samsung LN-T5271F

[budm]

Re: samsung LN-T5271F

The backligts are on. So there is another board between the T-CON and the main board which can also cause not to have picture on the screen. I need to look more into it how this setup works.

[ilikesteel]

Re: samsung LN-T5271F

Budm,

ok, thanks for continuing to help with this problem. I did find a link to what appears to be a manual for the TV.

http://www.scribd.com/doc/225088145/...Service-Manual

there is a lot of info within the manual, however schematics are not specific to the board numbers. they don't list the board numbers in the schematics.

The board connected to the main board I think it's labled as the FRC board, part number BN41-00918B FHD120FRC_EBGA. my main board is BN41-00904A.

I do see them for sale on the internet.

have we ruled out the main board?

again, much thanks for your time Budm.

ilikesteel

[budm]

Re: samsung LN-T5271F

OK, look at that FRC (Frame Rate Conversion) board and see if there is any fuse on that board. You will need the scope to find out if the main board is sending the signals to the the FRC, and if FRC sends the signals to the T-CON or not.

[ilikesteel]

Re: samsung LN-T5271F

Budm,

ok, checked the FRC board with a magnifier lamp and CANNOT find a FUSE designation on the board. I do have a scope and am willing to go further. tell me what signals to look for and component designation. also, any tips for doing this safely would be appreciated.

ilikesteel

[budm]

Re: samsung LN-T5271F

It looks like you have more than one version of this TV model:
http://www.shopjimmy.com/catalogsear...sung+LN-T5271F

Which boards are in your TV?

[ilikesteel]

Re: samsung LN-T5271F

Budm,

I have:

Power Board = BN44-00184A (IP 351135A)

Main Board = BN94-01432C (BN41-00904A)

T-Conn = No Part Numbers on the board except for what is on the bar code sticker.

Stenciled on the board= 40/46/52HHC6LV3.3

On Bar Code Sticker =S2097, J8F00EO, 000528

FRC board = BN41-00918B FHD120FRC_EBGA

Also has two long inverter boards, one on each side of the TV.

thanks

ilikesteel

[ilikesteel]

Re: samsung LN-T5271F

"bump"

[budm]

Re: samsung LN-T5271F

http://www.shopjimmy.com/media/catal...bn9401442a.jpg

OK, do you see those resistors inside the white outline box between the cap C300 and the IC901, you should see activities on those resistors use the scope. You can also see a bunch of resistors close to the two LVDS connectors that go to the T-CON board, check then for signals also.

[ilikesteel]

Re: samsung LN-T5271F

Budm,

am I looking for a particular waveform or just any type of sine-wave? what voltage level? I will do that tomorrow (saturday) and then post.

thanks,
ilikesteel

[budm]

Re: samsung LN-T5271F

https://cdn.badcaps-static.com/pdfs/...71e64da885.pdf

https://cdn.badcaps-static.com/pdfs/...dc60f5d610.pdf

[ilikesteel]

Re: samsung LN-T5271F

Budm,

ok, will check it tomorrow.

ilikesteel

[RCA2000]

Re: samsung LN-T5271F

There is one thing no one seems to have mentioned yet.

And since you say tis is intermittent--it is a distinct possibility...

Those 4 ribbon cables to the top of the panel--out of the T-con board...they connect to a board--that then leads to the front side of the panel...that is the interface board.

Sometimes--that metal strip on the panel frame--touches that intertface board--GROUNDING OUT--the signal from the panel from the T-con board...

And it is OFTEN intermittent. And the BL will often still light when this happens.

To check on this--take a look at how that top board is mounted..it you see a metal strip near the board--you need to either bend up that strip, so that it is AWAY from that board--or place some insulating material--such as plastic--between the board and that strip. If this is the cause---the picture should then return.

[budm]

Re: samsung LN-T5271F

"I have an intermittent problem. sometimes the set powers on perfectly, and sometimes it will come on with sound and no picture.. I can see from the back of the tv that there is some light visible, but nothing on the screen when it does not display a picture. no obvious connection problems." Darn, I missed that.

[ilikesteel]

Re: samsung LN-T5271F

Budm-RCA2000,

after reading the last two posts can you be more specific on what was just posted. right now, that metallic tape strip was attached to the metal cover over the t-conn board. as you can see from the pics, the metallic tape is not touching anything but the frame right now. also, remember, I cannot even get the menu to appear on the screen.

please let me know what to check for and I'll do it.

right now, if the set powered on properly, I would be getting black and white confetti on the screen, and the menu would appear if I pressed the menu button. I know this is a screwy problem. I almost wished it was a more harder failure which might be easier to find.

when the set does power on properly, it remains on without any problems. it's after turning power off and the set is powered on again, it may come on properly or not. I have seen this happen. most times, it will not come on properly.

based on the information so far have we ruled out the PS board?

only three boards left, main, frc, and the t-conn. all three boards are available on the internet from what I've seen.

budm, should I attempt the scope readings anyway?

what is your opinion from what we have so far where the problem may be?

thanks RCA200 and Budm, can't tell you how much I appreciate the help.

ilikesteel

[ilikesteel]

Re: samsung LN-T5271F

Budm-RCA2000,

I thought I would go ahead and take the scope readings anyway. Powered on the TV and then the scope. my scope wouldn't come up and display the signal line across the tube. looks like a dead scope display. cannot get the readings.

so I then looked at the screen and BANG! the black and white confetti was there as well as a pop up menu indicating no signal present. I hooked up a DVD player and the opening screen of the dvd I put in was there waiting for me to pick a option. I can't believe this, but I couldn't find the remote for the DVD player so I couldn't actually play the DVD! but there it was, a picture on the screen. attached are some pics I took.

????????? Help!

ilikesteel

[budm]

Re: samsung LN-T5271F

If you can probe and look at the signals when it is working so you'll know what the signals look like and when it does not work to see where the signal goes missing. There are some small switching power supplies in the FRC and T-CON also which I still have to see where I should give you the voltage test points to test, but right now we need to find out if we lost the signal from the main board feeding the FRC, or missing the signals from the RFC board feeding the T-CON when it failed to help us narrow down to which board is bad.

[ilikesteel]

Re: samsung LN-T5271F

Budm,

my scope is not working. I cannot get sine wave readings. the most I can do is to get voltage readings with my digital voltmeter. the TV is still powered on and displaying the dvd.

ilikesteel

[ilikesteel]

Re: samsung LN-T5271F

Budm,

OK, I'll do what ever you suggest. how can we isolate the problem without a scope? I can retake power supply voltages at the 24 pin connector again and the voltages on the 5 pin connector on the main board to see if there is a difference from the initial reading when no video/menu was present.

ilikesteel

[ilikesteel]

Re: samsung LN-T5271F

"bump"

[ilikesteel]

Re: samsung LN-T5271F

"bump"