Samsung LE27T51B inverter problem

[PowerAmpFreak]

Hello!
Samsung LE27T51B, the inverter tries to start, a short noise sound is heard, but no backlight comes on. Please see attached picture.
Is there any usual failures on those? Bad transformers?
There are a bunch of SMD fuses, they're OK.
The inverter does recieve +24V and ON-signal.
Could anyone tell the resistance readings on the transformers.
The transformers have marking "4006A533 008"
Thanks in advance!

[tom66]

Re: Samsung LE27T51B inverter problem

Testing across the bulb connectors directly can sometimes work.

[PowerAmpFreak]

Re: Samsung LE27T51B inverter problem

I get different readings across the bulb connections.
1. 12k
2. 1k8
3. 21k (?)
4. 1k8
5. open circuit (?)
6. 1k8
7. 12k

Obviously there are two strange readings. So perhaps those two transformers are bad.
Will it be worth a try to change transformers or better find a new board?

[tom66]

Re: Samsung LE27T51B inverter problem

Pin diagram, incl primary/secondary windings.
http://www.lcdparts.net/TransformerD...ProductID=2740

[PowerAmpFreak]

Re: Samsung LE27T51B inverter problem

Great! Thanks tom!

[budm]

Re: Samsung LE27T51B inverter problem

Does it have one of these black fuse (F5)?

[PowerAmpFreak]

Re: Samsung LE27T51B inverter problem

Does it have one of these black fuse (F5)?

No, it appears to have only white SMD fuses. But they're all OK.

[PowerAmpFreak]

Re: Samsung LE27T51B inverter problem

Today measured the winding resistances of all the 7 inverter transformers.
One of the them has one winding open circuit.
Is it normal that one failed transformer will shut down the entire inverter?
I assume all transformers with its associated drive electronics has fault detection and will disable all inverter action, correct?

This boils down to the decision of either replace the faulty transformer or replace the entire board.
But I think I'll go for the transformer change.

[tom66]

Re: Samsung LE27T51B inverter problem

Yes, one transformer failed will shut down the inverter. The fault detection works on any bulb open, or any over-currrent of the bulbs.

[retiredcaps]

Re: Samsung LE27T51B inverter problem

But I think I'll go for the transformer change.

I repaired a TV with the same bad 4006A transformer. I bought mine from

http://www.ebay.com/itm/150706796810

$5.50 + free shipping.

[budm]

Re: Samsung LE27T51B inverter problem

They look like typical DARFON transformers. Glad you found the cause of the problem.

[PowerAmpFreak]

Re: Samsung LE27T51B inverter problem

Great guys, I'll go for the transformer change. Thanks!

[eklunge]

Re: Samsung LE27T51B inverter problem

Usually if I found there is " two second to black screeb". I will displace the inverter board directly. Please let me know your outcome when you have replace the transformer.
It seems it should more cheaper to replace the broken than the entire inverter board.

Thanks

[PowerAmpFreak]

Re: Samsung LE27T51B inverter problem

Usually if I found there is " two second to black screeb". I will displace the inverter board directly. Please let me know your outcome when you have replace the transformer.
It seems it should more cheaper to replace the broken than the entire inverter board.

Thanks

Yes, I will replace the transformer in a few days and gladly tell the outcome!

[PowerAmpFreak]

Re: Samsung LE27T51B inverter problem

One inverter transformer replaced and set is back to operation!

[tom66]

Re: Samsung LE27T51B inverter problem

Nice one.

[retiredcaps]

Re: Samsung LE27T51B inverter problem

One inverter transformer replaced and set is back to operation!

Wow, you got an inverter transformer from China in less than 5 days?

[eklunge]

Re: Samsung LE27T51B inverter problem

Good job. Can you tell me where to buy the inverter yransformer. Thanks

[retiredcaps]

Re: Samsung LE27T51B inverter problem

Good job. Can you tell me where to buy the inverter yransformer. Thanks

Seriously?

Did you read Post #10???

[PowerAmpFreak]

Re: Samsung LE27T51B inverter problem

Wow, you got an inverter transformer from China in less than 5 days?

Not from China, but from a local component supplier!