would help if you want more precise directions.

PlainBill

Agree with PlainBill : post pictures so you can get better suggestions.

[terry]

Re: Invertor problems

Thank for the help, it was a faulty transformer.

[Bobdee]

Re: Invertor problems

Thank for the help, it was a faulty transformer.

Hello Terry
Can you give us some info, I and some members no doubt would like to know
1.What make and model of monitor did these inverters come out of ???
2.What was fault in transformer (bad solder or burnt out section etc) ???
3.How many transformers on inverter ??? (I presume two)
Thanks
bob