Help identifying part on samsung lcd main board

[crosstalk]

I have been trying to figure out why my samsung ln40b630 won't power on. The power supply voltages seem to be ok (maybe a bit low on the 13v rail). Looking at the main board, I think I found a regulator (assuming it is a regulator) that has 0v output with 9v input. Can anyone identify this part? Is it a 1117 with 2.5v output? The markings if you can't see the photo are a sideways C with 11 on the first line, 17-25 on the second line, and 0917AG on the third line.

[kasfamily]

Re: Help identifying part on samsung lcd main board

Maybe LM1117 -2V5

[Neelix]

Re: Help identifying part on samsung lcd main board

.

[selldoor]

Re: Help identifying part on samsung lcd main board

Yes it is a 2.5v LDO

[Neelix]

Re: Help identifying part on samsung lcd main board

How were you able to tell that it's a 2.5V regulator?

[selldoor]

Re: Help identifying part on samsung lcd main board

I have come across similar ones before on these chips produced by
(BacKwardC)ll both 17-33 and 17-25

Three of us believe it to be 2.5v why would you think it would be something else?

[Neelix]

Re: Help identifying part on samsung lcd main board

I don't recall having come across ICs like that before and was just curious as to how you guys were able to tell it's a 2.5V regulator, so that I could also learn

[kasfamily]

Re: Help identifying part on samsung lcd main board

I personally know him and repeatedly met before

[ERICSSON89]

Re: Help identifying part on samsung lcd main board

117-25 or 17-25? because I only know 117-25 is fixed regulator 2.5v output, but this 17-25 I'm little confused here

[selldoor]

Re: Help identifying part on samsung lcd main board

117-25 or 17-25? because I only know 117-25 is fixed regulator 2.5v output, but this 17-25 I'm little confused here

How can you be confused? - it is perfectly clear in his picture.



@ crosstalk - just replace it with any 1117 2.5v that has the same
dimensions


And here is a 17-33 3.3v from the same stable
https://www.badcaps.net/forum/attach...6&d=1391555176

[ERICSSON89]

Re: Help identifying part on samsung lcd main board

ok I see that now. 1117-25 & 17-25 are same right?
since he is getting the input voltage and no output I think he should replace with the same type

[crosstalk]

Re: Help identifying part on samsung lcd main board

Thank you, everyone, for the help.

[budm]

Re: Help identifying part on samsung lcd main board

Did you also check the resistance on the output pin and ground to make sure you do not have shorted load or very low resistance?

[crosstalk]

Re: Help identifying part on samsung lcd main board

Thanks, budm, for pointing out to check whether the output is shorted to ground. It does not appear to be shorted. It would be amazing if replacing the regulator fixes the board.

[electricboyo]

Re: Help identifying part on samsung lcd main board

I have personally seen a faulty LM1117 LDO chip. Not burned, no physical damage, but still it had no output. There wasn't a short circuit on the output. In my case, replacing the faulty LM1117 permanently fixed the problem.

The LM1117 is such a popular chip that many different companies make them. Perhaps they are not all equal in quality?

[Agent24]

Re: Help identifying part on samsung lcd main board

The LM1117 is such a popular chip that many different companies make them. Perhaps they are not all equal in quality?

Very likely. And/or the design is running them too close to their maximum ratings.